N = 103 late-adolescents with schizophrenia, ADHD, ASD and healthy controls took a serial visual search task, while their eye movements were recorded. Patients with schizophrenia presented the greatest level of impairment across different phases of search, followed by patients with ADHD, who shared with patients with schizophrenia elevated intra-subject variability in the pre-search stage. ASD was the least impaired group, but similar to schizophrenia in post-search processes and to schizophrenia and ADHD in pre-search processes and fixation duration while scanning the items. Importantly, the profiles of deviancy from controls were highly correlated between all three clinical groups, in line with the continuum idea. Findings suggest the existence of one common neurodevelopmental continuum of performance for the three disorders, while quantitative differences appear in the level of impairment. Given the relevance of cognitive impairments in these three disorders, we argue in favour of overlapping pathophysiological mechanisms.Disorders with neurodevelopmental aetiology such as Attention-Deficit/Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD) and Schizophrenia share commonalities at many levels of investigation despite phenotypic differences. Evidence of genetic overlap has led to the concept of a continuum of neurodevelopmental impairment along which these disorders can be positioned in aetiological, pathophysiological and developmental features. This concept requires their simultaneous comparison at different levels, which has not been accomplished so far. Given that cognitive impairments are core to the pathophysiology of these disorders, we provide for the first time differentiated head-to-head comparisons in a complex cognitive function, visual search, decomposing the task with eye movement-based process analyses.  With the advent of the DSM-5 , renewedDespite its neurodevelopmental origin , schizopHowever, genomic studies identified rare risk alleles common among NDD, including Autism Spectrum Disorder (ASD), Attention-Deficit/Hyperactivity Disorder (ADHD) and schizophrenia, leading to a model in which NDD are represented in a neurodevelopmental and aetiological continuum, expressing the severity, timing, pattern of abnormal brain development and resulting in functional abnormalities .Further commonalities include shared environmental risk factors, higher frequency in males, frequent comorbidities and overlapping mechanisms at multiple levels. Phenotypically, impairments in various executive functions, in rapid information processing and sustained attention and difficulties in motor coordination are common across the three disorders . MoreoveAmong the phenotypic commonalities cognitive impairments play a prominent role as they are in all these disorders crucial for functional outcome and may pinpoint part of the underlying pathophysiology.Visual search (VS) is a frequently studied paradigm in cognitive research and includes the dichotomy between parallel and serial search. When the target is easily distinguishable from non-target items (“distractors”), items are searched in parallel and search efficiency is independent of the number of distractors. Conversely, when the target is hardly distinguishable from distractors, attention is narrowed down, items are searched in serial fashion and search efficiency decreases linearly with the increase in the number of distractors.parallel search [serial search characterises patients with schizophrenia [ Participants with schizophrenia, ADHD or ASD show normal l search . By contophrenia , 11 or Aophrenia , especiaophrenia  and ADHDophrenia  first-deophrenia . Individophrenia  and theiophrenia , conversophrenia .process analyses of VS. Such analyses can be accomplished by eye movement recordings, providing a highly differentiated picture of VS performance, as will be shown here.A methodological commonality of the studies above is the exclusive use of manual mean reaction time (RT) and search rate, collapsing a complex cognitive behaviour into a single measure. In fact, multiple cognitive capacities are involved during serial search, including short-term memory, focus and shift of attention. Arguably, deficits in any of these sub-processes could lead to VS impairment, requiring their differentiation in VS is located within a research framework, where the measurement of eye movement during standard ocular-motor tasks and visual exploration tasks has contributed to the understanding of the complex underlying neuropathophysiology of NDD. Literature on basic saccade paradigms reported delayed latency, frequent inaccuracy and inhibition errors in the execution of volitional saccades across schizophrenia, ADHD and ASD . A less Based on the above, the present study investigated VS performance simultaneously in schizophrenia, ADHD and ASD, pursuing the following goals: (i) to determine the differences between clinical groups and of each clinical group with TD; (ii) to explore similarities between clinical groups in their deviances from controls.The study provides the following hypotheses: (a) patients with schizophrenia will show delayed responses and generalised increased ISV; (b) patients with ADHD will show slower manual RT alongside generalised increased ISV; (c) patients with ASD will outperform all other groups in processing speed, including less fixations and will show increased ISV; (d) patients with schizophrenia will present the overall most impaired performance, ASD the least; (e) profiles of deviancy from controls will be positively correlated between all clinical groups.The present study is the first “head-to-head” comparison of schizophrenia, ADHD and ASD in core aspects of cognitive proficiency providing process analyses of cognitive performance through eye movement recordings.r = 0.98 [Participants were 20 patients with schizophrenia , 28 with ADHD (18–23 years), 26 with ASD and 29 TD (17–23 years) . The illumination level was measured by a digital Peaktech 5035 light meter with range 0–2000 lx , maintained between 70 and 80 lx across participants. Eye movements were recorded binocularly at 1000 Hz sampling rate and 0.01° spatial resolution, using the EyeLink 1000 Plus . A thirteen-point manual calibration was used. Gaze positions were calibrated if gaze accuracy was within 1°. Before each trial participants performed a drift correction, ascertaining that gaze accuracy was within 0.5°. The VS task was presented during a 150-min session, including