Six different solvents were used as extraction medium  to check their phenolics extraction efficacy from flour of two rye cultivars. Rye extracts with different solvents were further analyzed for the estimation of phytochemicals and antioxidant properties. Different tests  were performed to check the antioxidant properties and tannin contents in extracts. A bioactive profile of a rye cultivar indicated the presence of total phenolic compounds (0.08–2.62 mg GAE/g), total antioxidant capacity (0.9–6.8 mg AAE/g) and condensed tannin content (4.24–9.28 mg CE/100 g). HPLC was done to check phenolics in rye extract with the best solvent (water), which indicated the presence of Catechol (91.1–120.4 mg/100 g), resorcinol (52–70.3 mg/100 g), vanillin (1.3–5.5 mg/100 g), ferulic acid (1.4–1.5 mg/100 g), quercetin (4.6–4.67 mg/100 g) and benzoic acid (5.3 mg/100 g) in rye extracts. The presence of DNA damage protection potential in rye extracts indicates its medicinal importance. Rye flour could be utilized in the preparation of antioxidant-rich health-benefiting food products. Secale cereale) belongs to the Poaceae family and its genus is Secale. Rye crops are believed to have originated in southwestern Asia and are widely cultivated in Europe, North America and Asia  (ABTS), etc.) were of either HPLC or analytic grade . Standards (HPLC grade) used during different antioxidant assays were procured from Sigma Aldrich. HPLC grade standards  were procured from HiMedia and Sigma-Aldrich, respectively.Solvents  and chemicals . Defatted samples were dried in a hot air oven  and stored . Thereafter, defatted samples were processed using absolute benzene, ethanol, acetone, methanol, acidified methanol  and water in ratio of 1:10 w/v at 50 °C for 40 min in a water bath . The flour–solvent mixture was filtered  and extracts were stored in sample-storing vials at 4 °C in a refrigerator . Rye flour extracts prepared in different solvents were named water rye extract (WRE), ethanol rye extract (ERE), methanol rye extract (MRE), acetone rye extract (ARE), acidified methanol rye extract (AMRE) and benzene rye extract (BRE), respectively. The entire process is represented in Rye grains from different cultivars were milled to fine flour  and passed through a sieve (60BSS) to obtain a uniform size of flour particles (250 micron). Defattation of different rye flour samples (black and white) was carried out with Hexane  were screened for the presence of various phytochemicals .−1 dry weight basis (dwb).TPC in rye extracts  were analyzed using the FCR  method . FCR (50Water extracts (BR and WR) were screened through qualitative and quantitative HPLC analysis ((Shimadzu 10 AVP HPLC system) for specific bioactive compounds. HPLC grade standards  were used. Four different phases were used: phase-A , phase-B , phase-C  and phase-D . The ratio of optimized gradient phase during the analysis was 30:30:25:15 with a flow rate of 1.2 mL/min and a temperature of 30 °C.Percent (%) inhibition of DPPH reagent by rye extracts  was measured . An aliqPercent (%) inhibition of ABTS reagent by rye extract  was measured . An aliq2SO4 (0.6 M) and sodium hydrogen orthophosphate (28 mM). Rye extracts (100 μL) were allowed to react with the TAC reagent (3 mL). The resulting TAC reagent–extract mixture was warmed (95 °C/90 min). Ascorbic acid (mg/mL) was used as the standard. The TAC value of rye extracts was calculated from the equation generated, and results were expressed as mg AAE/g. Absorbance of the rye extract–reagent mixture and standard solution was recorded (695 nm).The TAC of rye extracts  was determined . The sta3[Fe(CN)6]) solution  followed by incubation in a water bath (50 °C/30 min). The reaction mixture was cooled at room temperature followed by addition of trichloroacetic acid (1% 100 μL) and aqueous ferric chloride solutions . The colored mixture was incubated (15 min), which was diluted with distilled water after incubation to prepare the final volume (10 mL). Absorbance of green colored complex was noted (700 nm). The standard used during the RPA assay was Quercetin. The RPA was calculated from the equation generated and results were expressed as mg QE/g. Absorbance of the extract–reagent mixture and standard solution was recorded (700 nm).The RPA of rye extracts  was determined . Rye ext3·6H2O (20 mM)). The fresh solution was prepared by mixing the TPTZ solution, acetate buffer and FeCl3·6H2O solution at a ratio of 1:10:1, then heating in a water bath at 45 °C before performing the assay. Rye extracts (100 µL) were taken in sample vials to react with the FRAP reagent . Reading of the rye extract–reagent mixture (blue colored ferrous tripyridyltriazine complex) was noted (595 nm).The FRAP of rye extracts  was determined . A stock8H8O3)–HCl method [v/v). The reaction mixture was kept undisturbed at room temperature (15 min). Absorbance of the extract–reagent mixture against a blank was recorded (500 nm). For the preparation of the standard curve, catechin was used as the standard. CTC in rye extracts was expressed as mg CE /100 g.The CTC of rye extracts  was assessed using the Vanillin (Cl method . Rye extv/v) to prepare Fenton’s reagent (ascorbic acid (500 μM), Ferric chloride (800 μM) and Hydrogen peroxide (30 mM)). The mixture used to initiate the reaction mechanism was DNA (2.5 μL), nuclease free double distilled water (2.5 μL), extract (5.0 μL) and Fenton’s reagent (10 μL). Reaction mixture was then incubated in water bath (37 °C/45 min). After incubation, loading buffer  was added to the reaction mixture. The results were noted on Agarose gel electrophoresis (1.0%) stained with ethidium bromide (4 μL). The DNA protection potential of rye extracts were evaluated using the retention percentage of the normalized super-coiled DNA, as given below.WRE (black and white rye) was used during DDPPA, and the assay was performed as per previously reported conditions . DiffereExperiments were performed in triplicate to generate results. Afterwards, mean value and standard deviation were calculated. Tukey’s test was used to test significant differences among experiments. Differences among means were considered statistically significant at a 5% level. The score plot, loading plot and correlation for determining the relationship was generated using Minitab software 18.Rye extracts (BR and WR) were subjected to prelim phytochemical assessment, with the results reported in Phenolic profiles of substrates like fruits/vegetables and cereal grains are gaining more attention among researchers, industries and consumers because of their significance to human health. In the present study, six different extraction mediums  were used to extract out phenolic compounds from rye cultivars (BR and WR). Among the selected rye cultivars, black rye (BR) possessed a higher amount of phenolic compounds in the different extraction mediums than the white rye (WR). Extraction mediums used during the experimental work of the present study played an important role when extracting phenolics. Water proved to be the better solvent for extracting total phenolics (TPC) from rye flour as compared to acidified methanol, methanol, ethanol, acetone and benzene. The highest TPC was observed in water extracts (BR (2.62 mg GAE/g); WR (2.14 mg GAE/g)), followed by acidified methanol extracts (BR (1.68 mg GAE/g); WR (1.55 mg GAE/g)), methanol (BR (1.42 mg GAE/g); WR (1.00 mg GAE/g)) and ethanol (BR (0.33 mg GAE/g); WR (0.27 mg GAE/g)). As compared to water, neither acidified methanol, methanol, ethanol, acetone nor benzene were efficient enough to extract out a significant amount of phenolics from rye flour a. TPC inWater extract (WRE) of BR and WR possessing higher amounts of TPC were analyzed using HPLC to identify and quantify the specific phenolic compounds. Ten different HPLC grade standards  were used for the screening of specific compounds in rye extracts. WRE of black cultivar (BR) showed the presence of resorcinol 70.4 mg/100 g), catechol (120.4 mg/100 g), vanillin (5.5 mg/100 g), ferulic acid (1.52 mg/100 g), quercetin (4.68 mg/100 g) and benzoic acid (5.3 mg/100 g) . HPLC an0 g, cate4·7H2O equivalent/g. The lowest value was observed in white rye flour extracted with benzene , whereas a higher FRAP was observed in black rye flour extracted with water . The FRAP value of an extract represents its capability to reduce Fe3+ to Fe2+. Kulichova et al. [Different extracts of rye  were assessed using TAC, DPPH, RPA, ABTS and FRAP assays. These antioxidant assays are either specific color-forming or decolorizing tests that have been widely adopted for screening antioxidant properties in natural extracts via free radical scavenging ,20,51. Aa et al.  studied a et al.  reportedp < 0.01; TAC, r = 0.990; RPA, r = 0.969 p < 0.01; DPPH, r = 0.968 p < 0.01; ABTS, r = 0.882 p < 0.01)  .Fenton’s reagent is extensively used as a DNA degrading agent ,61 durinComparison of different solvents  indicates water to be an efficient solvent for the liberation of phenolic compounds from selected rye cultivars. Maximum antioxidant properties were also observed in water extracts. The presence of specific phytochemicals in rye flour makes it a health-benefiting substrate that can be used in the preparation of various products for human use. For processing flour, the major solvent used at the domestic as well as the commercial scale is water. Efficacy of water for phenolic extraction from rye flour could prove important from an industrial point of view, as it is easily available and cost effective.


This cross-sectional study investigated the mediating effects of emotional problems including depression, anxiety, attention-deficit/hyperactivity disorder (ADHD), and oppositional defiant disorder (ODD) symptoms on the association between bullying victimization and quality of life (QoL) among adolescents with ADHD in Taiwan. A total of 171 adolescents diagnosed as having ADHD participated in this study. Adolescents completed the School Bullying Experience Questionnaire, the Taiwanese Quality of Life Questionnaire for Adolescents, the Taiwanese version of the Children’s Depression Inventory and the Multidimensional Anxiety Scale for Children. Caregivers completed the Chinese version of the Swanson, Nolan, and Pelham Version IV Scale. Structural equation modeling (SEM) was used to examine the relationships among the variables. The results of SEM revealed that bullying victimization indirectly correlated with QoL through the mediation of emotional problems in adolescents with ADHD, whereas ADHD and ODD symptoms did not mediate the association between bullying victimization and QoL. Bullying victimization should be actively prevented and intervened on to ensure better QoL in adolescents with ADHD. Moreover, emotional problems should be alleviated among adolescents with ADHD with bullying victimization experience to maintain their QoL. Bullying is an aggressive behavior repeated over a time period ,2. BullyAttention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder with a prevalence around 5.9–7.2% ,15. ADHDFew studies have examined the association between bullying victimization and QoL in children and adolescents with ADHD. A previous study in Turkey reported no significant difference in the level of QoL between children with ADHD with and without bullying victimization ; howeverThe mediating effect of emotional problems on the association between bullying victimization and QoL in adolescents with ADHD has not been examined. Regarding the association between bullying victimization and emotional problems, several cross-sectional studies have determined a significant link between bullying victimization and increased emotional problems among adolescents, including depression ,27,28,29Regarding the association between emotional problems and QoL, research has reported that emotional problems may reduce the QoL of individuals with ADHD. A longitudinal study indicated that compared with children with ADHD alone, children with ADHD and internalizing comorbidities had poorer family and peer QoL . AnotherThe mediating effect of ADHD and oppositional defiant disorder (ODD) symptoms on the association between bullying victimization and QoL in adolescents with ADHD has not been examined. Regarding the association between bullying victimization and ADHD and ODD symptoms, cross-sectional  and longRegarding the association between ADHD and ODD symptoms and QoL, studies indicated that the severity of ADHD symptoms was negatively associated with the QoL of children and adolescents with ADHD ,46. ODD This cross-sectional study investigated the mediating effects of emotional problems (including depression and anxiety) and ADHD and ODD symptoms on the association between bullying victimization and QoL, in adolescents with ADHD diagnosed based on the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) . Figure This study was conducted in two child psychiatric outpatient clinics in Taiwan between November 2009 and July 2012. The inclusion criteria were adolescents who were 12 to 18 years old and had the diagnosis of ADHD based on the DSM-IV-TR . The excAdolescents’ self-reported victimization of school bullying in the previous 12 months before this study were assessed by using the eight items of victimization subscale on the Chinese version of the School Bullying Experience Questionnaire (SBEQ) in Traditional Chinese . These eAdolescents’ self-reported QoL in the previous 12 months before this study were assessed by using the Taiwanese Quality of Life Questionnaire for Adolescents (TQOLQA) in Traditional Chinese . The 38-The variables of emotional problems in the present study consisted of depression and anxiety. The 27-item Children’s Depression Inventory-Taiwanese Version (CDI-TW) in Traditional Chinese was used to assess adolescents’ self-reported depressive symptoms including negative mood, anhedonia, ineffectiveness, interpersonal problems, and negative self-esteem, in the previous one month before this study ,59. For Caregivers of adolescents with ADHD were invited to completed the 26-item shortened Chinese version of the Swanson, Nolan, and Pelham Version IV Scale (SNAP-IV) ,63, to ap value of <0.05 was considered statistically significant.The adolescents completed the C-SBEQ, TQOLQA, CDI-TW, and MASC-T. The caregivers completed the SNAP-IV. Pearson’s correlation was used to examine the correlations between bullying victimization, ADHD and ODD symptoms, emotional problems, and QoL. Structural equation modeling (SEM) was used to test the adequacy of the model using Amos version 18.0 software  . The max2 = 1.954, df = 29, p = 0.002) because of the effect of sample size [t = 2.53, p = 0.012), the path from bullying victimization to emotional problems , and the path from emotional problems to QoL  reached the significant level, whereas the path from bullying victimization to QoL , the path from ADHD and ODD symptoms to emotional problems , and the path from ADHD and ODD symptoms to QoL  did not reach the significant level. Our full model had acceptable fit , the path from bullying victimization to emotional problems , and the path from emotional problems to QoL  were statistically significant (After nonsignificant paths were deleted, the path from bullying victimization to ADHD and ODD (nificant . The redThe results of the present study revealed that bullying victimization indirectly correlated with QoL through the mediation of emotional problems in adolescents with ADHD. ADHD and ODD symptoms did not mediate the association between bullying victimization and QoL.Bullying victimization is a distressing experience for adolescents who are at the stage of life characterized by the development of social relationships and self-identity. Moreover, bullying victimization harms not only the physical health but also the mental health of adolescents . Thus, wThe SEM findings of this study revealed that bullying victimization was positively associated with ADHD and ODD symptoms among adolescents with ADHD. Previous studies have demonstrated that when victims were exposed to violence during sensitive developmental periods, their developing brain can be affected and that this may lead to neurobiological changes in response to the activation of physiological stress response systems, hence impairing their behavioral regulation ,70,71,72On the basis of the results of this study, we suggest that prevention, early detection, and active intervention for bullying victimization are crucial to ensure better QoL of adolescents with ADHD. Well-designed bullying prevention programs are available such as the Olweus Bullying Prevention Program for the general child and adolescent population . HoweverSome limitations of this study should be considered when interpreting the results of this study. First, the cross-sectional study design made it impossible to determine the temporal relationships among variables. Second, information regarding bullying victimization was collected on the basis of adolescents’ self-reports. Collecting information from multiple informants such as classmates, teachers, and caregivers is needed to confirm the results of this study. Third, there are cultural factors that influence the concepts of bullying victimization and perpetration in children and adolescents of various cultural backgrounds. The terms used for describing bullying-related phenomena, their meaning, and the behavioral manifestations of bullying vary in different countries . Such diThe present study indicated that bullying victimization reduced QoL through the mediator of emotional problems. In addition, the findings indicated that bullying victimization was associated with increased ADHD and ODD symptoms in adolescents with ADHD. We suggest that bullying victimization should be actively prevented, detected early, and intervened on to ensure better QoL in adolescents with ADHD. Moreover, emotional problems should be alleviated among adolescents with ADHD with bullying victimization experience to maintain their QoL.


This review focuses on the evidence for neurotherapeutics for attention deficit/hyperactivity disorder (ADHD). EEG-neurofeedback has been tested for about 45 years, with the latest meta-analyses of randomised controlled trials (RCT) showing small/medium effects compared to non-active controls only. Three small studies piloted neurofeedback of frontal activations in ADHD using functional magnetic resonance imaging or near-infrared spectroscopy, finding no superior effects over control conditions. Brain stimulation has been applied to ADHD using mostly repetitive transcranial magnetic and direct current stimulation (rTMS/tDCS). rTMS has shown mostly negative findings on improving cognition or symptoms. Meta-analyses of tDCS studies targeting mostly the dorsolateral prefrontal cortex show small effects on cognitive improvements with only two out of three studies showing clinical improvements. Trigeminal nerve stimulation has been shown to improve ADHD symptoms with medium effect in one RCT. Modern neurotherapeutics are attractive due to their relative safety and potential neuroplastic effects. However, they need to be thoroughly tested for clinical and cognitive efficacy across settings and beyond core symptoms and for their potential for individualised treatment. Attention-deficit/hyperactivity disorder (ADHD) is characterised by persisting and impairing symptoms of age-inappropriate inattention and/or hyperactivity/impulsivity (DSM-5)  . It is oADHD patients have deficits in higher-level cognitive functions necessary for mature adult goal-directed behaviours, in so-called “executive functions” (EF), that are mediated by late developing fronto-striato-parietal and fronto-cerebellar networks  ,5,6, as The most successful treatment is with psychostimulant medication which enhances catecholamines in the brain, reaching an effect size of ~0.8, with about 70% of patients with ADHD responding to it   were searched with the following key words: ‘electroencephalography’, ‘EEG’, ‘event-related potentials’, ‘ERP’, ‘theta-beta ratio’, ‘TBR’, ‘functional magnetic resonance imaging’, ‘fMRI’, ‘neurofeedback’, ‘EEG-neurofeedback’, ‘electrophysiology-neurofeedback’, ‘fMRI-neurofeedback’, ‘functional magnetic resonance imaging-neurofeedback’, ‘NIRS-Neurofeedback’, ‘near-infrared spectroscopy-neurofeedback’, ‘non-invasive brain stimulation’, ‘transcranial electric stimulation’, ‘transcranial direct current stimulation’, ‘tDCS’, ‘transcranial magnetic stimulation’, ‘repetitive transcranial magnetic stimulation’, ‘rTMS’, ‘transcranial electric stimulation’, each in combination with ‘attention deficit/hyperactivity disorder’, ‘ADHD’, ‘hyperkinetic disorder’, ‘inattention’, ‘hyperactivity’, ‘impulsivity’ and/or ‘meta-analysis’. In addition, the reference lists of articles and reviews or meta-analyses were also hand-searched. Single case studies were excluded.Electrophysiology findings in ADHD showed that increased slower oscillations such as delta, theta or alpha during resting conditions, but also faster beta frequencies bands, are most relevant to ADHD  . The oscCompared to this controversial research regarding inconsistently altered electrophysiological oscillations, there are somewhat more consistent findings concerning event-related potentials (ERPs). ERPs are defined as a task-locked activity, reflecting cognitive, sensory or motor brain responses. Different ERP components showed deviations in ADHD for stimulus discrimination, resource allocation, inhibition, preparation, error