three 10-min breaks, as part of a battery of several other eye movement tasks. The order in which tasks were presented was counter-balanced across participants within each group through a balanced Latin Square, thus obtaining a constant task order across the four groups and preventing task order from being a confounding variable. Participants were rewarded for their participation with vouchers.Search displays consisted of 16 items, corresponding to 0.90° × 0.90° black outlined squares (line width 0.16°) with a 0.17° gap on one of the sides. Distractors had gaps on either left or right side, targets on either top or down side. Items were placed in a 4 × 4 grid (18° × 18°), target in eight out of 16 locations, four with shortest and four with longest distance from the centre of the grid, resulting in two eccentricities and thus different retinal visual acuities . TargetsAnalyses were performed on one eye’s data, depending on ocular preference and the eye trace quality. Despite binocular recording, we opted for monocular analysis because of the discrepancy in the eye trace quality between the two eyes in some participants. The decision on which eye’s data to use was based on the offline evaluation of first calibration, validation, drift corrections and additional possible calibrations alongside reported ocular preference. Saccades were detected through a velocity-based method . “Fixation” was defined as any period that was neither blink nor saccade. A blink was inferred any time the tracking of the eye was lost, resulting from occlusion of the eye by the eyelid. Only saccades with peak velocities above 25°/s and amplitudes greater than 1° were analysed. Responses after 8000 ms were counted as errors. Anticipatory responses were initiated prior to, or within 80 ms from search grid appearance.t tests allowed for comparisons of each clinical group with TD, while non-predicted pair-wise comparisons were computed using post-hoc Tukey’s test. Repeated measures ANOVA allowed to explore interactions between GROUP and TARGET ECCENTRICITY . Results remained essentially the same when age and RSPM scores were controlled for statistically. Therefore, only results without covariates are reported. Gender was also not included as a covariate as control analyses comparing male and female participants revealed no significant differences. To control for the potential effect of antipsychotic medications in the SCZ group, each dependent variable was correlated with the antipsychotic dose, using Pearson’s r. To do so, the medication dose was converted to chlorpromazine equivalents (CPE) per day [Dependent variables are described in Table  per day , 40. Forr to precise the degree of similarity of profiles of deviancy from controls between pairs of clinical groups. Each vector reflects the between-group difference (t test scores) of each clinical group from TD across the set of dependent measures, thus obtaining three vectors . For all measures of SD, these t tests were based in addition on the residuals after controlling for the corresponding means, thus addressing the known problem of correlations between central tendency and dispersion. Finally, and to investigate differences in the degree of impairment between clinical groups, we defined vector levels. To do so, the average of each of the three vectors was used to quantify the (average) level of impairment of each clinical group by calculating the paired-sample t test between pairs of vectors.Importantly, we ran vector correlations using Pearson’s α = 0.05 was adopted, Cohen’s d quantified effect sizes. Analyses were performed with SPSS, Version 24 .For the ANOVAs statistical analyses, a significance level of Descriptive statistics are reported in Table ts < 0.1). While all trials associated with a correct response were classified as valid and thus included in the analyses, the average percent of time in which the eye was missing was rated 2 ± 4% for TD, 15 ± 15% for SCZ, 8 ± 11% for ADHD and 7 ± 16% for ASD, significantly higher in SCZ and ADHD than TD, only marginally higher in ASD than TD, while not discriminating clinical groups.Manual RTs were slower and search durations longer on trials with far targets, while no other differences were found. Despite accuracy being above 90% across groups, SCZ were more error prone than TD, ADHD or ASD, whereas the other groups did not differ  = 0.52, p = 0.02, d = 1.20, η2 = 0.27), while for any other dependent variable non-significant correlations with small to intermediate effect size (0.04 ≤ r(20) ≤ 0.35, 0.08 ≤ d ≤ 0.74) were found.Within the SCZ group, correlation analyses between each dependent variable and CPE revealed that only the mean initiation of search significantly correlated with antipsychotics’ dose  and, even more so, ASD , while ADHD were more impaired than ASD . Vector correlations showed that the profiles of deviancy from controls for SCZ and ADHD (r(14) = 0.683, p = 0.007, d = 1.87, η2 = 0.47), SCZ and ASD (r(14) = 0.836, p < 0.0001, d = 3.04, η2 = 0.7) and ADHD and ASD (r(14) = 0.745, p = 0.002, d = 2.23, η2 = 0.55) were highly positively correlated , target locations (eight out of 16) and number of targets (only one), while disruption in the VS performance in ADHD has been circumscribed to the easiest and most difficult task conditions [, target Finally, search duration and scanning time were shorter than typical in ASD, expressing enhanced perceptual discrimination between target and distractors  or atypiSCZ, ADHD and ASD shared longer and more variable single fixation duration. Conversely, while SCZ and ADHD presented typical frequency of fixations, of fixated distractors and of total distance covered, ASD executed the smallest number of fixations, gazed less distractors, covered a smaller search area, compared to any other group. According to Elahipanah et al.  serial sProlonged single fixation duration in ADHD suggests that extracting relevant characteristics from search items is more time consuming than in TD, while typical frequency of fixations and fixated distractors indicate preserved visual guidance processes. Noteworthy, and differently from SCZ, fixation duration paralleled typical duration of search and scanning time, suggesting that ADHD might have had more cognitive resources than SCZ to perform the task efficiently, while opting for a focal search strategy, like SCZ. Only two other studies have assessed VS in children with ADHD including fixation-related measures , 63. CuiAmong all groups, the shortest search and scanning time duration was found in ASD. While longer fixation duration point to suboptimal rather than enhanced central discrimination, the additional time on item in foveal vision, alongside adequate guiding attention towards the next item might have been determinant for the success in the task. Reduced frequency of fixations, fixated distractors and scanning pattern are in accordance with the observation that individuals with ASD can be disproportionately affected by contiguous items close to the current fixation, independently of their relevance (target versus distractors) . It is pIn contrast to the current finding, shorter fixation duration in ASD has been reported using the Embedded Figure Task (EFT), where participants are required to find a target inside a figure , 67, 68.More generally, locally oriented processing style is manifest in multiple ways in ASD. It appears to be associated with symptoms of stereotyped and restricted behaviours, possibly mediated by the association of local processing and increased attention to details in daily life , 71 and Increased ISV in SCZ emerged from manual and eye movement measures and across search sub-phases. The strength of this finding confirms results from the literature, which shows increased ISV across fast decision tasks associated with various levels of cognitive demands , 76. OveIncreased ISV in search initiation, post-search and single fixation duration was found in ASD, while they were the least variable group during search and scanning time. Despite ISV has been disproportionately less studied in ASD than ADHD and schizophrenia, literature that controlled for comorbidity between ADHD and ASD, comparing the performance of participants with ADHD only, ASD only and a comorbid group, concluded that the task-general increase in ISV reported for ADHD and comorbid groups does not extend to ASD , 80–82. A possible explanation of differential ISV results in the three groups was proposed by Dinstein et al. , who hypIncreased ISV in adults with schizophrenia  and chilResults from the process analyses enabled by eye movement recording during visual search highlight a pattern of both similarities and differences between SCZ, ADHD and ASD. While the slowing and trial-to-trial variability in SCZ is manifest across all sub-phases of the VS performance, it is specific for some in ADHD and is even reversed in ASD during search. Similarly, results on fixation-related measures highlight overlaps and dissociations in the way in which search items are processed.At a cognitive level, deficit in attention sub-processes of focus and disengagement, as well as in decision processing, are central to the three disorders . AccordiAt a pathophysiological level, similarities in cortical changes between SCZ, ADHD and ASD have been documented. Among the most relevant networks, the fronto-striatal system, responsible for decision-making processes requiring adaptive responding , the fronto-parietal network, involved in top-down control, and the DMN, associated with task-irrelevant mental processes, have robustly been shown to be involved in ADHD, ASD and schizophrenia , 93. Ther ≤ 0.84) between the profiles of impairment in the clinical groups may suggest that they show the similar quality of cognitive impairment despite their different phenotypes.Similar profiles of impairment  between the clinical groups were also revealed by high vector correlations that corresponded to large effect sizes and were also found after removing trivial statistical dependencies between variables. If “impairment” is interpreted as a qualia that manifests in different cognition aspects, thus creating a profile of cognitive deviancy from “normality”, the substantial correlations (0.68 ≤ d ≤ 1.33). If we consider a “continuum” as a quantitative grading of the same qualia, the present results suggest that patients with ASD, ADHD and SCZ take different positions on the same continuum. The coexistence of commonalities and differences between ASD, SCZ and ADHD suggests the multidimensionality of such continuum, re-imagined as a spectrum of an underlying loss of function  and gain of function .In this continuum, SCZ showed the greatest level of impairment, ASD the smallest (0.57 ≤ Vector correlations like the current ones depend upon various aspects on the specific tasks and measures included, implying that replication across different measures and tasks is a precondition for generalizability of the present findings. Moreover, although in the current study vector correlations were particularly high, future studies will have to explore also potential moderators of vector correlation profiles, such as psychometric reliability. Finally, the validity of the vector correlations in this context would be corroborated further if patterns of negligible or even negative correlations between different clinical groups could be found.Some limitations should be noted. First, the size of the SCZ group was small, requiring replication. Second, SCZ were on current antipsychotics, whose effects cannot be excluded. Third, fatigue could have had an effect on the performance, given the long session duration.The present results found support for a pattern of similarities and differences between schizophrenia, ADHD and ASD. VS impairments seem to reflect a core generalised cognitive dysfunction in schizophrenia resulting from the three constructs of processing slowing, increased ISV and local processing bias. However, this finding was not entirely specific to schizophrenia, as ADHD and ASD also presented similar local bias and increased ISV in the initial stage of search, ASD in the post-search stage too. While increased focal attention in schizophrenia contributes to a suboptimal performance, it emerges as a successful strategy rather than a deficit in ADHD and is even advantageous for a speeded performance in ASD. Conversely, processing speed dissociates the three clinical groups being suboptimal in schizophrenia, enhanced in ASD, typical in ADHD. ISV has shown to be a powerful measure in dissociating reaction time of ADHD versus TD , 96 and