detection, and conflict processing ,39  .Several fMRI meta-analyses have been published on ADHD, the majority including fMRI studies using cool EF tasks. They show cognitive domain-dissociated brain dysfunctions in several fronto-striatal, fronto-parietal and fronto-cerebellar regions in ADHD. A well-replicated finding across our three meta-analyses of whole-brain fMRI studies of cognitive and motor inhibition, the latest and largest including 1001 ADHD patients, is that people with ADHD relative to healthy controls have consistently reduced activation in key regions of cognitive control: in the right inferior prefrontal cortex (IFC)/anterior insula, the supplementary motor area (SMA), anterior cingulate cortex (ACC) and striatal regions ,45,52 , orbitofrontal cortex (OFC) and striato-limbic regions during tasks of “hot” EF such as reward-related decision making or temporal discounting tasks. However, deficit findings have been less consistent  ,51.There is furthermore evidence for reduced inter-regional functional connectivity between these task-relevant regions during cognitive tasks and during the resting state, in particular in the dorsal and ventral attention and cognitive control networks . ,59,60.However, not only task-positive regions have been found to be abnormal in function in ADHD, but also areas of the default mode network (DMN), which comprise ventromedial frontal cortex, posterior cingulate, precuneus and inferior parietal and temporal regions and which is thought to reflect task-irrelevant thoughts and mind wandering   is an operant conditioning procedure that, by trial and error, teaches participants to volitionally self-regulate specific regions or networks through real-time audio or visual feedback of their brain activation, which can be represented on a PC. For children, this can be gamified in an attractive way. Given that ADHD is typified by poor self-control   related to impaired state regulation and sleep; and attenuated task-related slow cortical potentials (SCP) such as the CNV correlated with impaired preparation and activation (standard protocols)  . This issue is of paramount importance and a standardization should be aimed for. To date, the already mentioned standard protocols fulfil these criteria and so far, very recently, a few larger studies were published.The latest comprehensive meta-analysis   wGiven that the main aim of neuromodulation is to self-regulate the trained parameters, improvement of brain modulation should be related to clinical improvement and explain clinical outcome. This relation remains understudied   improves outcomes remains to be tested with appropriate control conditions.Real-time fMRI neurofeedback (fMRI-NF), despite its lower temporal resolution relative to EEG-NF (seconds compared to milliseconds), has superior spatial resolution (millimetre rather than centimetre) and has the advantage that it can target the key cortical and subcortical brain function deficits that have been established in ADHD over the past 25 years of fMRI research  , combined with a mental calculation task, while six ADHD patients completed the same task in the scanner but were presented with visual cues indicating level of task difficulty instead of fMRI-NF   in adolescents with ADHD   and electromyography-NF (n = 9). Only NIRS-NF resulted in significant improvements in clinical ADHD symptoms and in cognitive inhibition and attention functions after 11 hourly sessions over 4 weeks, which was, however, not superior to EEG-NF or electromyography-NF  [Only one pilot study so far tested the related neural haemodynamic modulation method of NIRS Neurofeedback (NIRS-NF) of the left dorsolateral prefrontal cortex in nine ADHD children, compared to EEG-NF  .In conclusion, EEG-NF has been tested in ADHD for about 45 years, and a large number of meta-analyses of randomised controlled trials of EEG-NF show consistent small to medium effect sizes for symptom improvements, but still with controversy regarding “probably” blinded raters ,80  .One of the most interesting findings from the existing NF studies is evidence for longer-term delayed consolidation effects which appear to be more pronounced at follow-up than at post-NF treatment assessment points ,117,119 Non-invasive brain stimulation therapies, most prominently rTMS and tDCS, have only over the past decade been applied to ADHD. These stimulation techniques affect cellular and molecular mechanisms involved in use-dependent local and distant synaptic plasticity, i.e., GABA and glutamate-mediated long-term potentiation, which may lead to longer-term effects   rTMS promotes cortical excitability, while low frequency (1 Hz) rTMS inhibits cortical excitability [rTMS is a non-invasive and relatively safe brain stimulation technique that uses brief, intense pulses of electric current delivered to a coil placed on the subject’s head in order to generate an electric field in the brain via electromagnetic induction. A commonly used figure-8 coil can provide relatively focal stimulation of approximately 5 mmtability   compared to sham (n = 9) showed no effect on self-rated clinical or cognitive measures of sustained attention [The majority (four out of six) of rTMS studies were conducted in adults with ADHD. Two double-blind, sham-controlled crossover studies targeted the right DLPFC. In 13 ADHD adults, one session of 20 Hz-rTMS relative to sham significantly improved overall self-rated ADHD symptoms and inattention but had no effect on hyperactivity, mood or anxiety scores   after three sessions   or decreases  in membrane potentials that modify spontaneous discharge rates and cortical excitability, thus increasing/decreasing cortical function and synaptic strength  cortical regions   see  have beeTwo double-blind, sham-controlled, crossover studies applied single session stimulation over the DLPFC. In 15 adolescents with ADHD, anode-left/cathode-right tDCS over bilateral DLPFC improved WCST completion time, n-back reaction times and Stroop reaction times and commission errors to incongruent trials but had no effect on n-back accuracy or Go/No-Go task performance   and switch-task performance, but did not improve working memory, while parents, with one exception, reported improvements in some of their children’s behaviour   or sham while performing a working memory task with inhibitory elements which was repeated after stimulation as an outcome measure. HD-tDCS is a 4:1 small electrode array with one electrode encircled by four electrodes of the opposite polarity, which delivers a more spatially restricted and therefore focal stimulation that can reduce side effects from stimulating non-target brain regions. The study found that neither a single session of conventional anodal tDCS nor HD-tDCS over right IFC combined with working memory performance compared to sham had any effect on performance in the n-back task; however, ERP data from 10 participants in ADHD showed elevated N200 and P300 after the two tDCS conditions versus sham and a shift towards the values seen in a healthy control group  .One study applied one session of anodal tDCS over the right inferior (and some superior) parietal lobe in 17 ADHD children in a single-blind crossover study. In line with the role of inferior parietal lobe in orienting attention, anodal relative to sham tDCS improved performance in bottom-up orienting attention but deteriorated selective attention as measured in the Stroop interference reaction time and error effects and had no effect on alerting or top-down executive attention as measured in the shifting attention and Go/No-Go tasks  .One recent study tested effects of tDCS on reward-related decision making in ADHD   versus sham (n = 8) improved inattention but not hyperactivity/impulsive symptoms immediately after five daily sessions of stimulation and at a 2-week follow-up, with total ADHD scores also improving at the 2-week follow-up, although group differences disappeared at the 4-week follow-up  [n = 18) or a stop task (n = 19) before and after receiving a single session of anodal tDCS over the left or right DLPFC relative to sham. In the Flanker task, left but not right DLPFC stimulation reduced reaction times on incongruent but not congruent trials compared to sham and right DLPFC stimulation. This was furthermore correlated with increased left and right P300 increase in EEG measures on incongruent trials after left and right DLPFC stimulation compared to sham, respectively and with reduced N200 amplitude after left compared to right DLPFC stimulation. In the stop task, there was no effect in inhibitory measures, but left DLPFC stimulation relative to sham increased Go reaction time, which was correlated with increased P200 amplitude during Go trials  [Only four studies have been conducted in adults with ADHD. In a double-blind parallel study in 60 adults, anodal tDCS over the left DLPFC compared to sham had no effect in two Go/No-Go tasks or a functional cortical network activity based on EEG recordings in a subsample of 50 patients   . Finally., 2020) .In conclusion, only 3 out of 17 tDCS studies tested clinical effects. Two studies found that tDCS of left DLPFC improved clinical inattention symptoms while one study foundthat tRNS compared to tDCS improved ADHD symptoms see .g = 0.12) and in n-back reaction times (g = 0.66) [g = 0.21) and of processing speed (g = 0.14) but not of attention (g = 0.18)  [With respect to cognition, most studies found effects in the performance of some but not other tasks, with little consistency in findings between studies, and most studies did not correct for multiple testing see . Two met = 0.66)     .In conclusion, the findings of the use of tDCS to improve ADHD symptoms and cognition have been mixed, with some positive results on improving cognition, with, however, very small effects sizes observed in meta-analyses see also . HoweverImportantly, for both TMS and tDCS but also tRNS or tACS, systematic testing is needed to identify the optimal stimulation parameters that can elicit reliable clinical or cognitive effects. Parameters that should be tested include optimal stimulation sites, frequency, duration, and superiority of stimulation effects combined with cognitive training. For tDCS, tRNS and tACS, studies should consider if effects depend on age, electrode size and inter-electrode distance, the focality of stimulation and antagonistic effects of cathodal stimulation on the desired effect of the anodal stimulation. Children, for example, have thinner skulls and less corticospinal fluid, which means potentiation of the effects of brain stimulation compared to adults and optimal dosages cannot be easily transferred from adult studies. For example, cathodal tDCS at 1 mA, which has excitability-diminishing effects in adults, has shown to have excitatory effects in children and adolescents when applied over the motor cortex   in children with ADHD compared to tDCS and is described above. No studies have been conducted in ADHD with other stimulation methods such as transcranial alternative current stimulation (tACS).External trigeminal nerve stimulation (eTNS), also known as transcutaneous supraorbital nerve stimulation (tSNS), is another non-invasive intervention with minimal side effects. Small electrical currents are transmitted transcutaneously via a self-adhesive, supraorbital electrode to excite  on the supratrochlear and supraorbital branches of the ophthalmic nerve (V1) located under the skin of the forehead. The supraorbital nerve is a branch of the first trigeminal division. The trigeminal nerve has widespread connections to the brain, in particular the reticular activation system, locus coeruleus, brain stem, thalamic, frontal and cortical areas   as well The second study from the same group was a blinded, sham-controlled pilot study of eTNS in 62 children with ADHD from 8–12 years old. The investigator-rated ADHD-RS total score was significantly reduced in the active relative to the sham group, as well as the inattentive and hyperactive/impulsive sub-scores and the Clinical Global Impression-Improvement scores. There was furthermore a trend-level differential improvement in the active group for anxiety but not for depression  . There wWith the exception of EEG-NF, neurotherapeutics is still in its infancy in the field of ADHD.A large number of meta-analyses of randomised controlled trials of EEG-NF show consistent small to medium effect sizes for symptom improvements, but there is controversy regarding blinded raters ,32 . Only three studies, including a study using tRNS, tested for clinical improvements, with inconsistent findings with respect to improvement of inattention. Larger, sham-controlled studies are needed to further test the efficacy of tDCS on clinical and cognitive functions and potential costs on non-targeted cognitive or behavioural functions.In addition, like for fMRI and NIRS-NF, knowledge is needed on the optimal stimulation protocols for different age and patient subpopulations . It is likely that brain stimulation combined with cognitive training has a larger potential to enhance brain plasticity in ADHD than brain stimulation alone. This will also require the development of good cognitive training tasks that target ADHD-relevant functions to be used in combination with brain stimulation techniques. Given its minimal side effects, tDCS or tRNS are promising tools for the treatment of childhood onset psychiatric disorders since they provide the opportunity to positively influence atypical brain development early and possibly longer-term  , with the TMS devices costing over USD 50,000 as opposed to a few hundred to USD 20,000 for tDCS. rTMS also requires larger office space. Furthermore, many manufacturers of rTMS have a pay-per-use business model, which is very cost-ineffective. The administration of rTMS is also more expensive as it requires substantially more training for a clinician/technician than tDCS. Some TMS devices even require localisation via an MRI scan which can add to the costs. tDCS, on the other hand, is small, portable, user-friendly and can be bought commercially and be used at home without a therapist. Even if both techniques are administered clinically by trained staff, cost-effectiveness analyses for application to pain show that tDCS is more cost-effective than rTMS, with lower costs and higher efficacy for pain  (Zaghi eCapital costs for fMRI-neurofeedback are far more expensive than EEG-NF or NIRS-NF, with hourly MRI scans costing typically between USD800–1000 and a device cost of several millions. Certified EEG-NF equipment costs under USD 10,000. However, so far evidence suggests that fMRI-NF learning can be achieved in relatively fewer sessions than EEG-NF  (Thibaul


COVID-19 lockdowns have changed the social and environmental context. Those with ADHD are more vulnerable to experiencing difficulties than their non-ADHD peers. This paper attempts to provide a brief summary of the literature that has emerged during the COVID-19 pandemic.A literature search was completed using the following databases; Embase, Ovid Medline, APA PsycInfo. A total of 36 papers were identified as relevant to the topic.The pandemic has exacerbated the core symptoms of ADHD and co-occurring difficulties. Services have adapted their assessment and intervention protocols for tele-health working and findings suggest that tele-interventions present a viable alternative. However, much of this research utilises small sample sizes and a restricted number of population groups.More research is required to determine the effectiveness of ADHD care during the pandemic and whether adaptations will be retained post-pandemic. At the time of writing this review many parts of the world are still experiencing some degree of social restrictions and therefore the experiences of lockdown will be referred to in the present tense.2.th March 2021. No restrictions on country of origin or language were enforced. All articles that reported information about young people and/or adults with a diagnosis of ADHD or ADHD symptoms were included. In addition, articles that explored the effect of COVID-19 on parents or caregivers of individuals with ADHD were included. This review was also interested in exploring adaptations to neurodevelopmental or mental health services and educational providers. The following terms were used to identify papers that included ADHD: “ADHD” or “Attention Deficit Hyperactivity Disorder” or “Hyperactivity Disorder” or “ADD” or “Attention Deficit Disorder” or “Hyperkinetic Disorder”. This resulted in 364,658 results. Published papers relating to COVID-19 were identified using the following search terms: “COVID-19” and “coronavirus”. This resulted in 262,069 results. When these search strings were combined, 886 papers were identified. 319 duplicates were removed leaving 567 papers. The titles and abstracts of these 567 papers were screened and a total of 36 papers were included. Papers were excluded if they did not explore the effect of COVID-19 on ADHD symptomology, the functioning of people with ADHD or service and/or other institutional provisions for people with ADHD. See A literature search in Embase, Ovid Medline, APA PsycInfo was completed on 183.3.1.Adults with ADHD are identified to have experienced significant levels of emotional and behavioural difficulties during the pandemic but the degree of deterioration is uncertain Regarding mental health, low mood and isolation have been found to increase for young people with ADHD as a result of COVID-19 restrictions Young people with Obsessive Compulsive Disorder (OCD) and a family history of ADHD are also reported to have experienced an increase of OCD symptoms during lockdown Young people are reported to be experiencing sleep difficulties during lockdown due to symptoms of COVID-19, sedentary behaviours, isolation, limited exposure to sunlight, poor sleep hygiene and increased exposure to “blue light” 3.2.National lockdowns and restrictions on face-to-face contact have had a dramatic impact on the services that are provided by institutions and the mode by which these services are provided. Given the high transmission rates of COVID-19 3.3.Referral rates for ADHD assessments have reduced by as much as 80% in Ireland Tele-assessments have been identified as effective in the diagnosing and management of neurodevelopmental disorders, including ADHD Diagnostic assessments that require liaison with schools has been impaired or delayed by the closure of many schools and the capacity of educators. Whilst screening measures can be facilitated remotely either by post or email it has not been possible to undertake behavioural observations when required or monitor the effect of medication within the school environment 3.4.3.4.1.The National Institute for Health and Care Excellence Due to concerns over the potential increase in health risks for individuals with ADHD if medication is not initiated or they fail to access their existing prescriptions, the European ADHD Guidelines Group (EAGG) recommended that it is appropriate to start ADHD medication remotely, with specific stipulations As a result of lockdown restrictions, additional responsibility has been placed on families to ensure that their dependants attend clinical examinations when required, are compliant with their medication and engage in appropriate home-based monitoring. For some families this may increase financial pressures, such as having to purchase blood pressure machines.3.4.2.Given the restrictions around face-to-face interventions, adapted remote psycho-social interventions present a promising alternative to the traditional models for a range of conditions As a result of the restricted access to face-to-face interventions for young people with ADHD, parents are taking on more of the responsibility for psycho-social interventions. For example, using behavioural parenting strategies and self-help versions of evidenced based interventions 3.4.3.The transition to remote study has posed challenges for learning institutions worldwide 3.4.4.There is emerging evidence that lockdown has not had a negative impact and in some cases, it has actually been helpful for young people with ADHD ADHD has been found to be a risk factor for contracting COVID-19 4.Individuals, families and services have had to respond quickly and adapt to familial, social and educational changes. Individuals with ADHD are more likely to be at risk of contracting COVID-19 and are more likely to experience difficulties due to lockdown with both the core features of ADHD and co-occurring mental health difficulties. These difficulties also appear to be more severe than their non-ADHD counterparts. However, it should be noted that some benefits have been observed for young people with ADHD.Services have made attempts to adapt their assessment and intervention provisions with partial success. As might be expected, referrals for assessments and the completion of assessments have reduced during the pandemic. As a result, it is likely that services will need to be prepared for a spike in ADHD referrals following the end of the pandemic and extended waitlists will need to be addressed in a timely fashion. Adapted tele-interventions are reported to have had some success with accompanying benefits. However, to adhere to best practice, the prescription and monitoring of ADHD medication requires regular physical health checks which will need to be completed via face-to-face clinical assessments. The evidence for the efficacy of parent or adult psycho-social tele-interventions is limited. Currently, there is not an evidence base for the effectiveness of remote psycho-social tele-interventions compared with face-to-face interventions for children with ADHD. Due to the nature of this clinical work, it is likely that this will need to be conducted face-to-face. It is also likely that some interventions are more appropriate for tele-health administration than others and post-pandemic interventions may utilise a combination of tele-health and face-to-face interventions.In addition, many adaptations have been made by educational institutions and young people and their families have experienced a number of difficulties managing remote learning. However, advances in these methods of teaching may provide some future flexibility in learning modalities. Further research is warranted in this area.4.1.To date, the majority of the research has attempted to identify the difficulties for people living and working with ADHD during this pandemic. However, a few papers have identified possible benefits of this situation. Further research should explore the benefit of remote learning and assessments and interventions conducted via tele-health compared with face-to-face interventions to determine whether they present feasible alternatives for some individuals moving forward. Specifically, research should explore the exact adaptations or mechanisms of intervention that result in beneficial outcomes There are a number of groups that ADHD research has neglected during this pandemic. For example, adults, older adults, females, black and ethnic minority groups and the LGBTQ+ community. So less is known about how the pandemic has impacted on these groups and what recommendations could be made to better support them. Certain domains are also lacking from the research base, such as how the pandemic has impacted on employment, sexual health, substance use and criminality for those with ADHD.In addition, thousands of different variants of COVID-19 have been identified throughout the world. Some are reported to have higher transmission, infection and hospital rates 5.The COVID-19 pandemic and worldwide lockdown restrictions have created a number of challenges for all those living and working with ADHD. We are yet to see how service provision will change post-pandemic but it is possible that some adaptations may prove more effective for those with ADHD than previous models of support.