The descriptive classification Attention-Deficit/Hyperactivity Disorder (ADHD) is often mistaken for a disease entity that explains the causes of inattentive and hyperactive behaviors, rather than merely describing the existence of such behaviors. The present study examines discourse on ADHD to analyze how authors passively and actively contribute to reification—a fallacy in which a concept is represented as a thing existing on its own.Critical Discourse Analysis and Qualitative Content Analysis of academic textbooks, scientific articles, websites and videos were used to analyze how ADHD is reified.The analyses reveal four ways in which inattentive and restless behaviors are presented as an entity by means of the ADHD classification: language choice, logical fallacies, genetic reductionism, and textual silence. First, language choice, such as medical jargon and metaphors aid in representing ADHD as a disease entity. Second, several logical fallacies do the same, including the relatively unknown “ecological fallacy” that refers to the erroneous belief that average group findings, such as average brain size of groups of those with an ADHD classification, can be applied on an individual level. Third, genetic reductionism is often achieved by overstating the results of twin studies and being silent about the disappointing molecular genetic research. Such textual silence is the last identified mechanism of reification and includes instances in which societal factors that affect the ADHD construct are often omitted from texts, thereby obscuring the extent to which ADHD is a limited heuristic.It is essential that discourse communities do not repeat these four ways of reifying behavior and social relations into an alleged entity with the acronym ADHD. The errors and habits of writing may be epistemologically violent by influencing how laypeople and professionals see children and ultimately how children may come to see themselves in a negative way. Beyond that, if the institutional world shaped to help children is based on misguided assumptions, it may cause them harm and help perpetuate the misguided narrative. To counter the dominant, reifying and medicalizing view, guidelines such as the recently published “Dutch ADHD Psychoeducation Guidelines” might be helpful. In a study of children’s views on Attention-Deficit/Hyperactivity Disorder (ADHD), Singh  reports facere) a “thing,” (from the Latin word “Res”). The children quoted above seem to understand ADHD as a thing, a concrete disease entity inside their bodies. Reification, also known as a “fallacy of misplaced concreteness”  itself; the psychiatric handbook that defines all psychiatric disorders. The fourth edition in particular is conscious of its limitations. The guidebook states that most of the classifications in the DSM are exactly that: “valuable heuristic constructs” instead of “well-defined entities that describe nature exactly as it is” .Fortunately, the problem of the reification of the DSM’s heuristic constructs is occasionally addressed. For instance, Hyman , the forstatus quo” However, Hyman does not explicate beyond the “nominal fallacy” to describe exactly how language affects reification. The present research aims to address the issue of reification in mental healthcare by examining the construct of ADHD. This study begins with the research question: what discursive elements reify the behaviors that fall under the ADHD classification?Critical Discourse Analysis (CDA) offers a suitable theoretical framework for answering the above research question as it is concerned with both discourse and reification. CDA mostly relates reification to nominalization  butAs qualitative content analysis does not take a clear epistemological stance, it seems important to clarify ours. Our research is rooted in “weak constructionism,” which assumes that a certain phenomenon, such as behaviors that are interpreted within a given cultural context, can have a material basis . Yet, the manner in which people discuss such a phenomenon is socially constructed . In the This is a critical review, which differs from e.g., a systematic review by primarily intending to spark a conceptual discussion more than pretending to have a systematic and quantifiable empirical base , on whiOur analysis revealed roughly four ways in which the abstract DSM-definition of ADHD is reified into a concrete disease: language choice, logical fallacies, genetic reductionism, and textual silence. The assertion that language choice is important in mental health-care is not new. actions into discrete or countable entities in the form of nouns , 22. In motives for standing up in a classroom instead of  causes, medical laden nouns often fall short of representing human behavior, while contributing to reifying these behaviors into medical disease entities. For this reason, Dehue . ADHD, like a meat-cleaver, just split your brain in half.” , blackboxing”  and neurochemistry  as the basis of the ADHD construct are hampered by all the aforementioned problems: biased sampling, only small group differences, no particular pattern of brain activity being necessary of sufficient for an ADHD classification and inconsistency through time. However, these studies are burdened further by a lack of consistency and reliability than neuro-anatomical studies. Brain activity is highly variable and it is “unknown whether the same findings (…) would be found one hour later, one day later, or one year later following the original scan” What we see on the image are two individuals, one from the case and one from the control group whose brain activity has been measured during certain tasks. The measured numerical values—transferred to colors based on thresholds set by the researchers—display that during the test the two individuals’ brain activities were different . HoweverAdditionally, for the construction of the characteristic—and widely dispersed—photo-like images of the alleged ADHD brain type it is a standard practice to select extreme examples from the already extreme samples that comprise the case and control groups Another common logical fallacy that can reify ADHD is circular argumentation. For example, Biederman and Faraone  state “Acorrelated to the very behaviors that define these disorders. For example, the following example comes from an article in the Journal of Abnormal Child Psychology:Another example of circular arguments occurs when behaviors associated with ADHD are linked to other categories of mental disorders. When two or more categories are used to describe children’s behaviors, through multiple diagnoses, this is commonly referred to as “comorbidity,” a medical term that denotes “Existing simultaneously with and usually independently of another medical condition” . ADHD is“Parents and teens in the ADHD/ODD group rated themselves as having significantly more