Both genetic and pre- and perinatal factors, including birth weight, have been implicated in the onset of attention deficit hyperactivity disorder (ADHD) traits among children. This study aimed to elucidate to what extent the genetic risk of ADHD moderates the association between birth weight and ADHD traits among Japanese children., we included 796 who completed follow-ups at 8 to 9 years of age. Birth weight was categorized as <2000 g, 2000–2499 g, and ≥2500 g. Polygenic risk score for ADHD was generated using the summary data of a large-scale genome-wide association study. The Rating Scale IV (ADHD-RS) assessed ADHD traits (inattention and hyperactivity/impulsivity) based on parental reports. Following previous studies, sex, birth order of the child, gestational age at birth, mother’s age at delivery, educational attainment, pre-pregnancy body mass index, pre-pregnancy or during pregnancy smoking status, alcohol consumption during pregnancy, father’s age, education, and annual family income were considered as covariates. Multivariable negative binomial regression was applied to evaluate the association between birth weight and ADHD traits, while adjusting for potential covariates. The interaction term between birth weight categories and binary polygenic risk was added to the model.We conducted a longitudinal birth cohort study (Hamamatsu Birth Cohort for Mother and Children Study) to investigate the association of genetic risk for ADHD and low birth weight with ADHD traits among Japanese children. Out of 1258 children.Birth weight of 2000–2499 g was not associated with ADHD traits. Birth weight under 2000 g was significantly associated with both inattention and hyperactivity. When accounting for higher and lower genetic risk for ADHD, only those with higher genetic risk and birth weight < 2000 g were associated with inattention  and hyperactivity Birth weight under 2000 g, together with the genetic risk of ADHD, contributes to higher levels of ADHD traits among Japanese children aged 8 to 9 years. The suggested association between low birth weight and ADHD is confined to children with a genetic susceptibility to ADHD, indicating the relevance of genetic-environmental interactions in the etiology.The online version contains supplementary material available at 10.1186/s12916-021-02093-3. Questions: Does genetic risk moderate the association between birth weight and ADHD traits among Japanese children?Findings: Children with birth weight under 2000 g and higher genetic risk of ADHD showed increased severity of ADHD traits at age 8 to 9 years, compared to those with either normal birth weight or lower genetic risk.Meaning: Japanese children born with birth weight less than 2000 g are more vulnerable to their genetic susceptibility to ADHD. Additional attention is needed to minimize the severity of ADHD traits during childhood.Attention deficit hyperactivity disorder (ADHD) is one of the most prevalent neurodevelopmental disorders , 2, accoAccumulating evidence suggests that low birth weight is an early biomarker for newborn infants’ vulnerability to experiencing altered neurodevelopment and developmental disorders , 15. A rBesides the birth weight implications for ADHD, it is well known that ADHD is heritable (70–80%) , 32. A pThe influence of some individual candidate genes and several prenatal factors on ADHD traits is known to some extent. While previous studies have highlighted the importance of gene-environmental interactions in the etiology of ADHD , 40, then=28) and children with Down syndrome (n=2) from this study. Ultimately, 796 children and their mothers were included in this study.This study used data from the Hamamatsu Birth Cohort for Mother and Child (HBC) Study, which is an ongoing prospective birth cohort study designed to investigate the neurodevelopmental trajectories of children in the general population. The children in the cohort were born in Hamamatsu City, Japan, between November 2007 and March 2011. The details of the HBC study are presented elsewhere . In the Birth weight below 1500 g and 2500 g are recognized as very low birth weight and low birth weight, respectively. However, in this study, we had only three children (out of 796) whose birth weight was below 1500 g. Moreover, a recent multi-national study has highlighted the need for redefining low birth weight with a threshold of birth weight of around 2000 g among Asian children . Thus, wp-value thresholds, we considered the best fit PRS for this study. The ADHD-PRS for the included 659 samples had a bell-shaped distribution with a mean of 0.00124 and median of 0.00123  . The detThe main outcomes were the behavioral traits of ADHD, which comprise inattention and hyperactivity domains. To quantify these domains, we used the ADHD Rating Scale IV (ADHD-RS) based on parental reports to assess the severity of ADHD traits at ages 8 to 9 years. The ADHD-RS comprises 18 items covering the spectrum of the inattention (9 items) and hyperactivity/impulsivity domains (9 items) . ResponsFollowing previous studies , 53, thep<0.001 for all three outcomes related to ADHD-RS total, inattention, and hyperactivity scores). Therefore, negative binomial regression models were employed to investigate the association between the exposure and outcome variables. The choice of negative binomial models was determined by considering overdispersion that was present for both the Poisson and zero-inflated Poisson models. The negative binomial regression model provided rate ratios (RR) along with 95% confidence intervals (CIs), which indicates the number of times that the ADHD score is higher (when RR>1) or lower (RR<1) than the reference group. In the case of continuous exposure, an RR value higher than 1 indicates a higher severity associated with a one-unit increase in the exposure, and vice versa. Model 1 was adjusted for variations in survey time only. Model 2 was additionally adjusted for gender, birth order of the child, maternal age at delivery, education, pre-pregnancy BMI, smoking status, and alcohol intake to control for maternal and infant-related factors. Model 3 was further adjusted to include the father’s age at birth, education, and annual family income to control for paternal factors. We found significant interaction effects between birth weight categories and ADHD-PRS. To facilitate interpretation, we classified the PRS into a binary variable using the median value as the threshold. Therefore, any PRS above the median was defined as “having higher genetic risk than average” and PRS values below the median were considered as “having lower genetic risk than average”. We also considered the interaction of birth weight categories and binary polygenic risk variable in the model to estimate the RR for each combination of birth weight category and binary polygenic risk variable. Clustering was allowed for with the Huber-White sandwich estimator in all the included models, as some children included in this study were born to the same mother. Furthermore, background characteristics of children included in the analysis and those excluded from the analysis were compared. The Little’s test for Missing Completely at random (MCAR) was used to test whether missingness of ADHD trait scores and ADHD-PRS were completely at random [Frequency distribution and univariate statistics were used to describe the characteristics of children and their mothers. The data were not normally distributed as indicated by a Shapiro-Wilk test   compared to those born with normal birth weight or had lower genetic risk  and hyperactivity . These results remain statistically significant after additionally adjusting for potential confounders in model 3. The corresponding RRs were 1.56 (95% CI 1.07–2.27) for inattention traits and 1.87 (95% CI 1.14–3.06) for hyperactivity traits (Table N=796) , together with higher genetic susceptibility for ADHD, are associated with an elevated risk of developing ADHD traits during childhood. To our knowledge, this is the first epidemiological study to evaluate the joint contribution of birth weight and polygenic risk of ADHD on the domains of inattention and hyperactivity/impulsivity.Consistent with previous studies , 56–58, By including an interaction term of polygenic risk and birth weight categories to the multivariable models, the risk-conferring effect of low birth weight under 2000 g was found in children with higher genetic risk of ADHD, but not in children of lower genetic risk. This effect highlights that genetic risk could moderate the association between birth weight and ADHD traits. These results were anticipated, as a previous GWAS conducted among English children aged 7 years found a positive association between PRS and inattentive traits, hyperactive/impulsive traits, and overall ADHD traits . In addiNotably, the risk was confined to those born under 2000 g in our Japanese sample, while previous studies from the USA indicated that the risk was observed among children born under 2500 g . This coThe precise biological mechanisms underlying the association between birth weight and ADHD traits remain uncertain; however, several hypotheses have been proposed by previous studies. It may be attributed to the inadequate supply of oxygen and necessary nutrient transport from the mother’s blood to the fetus, known as prenatal ischemia-hypoxia (PIH), which restricts fetal growth and alters placental development, causing low birth weight . PIH cauThe underlying factors of the interaction of genetic risk for ADHD and low birth weight on ADHD traits remains unclear. Therefore, few hypotheses have been suggested to explain this interaction. The complex blend of numerous common genetic variants, such as dopaminergic, noradrenergic, and serotoninergic genes, and rare genetic variants are likely to be implicated in the pathophysiology of ADHD , 69, 70.Our study had several limitations. First, our study had a relatively small sample size, particularly due to the exclusion of participants without genomic DNA collection. The generalizability of the finding is limited to this population until it can be replicated. However, the participants included in the HBC study comprised a representative sample of the Japanese population. Second, our study lacked diagnostic assessment of ADHD. The ADHD traits were measured based on parental reports on their children using ADHD-RS, which may be subject to social desirability bias. However, the ADHD-RS is a widely used, valid, and reliable scale to assess the severity of ADHD symptoms . Third, Despite these limitations, our study has several strengths. The major strengths of this study include the prospective design (birth cohort), lower attrition rate, and representativeness of the sample, making the results of this study applicable to the general Japanese populations. Moreover, this is the first study to investigate the association between birth weight and ADHD traits in childhood while accounting for the genetic risks of developing ADHD. As neurodevelopmental disorders are genetically complex to understand, the inclusion of a single gene marker in the model may not be useful. Since the PRS elucidates the genetic risk through the prediction of complex genetic phenotypes, we accounted for both common and rare genetic risk variants of each participant through the inclusion of PRS in this study .Taken together, our findings highlight the importance of vigilant monitoring of children born with birth weight < 2000 g, especially for those with genetic susceptibility to ADHD. Our findings have several clinical implications. First, it would help clinicians, based on birth weight information, to decide whether a child is at a greater biological risk of developing ADHD symptoms later on. Subsequently, the genetic risk for ADHD should be assessed for children with reduced birth weight to identify whether their biological risk may be exacerbated by their higher genetic loading for clinical ADHD. Such information would also support clinicians in the early detection of other co-occurring neuropsychiatric diseases, including autism spectrum disorder , anxietyIn conclusion, birth weight < 2000 g is significantly associated with an increase in the severity of inattention, hyperactivity, and combined ADHD traits among Japanese children aged 8 to 9 years. The presence of higher genetic risk for ADHD among children with reduced birth weight further elevates such risk. The introduction of effective interventions aimed at reducing the incidence of low birth weight, especially among children whose parents have known ADHD symptoms and diagnoses, may play a crucial role in reducing the risk of developing ADHD.Additional File 1. Figure S1 - Distribution of polygenic risk score for ADHD in HBC study.Additional File 2. Table S1 - Background characteristics of study participants according to birth weight categories.Additional File 3. Figure S2 - Distribution of ADHD total scores between birth weight categories.Additional File 4. Figure S3 - Distribution of scores on inattention traits and hyperactivity traits between birth weight categories.Additional File 5. Table S2 - Association of birth weight (continuous) and polygenic risk with ADHD scores among Japanese children at age 8-9 years.Additional File 6. Table S3 - Independent and interaction effects of birth weight categories and polygenic risk score for ADHD with ADHD total score among Japanese children at age 8-9 years.Additional File 7. Table S4 - Comparison of background characteristics of children included in the analysis and those excluded from the analysis due missing information on ADHD-RS or PRS.Additional File 8. Table S5 - Little’s test for Missing Completely at random and test for covariate-dependent missingness.Additional File 9. Table S6 - Association of birth weight categories and genetic risk with ADHD total score among Japanese children at age 8-9 years after multiple imputation of missing polygenic risk score for 137 children.Additional File 10. Table S7 - Association of birth weight categories and genetic risk with inattention and hyperactivity scores among Japanese children at age 8-9 years after multiple imputation of missing polygenic risk score for 137 children.Additional File 11. Table S8 - Sensitivity analysis for the association of birth weight categories and genetic risk with ADHD total score among Japanese children at age 8-9 years after recoding missing PRS to the end of the spectrum.Additional File 12. Table S9 - Sensitivity analysis for the association of birth weight categories and genetic risk with inattention and hyperactivity scores among Japanese children at age 8-9 years after recoding missing PRS to the end of the spectrum.


Attention-deficit/hyperactivity disorder (ADHD) is a significant neurodevelopment disorder among children and adolescents, with 5 % prevalence. Bone fractures account for 25 % of accidents and injuries among all children and adolescents. Considering the characteristics of inattention, hyperactivity, and impulsivity in children with ADHD, it is critical to examine bone fractures among these children. The objective of our meta-analysis was to determine the prevalence of bone fractures among children and adolescents with ADHD.We completed a systematic review and meta-analysis using an electronic search of the following databases: CINAHL, EMBASE, PsycINFO, PubMed, and Scopus. The search terms used were: “attention deficit hyperactivity disorder OR attention deficit disorder” and “bone fracture*.” We included studies examining patients 18 years or younger who were diagnosed with ADHD and tracked (prospectively or retrospectively) for five or more years. Effect size (es), using a random effects model, was calculated. We registered the review protocol with PROSPERO (CRD42019119527).From 445 records retrieved, 31 full text articles were reviewed and 5 articles met inclusion criteria for meta-analysis. The summary es revealed the prevalence of bone fractures among children and adolescents with ADHD to be 4.83 % (95 % CI: 3.07–6.58 %). The location of bone fractures, using a subset of data, showed a distribution of 69.62 %, 22.85 %, and 7.53 % in the upper limbs, lower limbs, and other anatomical regions, respectively. Another subset of studies revealed a 2.55-fold increase in the prevalence of fractures among the children with ADHD compared to their counterparts.Awareness of these findings is critical to physicians, parents, and policy makers to create safe environments and provide supports in order to optimize the health and safety of children and adolescents with ADHD. Attention-deficit/hyperactivity disorder (ADHD) can be described as a neurodevelopment disorder of impairing inattention, motor hyperactivity, and impulsivity with an onset in childhood and difficulties continuing into adulthood . There hBone fractures account for nearly 25 % of all accidents and injuries among children, with fractures of the distal radius being the most common . The thrOne may assume that symptoms of ADHD, such as hyperactivity, ought to predispose children and adolescents diagnosed with ADHD to a greater number of accidental injuries . This noConsidering the increased risk of injuries among children with ADHD and the high prevalence of bone fractures among children, it is essential to examine bone fractures in children and adolescents with ADHD. To the authors’ knowledge, no review of these findings has been conducted. The purpose of this review is to systematically assess the available studies and to synthesize their findings as a meta-analysis.The authors have adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines in completing this systematic review and meta-analysis . The revThe Cochrane Library and PROSPERO were searched to ensure that the systematic review of fractures among children and adolescents with ADHD had not previously been completed. Then, an electronic search of the following databases was conducted to retrieve studies: CINAHL, EMBASE, PsycINFO, PubMed, and Scopus. The following search terms were used: “attention deficit hyperactivity disorder OR attention deficit disorder” and “bone fracture*.” There were no restrictions set on language or publication dates of retrieved articles. To supplement the electronic search, reference lists from key articles and other systematic reviews on the topic of ADHD and injuries were identified and assessed for articles meeting the systematic review criteria.In order to fulfill inclusion requirements, studies had to meet five general criteria. First, the age range for the population under study was set at 18 years old and younger. If a study’s population age range had 60 % or greater overlap with this age range, it would be included. For example, a study whose population was ages six to 17 years would qualify but a study whose population was 40 years or younger would be excluded.The second criterion for inclusion was a diagnosis of ADHD, which must have been made using recognized diagnostic criteria, such as the DSM or ICD classifications, or the use of prescription medication for the treatment of ADHD in the population. For example, a study that identified participants by relying on a survey to classify children as hyperactive without standard diagnosis of ADHD would be excluded. On the other hand, a study that used the prescription of methylphenidate to indicate the presence of ADHD would be included. This latter decision was made because medications used to treat ADHD are not typically used off-label in children or adolescents for other purposes; therefore, an underlying diagnosis of ADHD is likely present if children or adolescents are being prescribed methylphenidate .The third inclusion criterion concerned the type of study and study methodology. To be included in the meta-analysis, the study must have provided a sample of patients with ADHD followed (prospectively or retrospectively) over a period of five or more years with a subset that have experienced bone fractures. The patients with ADHD could not be part of a specific population, such as Medicaid patients or have fractures sustained exclusively as a result of physical abuse. However, the population was not restricted to any geographic location or setting .The fourth inclusion criterion was the article type. To be considered in the review, articles had to be published in peer-reviewed journals as full-text manuscripts. Conference abstracts and commentaries were excluded from the review. Finally, the fifth inclusion criterion was that the study population was a unique population that had not been covered by any other article in the review. Studies that examined the same dataset or group of patients through various articles were only included once in the meta-analysis. Additionally, it should be noted, that this review was on bone fractures in human subjects only; therefore, studies conducted exclusively on animal models or human dental fractures were excluded.The resulting articles from the electronic search were entered into Mendeley (version 1.19.2) where duplicates were removed. Then articles were assessed based on their abstracts to exclude entries that did not meet the inclusion criteria. Subsequently, full-text articles were retrieved for the remaining entries and examined by two independent reviewers (H.S. and S.M.) to evaluate inclusion into the systematic review and meta-analysis.A data extraction form was created to extract key elements of the study, including findings that could be used to calculate fracture prevalence among subjects with ADHD. Data extraction included the following: (1) author, (2) year, (3) country, (4) study setting, (5) study design, (6) duration, (7) sample size of ADHD group, (8) sample size of control group, if applicable, (9) age range, (10) ADHD diagnosis method, (11) fracture identification method, and (12) fracture locations, if specified.Two independent reviewers (H.S. and S.M) conducted quality assessment of the studies that were included in the meta-analysis using the Joanna Briggs Institute (JBI) critical appraisal tool for prevalence studies . The cheMeta-analysis was completed using a Microsoft Excel tool developed by Neyeloff, Fuchs, and Moreira . The samThe authors decided to use a random effects model to calculate the es of the meta-analysis for several reasons. A random effects model allows for the assumption that factors other than error or chance exist within and between studies. It also allows for the assumption that the studies used are a random sample of a hypothetical population of studies. Additionally, a random effects approach allows for generalizations to be made beyond the studies included in the meta-analysis . JBI enc2 measure. Higgins, Thompson, Deeks, and Altman  included in the meta-analysis was assessed using the Id Altman  recommeno chance . Heterog, p. 1158o chance .The initial database search resulted in 445 articles Fig. . Of thesAs mentioned above, 184 articles were excluded after an examination of their abstracts. Common reasons for exclusion at this point were articles that exclusively examined dental fractures in the ADHD population, the effects of brain injury on the development of ADHD, non-human models, the effects of ADHD medication on fractures, and fractures as a result of abuse. It was also possible to exclude, based on abstracts, several studies that did not meet the age inclusion requirements.n = 4), ADHD diagnosis (n = 8), study type (n = 10), article type (n = 3), and being a population examined by another study that was already included (n = 3). Two of these articles were excluded for two reasons each . Of these, 26 articles were excluded based on not meeting the inclusion criteria of age (Two authors (H.S. and S.M.) assessed the quality of the five included studies and disagreements were discussed until consensus was reached. The characteristics of the included studies are given in Table 2 score revealed a heterogeneity level of 66.63 %, a level that may be referred to as moderate-to-high [The summary es of the meta-analysis revealed a fracture prevalence of 4.83 %, with a 95 % CI between 3.07 and 6.58 . A subset of the studies included in the meta-analysis also determined a 2.55-fold increase in the prevalence of fractures among this group when compared to a control group. Another subset of studies discovered the distribution of fractures among the population with ADHD to be in the upper limb (69.62 %), lower limb (22.85 %), and other anatomic regions (7.53 %).There is an array of possible reasons for injuries and fractures in children with ADHD that may be attributed to the characteristic symptoms of the disorder. For example, parents report that impulsive children do not think before they act, can show poor judgment, and seek immediate gratification . AnotherThe authors have identified several limitations to this meta-analysis including its heterogeneity and the causes of this heterogeneity. Heterogeneity may be clinical, methodological, or statistical. Clinical heterogeneity may stem from differences in the characteristics of the populations in the study . As was Another source of clinical heterogeneity stems from whether medications were used to treat ADHD. In those studies where children and adolescents were identified through their diagnosis of ADHD and not the prescription of medications, it was not known if those experiencing fractures were using pharmacologic interventions for ADHD. It has been reported that the use of both stimulant and non-stimulant medications to treat ADHD is associated with a decrease in the number of bone fractures among patients with ADHD . AnotherMethodological heterogeneity can arise from variations in study qualities or differences in study designs . All of Another shortcoming of the meta-analysis is having only aggregate numbers of fractures among patients with ADHD. It is not known if a patient experienced multiple fractures in one injury event, if a patient had a series of fractures over time, or if each patient had one fracture each to compose the overall fracture numbers. It was also not possible to stratify the prevalence findings by age subgroups or by gender.If studies become available, future meta-analyses should be completed on prospective study designs that can follow children and adolescents with ADHD over time to determine who experiences what types of fractures, from what sources of injury, and at what age. The participants’ usage of medication for the treatment of ADHD should also be tracked.A thorough subgroup analysis is required in future research, especially by age and gender. The modes of injury and bone integrity for a young child may be very different than that of an adolescent. The ability to stratify bone fractures by age can inform measures aimed at preventing injuries that are most effectively aimed at specific age groups. Some studies that have assessed fractures by gender in children and adolescents with ADHD have determined a higher rate among girls than boys when compared to control groups of girls and boys without ADHD . With thBone fractures in children and adolescents are an important concern for public health because they have considerable influence on the activities and daily living of affected children . With an