issues involving parent–teen conflict, more anger during these conflict discussions, and more negative communication generally, and used more aggressive conflict tactics with each other than did parents and teens in the CC [control] group.” The researchers’ findings that ADHD and ODD are associated with the behaviors they describe illustrate circular logic. Nieweg , p. 693]936), p. Another common way in which ADHD is reified in literature is by confusing correlation with cause. For example, several studies show that prison inmates are often restless and have attentional problems –51. When“Adults with ADHD are at increased risk for unemployment, sick leave, coexisting disorders, abuse, and antisocial behavior leading to conviction (p. 1).”Post hoc, ergo Propter hoc”: after this, therefore because of this In this example, readers have no way of knowing why Sean has not reported about the broken paw. He might not have realized it, he might have felt ashamed that he dropped it by accident, or he might not have cared too much. In any case, it is unclear how this example should clarify anything in relation to ADHD because the behaviors do not represent any of the criteria for ADHD. The passage apparently should attest to the seriousness of ADHD and can reify by emphasizing the abnormality and problematic nature of Sean’s behavior.When examining how textbooks used in university teacher educator courses depict ADHD, Freedman  found siHeritability—mostly estimated on the basis of behavioral similarities and differences between identical and fraternal twins, is often claimed to be high. In this case no DNA material whatsoever has been studied. Heritability is not to be mistaken with inheritance, based on molecular genetic studies. In such studies, DNA material is analyzed. Inheritance refers to the transfer of genetic information from parents to children. However, as there are no clear genetic markers that can predict ADHD behaviors to any substantial degree, the established inheritance of ADHD is in fact very low. Initially, candidate-gene studies claimed small correlations between some genetic variants and ADHD behaviors. However, the finding of a mere 3.3% variance that seven of the best-established genetic variants could allegedly explain  do the same. Genetic reductionism happens by overstating the results of twin studies while being silent about the disappointing molecular genetic research. Such textual silence also takes place when important information like the relative age effect or the impact of poverty and overcrowded classrooms are not mentioned.As stated in the method section, this research has mainly focused on identifying discursive mechanisms of reification. This theoretical orientation comes at the expense of the potential of Qualitative Content Analysis (QCA), which is also very suitable for quantification and estimating of, in our case, the prevalence of certain identified mechanisms of reification in a given dataset. This fell outside of our research goal but for potential future studies, we refer to our earlier studies of scientific textbooks . FuBerger and Luckmann  state thThe effects of the reifying discourse surrounding ADHD go far beyond children’s own perception as suffering from a ‘disease.’ How social institutions, such as schools, understand and respond to children rests upon ADHD being constructed, or reified in discourse, as a disorder that some children have and others do not. Through literature such as research articles, textbooks, websites, TV-Programs, and even books for children The suggestion of dysfunctional brains—based on small group differences, inconsistently found in brain studies of ADHD—and other reifying mechanisms that we have identified in this paper, can contribute to “epistemological violence.” Epistemological violence is what Teo  describeReification is a necessary mechanism to address when countering discursive practices that result in epistemological violence. The misrepresentation of scientific knowledge, which arises when a heuristic such as ADHD is portrayed as a discrete entity, necessitates that authors who report their own research and the work of others do so with awareness of the pitfalls of reification. It is essential that discourse communities do not repeat harmful errors and habits of writing that can influence how laypeople and professions see children, and how children may come to see themselves. More thoughtful language and logic is needed that can encourage a more transparent approach to discussing the current state, and limitations of scientific knowledge.de facto agent of the status quo.”Berger and Luckmann  abstain More financial and self-serving motives for medicalization and reification are also subject of longstanding debates, for instance in relation to pharmaceutical “disease mongering” . A vividHowever, the discourse surrounding medicalization and psychiatrization points to much wider influences. For instance Conrad already in 1975 stated that “the medical profession may not have entirely sought this [medicalizing] role.” And although he adds that “its members have been, in general, disturbingly unconcerned and unquestioning in their acceptance of it” ,Such a view makes psychiatry more of a complicit actor in medicalization, but still focuses mostly on “top-down” actors. More contemporary studies on medicalization and psychiatrization discuss discursive practices in which classifications become self-fulfilling prophecies in recursive, discursive “looping” effects . These “The latter begs the underlying question “To the degree that diagnoses and biological explanations do provide an initial excuse for the kind of person one is, the most urgent question is why increasing numbers of people apparently need such an excuse” . To answstatus quo.Given a few exceptions, quantitative data on how often these reifying mechanisms occur is lacking. However, given the ease with which flawed information can be found, there seems to be an abundance of misinformation spread around concepts such as ADHD -including through reification in academic textbooks , 87 and The original contributions presented in this study are included in the references, further inquiries can be directed to the corresponding author.SM did the qualitative analysis and wrote the first draft of the manuscript. JF and LB supervised the analysis and commented on the first draft of the manuscript. All authors contributed to manuscript revision, read, and approved the submitted version.