Tc1/mariner and pogo superfamily, as the most widely distributed transposons in nature, are widely reported in insects. However, in bees, the research on transposons has never been systematically reported. Therefore, this study focuses on annotating the transposons of the Tc1/mariner and pogo superfamily of bees that were sequenced, revealing the distribution, diversity, potential activities, evolutionary patterns, and structural characteristics of transposons in different bees.In the class of insects, bees are advanced evolutionary groups that play a pivotal role in ecosystem balance, agriculture, and food security. Transposons are the driving factors of genome evolution and speciation, which shape the genomes of almost all organisms. Among them, the pogo and Tc1/mariner transposons in the genome of each species, and performed a phylogenetic analysis and determined their overall distribution. The pogo and Tc1/mariner families showed high diversity and low abundance in the 37 species, and their proportion was significantly higher in solitary bees than in social bees. DD34D/mariner was found to be distributed in almost all species and was found in Apis mellifera, Apis mellifera carnica, Apis mellifera caucasia, and Apis mellifera mellifera, and Euglossa dilemma may still be active. Using horizontal transfer analysis, we found that DD29-30D/Tigger may have experienced horizontal transfer (HT) events. The current study displayed the evolution profiles  of the pogo and Tc1/mariner transposons across 37 species of Apoidea. Our data revealed their contributions to the genomic variations across these species and facilitated in understanding of the genome evolution of this lineage.Bees (Apoidea), the largest and most crucial radiation of pollinators, play a vital role in the ecosystem balance. Transposons are widely distributed in nature and are important drivers of species diversity. However, transposons are rarely reported in important pollinators such as bees. Here, we surveyed 37 bee genomesin Apoidea, annotated the  Bees (Hymenoptera: Apoidea), which originated in the early to mid-cretaceous era , are theAntarctic midge [migratory locust [Transposons, also called jumping genes, were once considered junk sequences but were later confirmed to play an important role in genome evolution and size ,12,13,14ic midge  to as muy locust . Transpoy locust ,18,19.Tc1/mariner, pogo, hAT, PiggyBac, CACTA, Helitron, and PIF-Harbinger. The Tc1/mariner superfamily is a member of the cut-and-paste group that was first discovered in Drosophila mauritiana (transposon mariner) and Caenorhabditis elegans . Generally, Tc1/mariner transposon usually has a single open reading frame (ORF) of about 340 amino acids (aa), flanked by two terminal inverted repeats (TIRs) and dinucleotide target site duplications (TSDs) of TA, and it may represent the most widely distributed transposon superfamily in nature [Tc1/mariner families, and have been suggested as major reservoir hosts for DNA transposons and RNA viruses [Transposons are usually divided into two types according to the structural organization and mechanism: Class I represents RNA transposons and Class II DNA transposons. DNA transposons have been widely reported and can be divided into three main types: cut-and-paste, peel-and-paste, and self-synthesizing transposons. Widely reported DNA transposons include: n nature ,21,22. T viruses ,31,32,33Tc1/mariner is classified into DD34E/Tc1 [mariner [TR [IC [maT [TRT [GT [VS [pogo transposon was first found in flies [pogo-like elements were detected, such as Tigger [Fot, Tan1, Pot1, Pot2, Flipper, and Aft1-transposons were found in the genome of fungi [Lemi1 was found in the genome of plants [pogo-like elements were found in the teleost genome [pogo and Tc1/mariner are two distinct superfamilies [Based on the phylogeny of the DDE-conserved catalytic motif, D34E/Tc1 ,36,37,38[mariner ,40,41,42iner [TR , DD36E/I [TR [IC , DD37D/m[IC [maT ,45, DD37maT [TRT , DD39D/G[TRT [GT , and DD4 [GT [VS . The pogin flies , then mos Tigger  was founof fungi ,52,53,54f plants ; and pogt genome . A previfamilies , but repmariner element has been reported in studies of the annotation of honeybees and bumblebees [pogo and Tc1/mariner transposons in the genome of each species; and determined their phylogenetic positions, classification, overall distribution, and structural characteristics. We also investigated the evolutionary patterns of DD29-36D/Tigger and DD34D/mariner transposons. Our data reveal the evolutionary landscape of pogo and Tc1/mariner transposons in Apoidea and will add to the understanding of their contributions to the evolution of the Apoidea genomes.The mblebees ,59. Howepogo and Tc1/mariner DNA transposons in 37 sequenced genomes of Apoidea (taxid:34735), we selected several representative transposase sequences from the well-defined families of pogo  and Tc1/mariner  superfamilies and subjected them to a TblastN search against the Apoidea genomes deposited in a whole-genome shotgun database  with default parameters (1e-10). The information of all genomes in this study is listed in To survey the distribution and diversity of pogo and Tc1/mariner transposases separately using MAFFT (v.7.310). The phylogenetic trees were inferred based on the conserved DDE domain using the maximum-likelihood method in the IQ-TREE program. According to the Bayesian information criterion, the best-suited aa substitution model for these data was the LG + G4 model, which was selected by ModelFinder. The reliability of the maximum-likelihood trees was estimated using the ultrafast bootstrap approach with 1000 replicates [www.timetree.org, accessed on 12 September 2021).For phylogenetic analysis, the conserved DDE domains of the identified transposases were aligned to the representative families of the plicates ,43. Infohttp://bioinf.cs.ucl.ac.uk/psipred, accessed on 1 March 2021). Putative nuclear localization signal (NLS) motifs were predicted using PSORT . The protein domains were identified using the profile hidden Markov models on the hmmscan online web server .Protein secondary structure predictions were performed using the PSIPRED program (EF1-a), heat shock cognate 70 (Hsc70-4), tubulin beta-3 (tub3), and 29 Ribosomal proteins, were used for the comparison with transposon distance to test the HT hypothesis. The three genes  were used as internal controls by other studies including HT analysis of transposons [EF1-a, Hsc70-4, tub3, and 29 universally conserved genes in the US National Center for Biotechnology Information (NCBI) database were not included in these calculations. Multiple alignments of EF1-a, Hsc70-4, tub3, 29 universally conserved genes, and all transposons in Apoidea were created using MAFFT, and the pairwise distances were then calculated using MEGA software  based on two aligned files. The species divergence times were estimated using the online Timetree program . The bar chart was created by Graphpad 8, and then statistical differences were analyzed using a one-factor ANOVA test in SPSS (25.0). Significant differences were assessed at p < 0.05. The genomic copies of DD34D/mariner were annotated by using RepeatMasker  with representative genome of each species, and then calculated the Kimura divergence parameter distance by using the calcDivergenceFromAlign.pl package from RepeatMasker. The Kimura two-parameter distance reflects the transpositional activity of DD34D/mariner on a relative time scale per genome [The pairwise genetic distance between transpsons and the conserved host genes was applied to determine whether these species have experienced HT events. The coding sequences of 32 host genes, including elongation factor1 alpha , we executed a Tblastn search using the NCBI whole-genome shotgun database  using 15 representative transposase sequences from different families of the pogo  and Tc1/mariner  superfamilies. We identified 164 unique elements in 37 species of Apoidea  were classified as members of the pogo superfamily and seven families  classified as members of the Tc1/mariner superfamily were identified in 37 species of Apoidea  of Apoidea, in which most species contained seven to eight transposon families. Most species of Apidae contained only two to four transposon families, particularly in the Apis genus, and most species exhibited only DD34D/mariner and DD41D/VS families. The exception was Habropoda laboriosa, which had one pogo family (Tigger), but variations of DDE domains  and six Tc1/mariner families . This species exhibited the highest diversity of pogo and Tc1/mariner transposons in Apoidea. Four transposon families  were detected in all bumblebees (five species), Melipona quadrifasciata and Frieseomelittavaria, whereas the five species of stingless bee  exhibited only the DD29-36D/Tigger and DD34D/mariner transposon families. The DD29-36D/Tigger, DD34D/mariner, DD34E/Tc1, and DD36E/IC families were detected in Eufriesea mexicana, and DD29-36D/Tigger, DD34D/mariner, DD34E/Tc1, and DD41D/VS families in Euglossa dilemma. Moreover, families of DD29-36D/Tigger, DD34D/mariner, and DD34E/Tc1 were found in Ceratina australensis and Ceratina calcarata, and Ceratina calcarata also includes a DD41D/VS family  and Dufourea novaeangliae , which represented the highest diversity across Apoidea species   , which soneybees .Dufourea novaeangliae, Nomia melanderi, Lasioglossum albipes, and Megalopta genalis belong to the Halictidae family, but they had obvious irregular distribution of transposons, indicating putative HT events of these transposons across species within this lineage. By contrast, two very close species, Ceratina calcarata and Ceratina australensis, also had different distribution of transposons. Moreover, some relatively distantly related species on the phylogenetic tree were closer than closely-related species, for example, the DD29-30D/Tigger family in Dufourea novaeangliae and Megalopta genalis, which belong to Halictidae, but Dufourea novaeangliae was closer to the Osmia lignaria in the Megachilidae family on the clade than to Megalopta genalis, which is a more closely-related species of Nomia melanderi. Considering these findings, we speculate that some transposons might have been exposed to several episodes of HT.HT is an important form of asexual transmission in nature, and there is increasing evidence that transposons are important participants in HT. Generally, HT events will follow three conditions: (1) high sequence similarity of TEs from divergent taxa; (2) incongruence between TE and host phylogeny; (3) a patchy TE distribution within a group of taxa . In our pogo and Tc1/mariner in the bee genome, clusters that are inconsistent with the host phylogeny and have an identity of each cluster of the phylogenetic tree close to or greater than 80%, which may experience HT events, are selected. We detected the presence of HT signs in the four clusters . Then, the pairwise genetic distances between the four host-conserved genes  and these transposons were calculated and compared. we found that the average distance is smaller for DD29-30D/Tigger, DD33D/Tigger, DD34D/mariner-cluster 1, and DD34D/mariner-cluster 2 than for the four host genes  for DD29-30D/Tigger than for almost all host genes, except for EF1-a, RPL2, RPL18, RPL23, RPS8, and RPS9  across these species  domain at the N-terminus and a catalytic domain at the C-terminus. The N-terminal of Fot-like transposase comprises HTH and DNA-binding domain regions, and the C-terminal is a catalytic domain. The Tc1/mariner transposase contains an HTH domain at the N-terminus and a catalytic domain at the C-terminus. The DD29-36D/Tigger transposons invaded almost all species except the Apis genus, among which 26 species contain 58 transposons, representing a high diversity of transposons. The length of all transposons ranged from 907 bp to 4213 bp, and the length of the TIR was 10–33 bp. The overall copy number content was very low, but most transposons included an intact copy. Generally speaking, the last aa of the DD/D catalytic domain of the pogo transposon was ‘D’, but we found an exception in this study. DD33D and DD33E are similar in structure and have a very close phylogenetic relationship. Considering their phylogenetic location and all species that appear in stingless bees, DD33E may have been caused by the DD33D mutation at some stage. DD34D/mariner was found to be the most widely distributed transposon in this study. Almost all bees except Lepidotrigona ventralis hoosana have the DD34D/mariner transposon and it appears to represent a very young transposon family in Apoidea. We found that all DD34D/mariner transposons were around 1200 bp in length and that 24 transposons contained complete transposase. However, among the six Apis genomes studied , we could identify only complete ORFs but could not determine the boundary. DD34E/Tc1 is considered to be the origin of many Tc1/mariner transposons and was found to be a very widely distributed transposon in this analysis. All DD34E/Tc1 transposons were 952–1805 bp in length, and the TIRs were 24–221 bp in length. We also found six Fot-like transposons, namely DD35-36D/Fot in Colletes gigas, Lasioglossum albipes, Megachile rotundata, Osmia bicornis bicornis, Osmia lignaria, and Dufourea novaeangliae. Six transposons were found in DD36E/IC, but they all lost the function of encoding complete transposase. The first five base changes seem to be typical characteristics of some subfamilies. All DD37D/maT started with CAGGG, and DD38E/IT started with CACTA and CACTG. Lepidotrigona ventralis hoosana had an incomplete DD39D/GT transposase with a total length of 2381 bp, which retains the typical characteristics of DD39D/GT transposon beginning with CTCCC. In addition, the recently well-defined DD41D/VS family was also found in this study. Eleven of the 24 transposons had complete ORFs and were 1024–2258 bp in length. All of the bumblebee catalytic domains changed from DD41D to DD40D.Previous studies have shown that the Apis dorsata from other honeybees [Apis mellifera intermissa contains 5.16% TEs with low diversity, most of which comprise simple repeat sequences [Apis mellifera genome, the percentage of TEs is close to 8% [mariner transposons are the most common element within this class [Apis cerana accounted for 9.15% and simple repeats accounted for most TEs [Apis cerana genome and 0.57% (1.34 Mb) of the Apis mellifera genome. The TEs are significantly smaller in Apis cerana than in Apis mellifera [Bombus terrestris and Bombus impatiens, respectively, and most of them were retrotransposons, of which Gypsy was the most common element. The main types of DNA transposons are TIRs of mariner, which account for 1.6% and 2.7%, and their abundance is higher than that of Apis cerana and Apis mellifera [Transposons can generate new genes through genome rearrangement and overexpression, which play a role in the behavioral diversification of oneybees . Given toneybees ,14. The equences . In the se to 8% . DNA trais class . A recenmost TEs . The DNAellifera . In a stellifera . In addiellifera ,75,76,77Tc1/mariner and two families of pogo, which suggests that the genome of some bees represents high diversity of Tc1/mariner and pogo transposons. In our study, the genomes of 37 bee genomes were rich in pogo and Tc1/mariner transposons, and included nine different transposon families: DD29-36D/Tigger, DD35-36D/Fot, DD34D/mariner, DD34E/Tc1, DD36E/IC, DD37D/maT, DD38E/IT, DD39D/GT, and DD41D/VS. Among all transposon families discovered to date, DD34D/mariner is the most widely distributed and appears in almost all bee genomes. In addition, DD34D/mariner is also widely distributed in nature and has been reported in all species [As expected, in our analysis, the transposon diversity was also higher for bumblebees than honeybees. We detected at least seven families of  species ,80,81,82Tc1/mariner and pogo transposons do not display significant amplification in these lineages. This is consistent with previous findings that most Tc1/mariner is detected with low genomic coverage [mariner in the genomes of Apis mellifera, Apis mellifera carnica, Apis mellifera caucasia, Apis mellifera mellifera, and Euglossa dilemma. The evolutionary dynamics analysis showed that the DD34D/mariner elements of these five genomes are very young, and we speculate that these elements may remain active in the genomes of some species. The European honeybee is an important economic animal introduced into China in the last century, where there is a considerable amount of breeding. Active transposon elements may play an important role in the genome evolution and subspecies differentiation of European honeybees, and their existence raises the possibility of molecular operations on honeybees. In addition, the number of newly discovered families of the pogo and Tc1/mariner superfamily continues to increase as more genomic sequencing data are obtained, and this trend indicates that the diversity of the pogo and Tc1/mariner superfamilies may be much larger than the currently known families.It is generally believed that the copy number is related to transposon activity and that a genome with more intact transposon copies, which include the full-length transposase (no frameshift mutation) and the flanking TIRs with very high identity, usually reflects a recent invasion activity, suggesting that some copies may be still active . We examcoverage ,71. In aTc1/mariner and pogo transposons in 37 species, for a total of 164 transposons. Interestingly, we found that the genomes of some solitary bees were rich in DNA transposons. For example, Habropoda laboriosa exhibited DD29-36D/Tigger, DD34D/mariner, DD37D/MaT, DD41D/VS, DD34E/Tc1, DD36E/IC and DD38E/IT transposons; Dufourea novaeangliae exhibited DD29-36D/Tigger, DD34D/mariner, DD35-36D/Fot, DD34E/Tc1, DD36E/IC, DD37D/MaT, DD38E/IT and DD41D/VS transposons; and Colletes gigas exhibited DD29-36D/Tigger, DD35-36D/Fot, DD34D/mariner, DD34E/Tc1, DD36E/IC, DD37D/maT, DD38E/IT, and DD41D/VS transposons. Social bees exhibited significantly fewer transposons than solitary bees. For example, the Tetragonula genus exhibited only two transposon subfamilies, DD29-36D/Tigger and DD34D/mariner. In Apis genus, there are also two families of transposons (DD34D/mariner and DD41D/VS) that appear in the genome of honeybees. This seems to be related to the living environment. Solitary bees act alone and their long-term migration and living environment are more complicated and unstable, whereas social bees live in a group involving social activities and their living environment is more stable [Bombus genus exhibited four families, DD29-36D/Tigger, DD34D/mariner, DD41D/VS, and DD34E/Tc1. Interestingly, Bombus genus are a group that once transformed from solitary bees to social bees, which seems to further verify that the content of transposon may be related to the living environment.In this analysis, we detected a total of nine families of e stable . On furtApis mellifera, Apis mellifera carnica, Apis mellifera caucasia, and Apis mellifera mellifera exhibited a complete DD34D/mariner element (full-length and complete ORF). However, only the complete ORF of DD34D/mariner was exhibited by Apis cerana, Apis cerana cerana, Apis cerana japonica, Apis dorsata, Apis florea, and Apis mellifera intermissa, and the boundary could not be determined. Compared with its close relative, the European honeybee, the Asian honeybee seems to have a stronger selection of transposons in the genome. It is possible that the drones that develop from unfertilized eggs and carry haploid chromosomes experience strong selective pressure on some active elements [VS, we only found that Apis mellifera, Apis mellifera carnica, Apis mellifera caucasia, Apis mellifera mellifera, and Apis dorsata have the complete full-length transposon sequence, but no complete ORF was found. Moreover, Apis cerana, Apis cerana cerana, and Apis cerana japonica did not exhibit any DD41D/VS transposon elements. It seems that DD41D/VS may be an ancient invasion and that, during long-term genome evolution, European honeybees gradually lost their complete copy and Asian honeybees completely lost the entire transposon. Finally, some studies have noted that a host contains an endogenous enzyme system that can silence the transposon or some virus expression, such as RNA interference [We also found another interesting phenomenon. elements . In our rference . HoweverTransposons are parasitic DNAs whose only role is to replicate and propagate. When a transposon invades a host, the germline genome must be colonized to ensure that it remains in the population. This then increases the copy number , and theTigger. To find the HT origin of the DD29-30D/Tigger transposon, we performed Blast searching of this transposase in Dufourea novaeangliae in the NCBI nucleotide collection (nr/nt) database. The complete DDD spacing (DD30D) catalytic domains were detected in Nosema bombycis, Strongyloides stercoralis, and Ctenocephalides felis. Interestingly, these three creatures have parasitic abilities: Nosema bombycis is a parasite of silkworm, Strongyloides stercoralis is parasitic in humans, and the host of Ctenocephalides felis is the cat. These species may serve as potential vectors for Tigger transposons that have invaded the bee genome at a certain time; if so, this strongly suggests the existence of a host–parasitic relationship in bees. These findings suggest that the host–parasitic mode may also be the primary mode of HT of Tigger transposon.In this study, although most transposons did not show obvious HT signs, the potential HT traces were detected for DD29-30D/pogo and Tc1/mariner family transposons in 37 sequenced Apoidea genomes. In general, pogo and Tc1/mariner show high diversity in most species, except for a few honeybees, but have a low abundance. In addition, only DD34D/mariner has a high copy number in several species, appears as a complete structure, and may have potential activity. Finally, our results also show that DD29-30D/Tigger may experience HT events, and we speculate that they may have invaded their common ancestor before some species formed.Our research provides, for the first time, information about the distribution of