Attention-deficit/hyperactivity disorder (ADHD) is associated with negative life outcomes and recent studies have linked it to increased mortality. These studies have examined nationwide registers or clinic-referred samples and mostly included participants up until the age of 30. No studies have investigated mortality associated with subthreshold levels of ADHD symptoms. Our aim was to analyze mortality in a perinatal risk cohort of 46-year-old adults with childhood ADHD (cADHD) and milder childhood attention problems  compared with a group with similar birth risks but no or low levels of childhood ADHD symptoms (Non-cAP). Causes of death obtained from a national register were examined.n in the study was 839 .Mortality was analyzed with Cox proportional hazard models for all-cause mortality, cause-specific mortality , and age-specific mortality (under and over age 30). All models were adjusted with gender. The total By the age of 46, 11 (9.6%) deaths occurred in the cADHD group, 7 (3.2%) in the cAP group, and 20 (3.9%) in the Non-cAP group. The cADHD group had the highest mortality risk . Mortality was not elevated in the cAP group . Mortality in the cADHD group was mainly attributed to unnatural causes of death . The mortality risk in the cADHD group was sixfold before age 30 .Childhood ADHD was associated with a twofold risk of premature death by the age of 46 in this prospective longitudinal cohort study. Our results corroborate previous findings and the morbidity of ADHD. Subthreshold levels of childhood ADHD symptoms were not linked to increased mortality. Our results suggest that mortality risk is higher in young than middle adulthood. Future studies should examine mortality associated with ADHD in different ages in adulthood to identify those in greatest risk of premature death. Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder affecting 3%-5% of children  and apprThe association of ADHD and increased mortality has gained more research focus in recent years. Studies on this association are yet few and have mainly been large nationwide studies Table . These sIncreased mortality associated with ADHD appears to be attributed to unnatural causes. In register studies accidents, suicides, and homicides have been the main causes of death in individuals with ADHD –8. CauseADHD symptoms follow a continuum and might fluctuate at different times during development causing an individual to reach a diagnostic threshold at one point in time but not at another –20. ADHDWe investigated the mortality of individuals with childhood ADHD or subthreshold symptoms associated with perinatal risks who were prospectively followed from birth up to an average age of 46 years. A group with similar perinatal risks but no or low levels of ADHD symptoms was also studied. Causes of death retrieved from a national register were also examined.n = 202) were excluded [This study is part of a larger prospective research project following a birth cohort. A total of 1196 infants with predefined perinatal risks born in a single maternity unit in Helsinki, Finland in years 1971–1974 were included in the study. The perinatal risks have been described in detail elsewhere, and included hyperbilirubinemia, birth weight < 2000 g, Apgar score < 7, respiratory distress, maternal diabetes, hypoglycemia, septicemia, or neurological symptoms , 24. Parexcluded .n = 115), childhood attention problems , and no or low levels of attention problems . Comprehensive data from childhood follow-ups were used to form the groups, comprising questionnaire information from parents, day care, and school, and clinical assessments by a pediatrician, speech therapist, and psychologist. Questionnaires and clinical assessments gathered information on physical and psychological development and included evaluations of hyperactive and inattentive behavior. Participants with ADHD were originally classified as having minimal brain dysfunction, hyperkinetic reaction of childhood, or attention deficit [The cohort was followed at 5 and 9 years of age and underwent comprehensive medical and developmental assessments . Latest  deficit , 28. As  deficit  using ch deficit . The cAP deficit , 30. TheDemographical factors related to early health and environment included in the study were gender, birth weight (in grams), Apgar score at 5 min, number of perinatal risks, and childhood socioeconomic status (SES). Perinatal risks were stratified into three classes: 1, 2, and 3 or more risks (range 1–5). Childhood socioeconomic status (SES) was defined as the highest median status of mother and father recorded in childhood assessments. Four groups based on parents’ occupational level were formed with level one representing the highest status.th, 2019. The deceased were stratified into two age groups, under and over age 30, as previous studies have mainly consisted of individuals up to a maximum average age of 30 , Finland and on the cause of death from Statistics Finland on November 30V or partial eta squared depending on the analysis. Cox proportional hazard regression models were used to analyze survival in childhood ADHD groups. Time was calculated as years from date of birth to date of death or to the end of follow-up, November 30th, 2019. The unadjusted model included childhood ADHD status. Gender was entered into an adjusted model as a potential covariate. One value for SES was missing and was imputed with the median of the childhood group. Age-specific survival (under and over 30) was analyzed with separate Cox proportional hazard regression models for these age groups adjusted by gender. Cause-specific mortality for natural and unnatural causes of death in different childhood group were likewise analyzed with adjusted Cox proportional hazard regression models with gender as a covariate. Statistical analyses were conducted using IBM SPSS software, version 26.Descriptive characteristics of the study group were analyzed with chi square tests for contingency tables and ANOVAs for continuous variables. Bonferroni corrections were applied to pairwise analyses due to multiple comparisons. Effect sizes were calculated as Cramer’s SD = 1.15; range 44–48) and there were no differences in age between the childhood groups (p = 0.52).Table p = 0.016. There were no significant differences in birth weight, Apgar score, number of birth risks, or childhood SES between the deceased and alive. Seven deaths had occurred before age 30 in the cADHD group (63.6%), two in the cAP group (28.6%), and four in the Non-cAP group (20.0%).A total of 38 deaths occurred in the entire cohort during the follow-up between ages 5 and 46. Nearly 10% of the cADHD group had deceased compared to 3%–4% in the other groups (Table p = 0.013). The HR remained similar for the cADHD group in the adjusted model (Table p = 0.035). Due to gender being significant in the adjusted model, we added the interaction of gender and childhood group to the model, but this interaction was not significant (p = 0.9). Mortality risk was over sixfold in the cADHD group for age-specific mortality before age 30 (Table p = 0.11).In the unadjusted Cox regression model childhood ADHD predicted survival .Cause of death was recorded in 37 out of 38 cases. One cause of death remained unknown in the cADHD group (death abroad resulting in register data not being available). The cause of death was unnatural in 8 out of 10 cases (80%) in the cADHD group, 5 out of 7 cases 71.4%) in the cAP group, and 11 out of 20 cases (55%) in the Non-cAP group. Causes of death in the childhood groups are presented in Table % in the Childhood ADHD was associated with increased mortality in this prospective cohort study over 46 years. Deaths in the cADHD group were mostly attributed to unnatural causes and were likely to occur in young adulthood. Childhood subthreshold ADHD symptoms were not associated with increased mortality.Childhood ADHD was associated with over a twofold increase in mortality risk compared to a group with no childhood ADHD or subthreshold symptoms up to age 46. Our results support findings from large nationwide studies that have found an association between ADHD and increased mortality . The twoThose in the cADHD group were more likely to die younger than the remaining cohort with over 60% of deaths occurring before age 30. Mortality risk for under age 30 was over sixfold in individuals with childhood ADHD whereas mortality was not increased in the age group of 30 to 46 years. No deaths occurred in the cADHD group in childhood, implying that adolescence and young adulthood might be a period of high risk for those with childhood ADHD. In a Swedish register study of a population of more than 2.6 million, 40 individuals with ADHD had died before the age of 17 . We did The cause-specific mortality risk for unnatural death was higher in the cADHD group compared to the other groups. This risk was over twofold and of similar magnitude as the all-cause mortality risk. Our results support the results of studies that have found greater risk of death due to unnatural causes, especially unintentional injuries and suicides in individuals with ADHD compared to comparison groups , 6–8, 16We found no association between subthreshold ADHD symptoms and increased risk of mortality. Prior studies have demonstrated that subthreshold ADHD is linked to high morbidity and functional impairment similar to that of the full disorder, including psychiatric comorbidity and educational and interpersonal dysfunction , 21, 22.The cohort in this study consists of individuals with various perinatal risks, which on their own might contribute to mortality risk. Preterm birth has been linked to increased risk of mortality in early to mid-adulthood , 32. A pThe main strength of this study is the long follow-up that allowed the examination of mortality associated with ADHD in a prospective longitudinal setting to a later age than any previous studies. Another strength is the investigation of subthreshold ADHD symptoms. To the best of our knowledge, there are no other studies on the mortality associated with non-diagnostic levels of ADHD symptoms. The childhood ADHD group was homogenous due to similarity in perinatal and environmental background  and due to not being medicated for ADHD. As the ADHD group was not clinic-referred for ADHD, there was no bias related to access to diagnosis.There are some possible limitations regarding our study. Due to small sample size, we were unable to analyze the effect of all different causes of death in the childhood groups. Information on psychiatric comorbidities was not available and we could not examine comorbidities as possible confounders in mortality. However, in another study of the cohort, we did not find differences between the childhood groups in self-reported alcohol consumption or symptoms of depression and anxiety . MoreoveIn conclusion, childhood ADHD is associated with a twofold mortality risk by age 46 in a longitudinally followed cohort of individuals with perinatal risks. This risk was higher in young adulthood and deaths were mostly attributed to unnatural causes. Subthreshold levels of childhood ADHD were not associated with increased risk of death. Our results corroborate the morbidity of childhood ADHD during the lifespan. Even though further research is needed, our results suggest that especially young adults with childhood ADHD are at greater risk of premature death, which calls for preventative measures to be aimed at this age group.


Attention-deficit/hyperactivity disorder (ADHD) is associated with a high prevalence of anxiety disorders in children and adolescents. The reasons for this association are poorly understood. Preliminary findings with young adults have suggested that executive functions and functional impairment may mediate the relationship between symptoms of ADHD and mixed anxiety and depressive symptoms. The objective of this study was to explore whether ADHD symptoms, executive functions and functional impairment predict anxiety in a clinical adolescent population. In addition, we investigated the possible mediating role of executive functions and functional impairment in this relationship.One hundred adolescents with ADHD and their parents completed the ADHD Rating Scale IV (ADHD RS-IV), the Behavior Rating Inventory of Executive Function (BRIEF), and the Weiss Functional Impairment Rating Scale (WFIRS) in relation to an RCT study. The adolescents also completed the Screen for Child Anxiety-Related Emotional Disorders (SCARED). Analyses were conducted using regression and a serial multiple mediator model.In the regression analyses, parent-rated ADHD symptoms were unable to predict anxiety, but ADHD inattention symptoms predicted anxiety in the self-ratings. Executive dysfunction and functional impairment predicted anxiety in both the parent- and self-reports. In the mediation analyses ADHD symptoms alone did not predict anxiety, but executive dysfunction mediated this relationship as expected. Functional impairment mediated this relationship indirectly through executive functions. The results were similar in the parent- and self- reports.The results pinpoint executive dysfunction as an important treatment target for alleviating anxiety in adolescents with impairing ADHD symptoms. Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders in childhood  and is cper se. This form of anxiety has been suggested to arise primarily when one's cognitive processing abilities are overwhelmed by the demands of the environment (Anxiety disorders (ADs) are among the most prevalent disorders in child and adolescent populations, and ADHD and AD are comorbid with each other in 25–50% of cases –10. Thisironment . Followiironment –21. EFs ironment . Dysfuncironment , interpeironment , and menironment . Althougironment , 29, theironment , 31.Previous research with university students with ADHD has demonstrated that executive functions may predict functional impairments. Dvorsky and Langberg  showed tTo our knowledge, only one published study has explored the relationship between symptoms of ADHD and mixed anxiety and depressive symptoms with a particular emphasis on EFs and functional impairment. In this study, EFs and functional problems explained 42 to 53% of the variance in mixed anxiety and depressive symptoms in a population of university students . A limitThe aim of the present study was thus to explore whether ADHD symptoms, executive dysfunction and functional impairment predict anxiety in a clinical adolescent population. Specifically, we hypothesize that the effect of ADHD symptoms on anxiety is to some extent mediated through EF or functional impairment see . Based oThis observational study was conducted in Mid-Norway. The data were derived from a randomized controlled trial (RCT) examining the efficacy of cognitive behavioral group therapy as a follow-up treatment in a sample of adolescents with ADHD who previously received a short psychoeducational intervention and were medicated but still presented impairing ADHD symptoms . We refeth edition (DSM-5). According to Norwegian ADHD guidelines . This information was retrieved from the participants‘ medical records. Nineteen percent reported that they had an education lower than elementary school or 1–2 years of high school (0–11 years), seven percent completed high school and/or 1 year of training after high school (12–13 years), thirty percent had an academy or university degree for up to 4 years (14–15 years), and nineteen percent confirmed an academy/ university degree for 4 years or more (16 years and more).The socioeconomic status (SES) of the participants refers to the highest level of education reported by one or both parents   was usedThe Screen for Child Anxiety-Related Emotional Disorders (SCARED)  was usedThe Behavior Rating Inventory of Executive Function (BRIEF)  assessesThe Weiss Functional Impairment Rating Scale parent-report (WFIRS-P) and self-report (WFIRS-S) versions  assess fWe conducted regression analyses to analyse the individual contributions of parent-rated and self-rated ADHD symptoms, executive dysfunction, and functional impairment to the severity of adolescent-rated anxiety symptoms in separate analyses. First, the ADHD RS-IV total score; the ADHD RS inattentive and the hyperactivity subscale scores; the BRIEF GEC, BRI and MI indices; and the WFIRS total score were entered one by one as independent variables, with the SCARED total score as the dependent variable. Second, to explore which of the subscales or indices from the ADHD RS-IV and the BRIEF questionnaire that predict anxiety the most while controlling for the other questionnaire subscale, we carried out two separate regression analyses: first with the two ADHD RS-IV subscales simultaneously and second with the two BRIEF indices simultaneously. Multicollinearity was checked to avoid high correlations (r =0.70 and above) between the independent variables, as recommended by Dormann et al. . The norwww.processmacro.org). The PROCESS command generates bootstrap confidence intervals (CIs) for all indirect effects as well as possible pairwise comparisons between indirect effects. We used 5,000 bootstrap samples. The ADHD RS total score was entered as the predictor variable (X), the BRIEF GEC score was entered as the first mediator (M1), and the WFIRS total score was entered as the second parallel mediator (M2)  see , 3. The Lydersen . StatistThe 100 participants included 57 females and 43 males; the mean age was 15.8 years (SD = 1.3). When collecting the data, ninety-one percent of the participants were stably taking ADHD medication. Nevertheless, sixty-six percent of participants met the DSM-5 criteria for an ADHD diagnosis (35% predominantly inattentive presentation and 31% combined presentation), and 33% presented subthreshold symptoms of ADHD . Fifty-three percent of the participants had at least one current comorbid condition; among them, 37% had an AD according to the DSM-5 criteria see .p = 0.002), the BRI (p = 0.010) and the MI (p = 0.003) significantly predicted anxiety, as did the WFIRS total score (p < 0.001).The results from the regression analyses using parent-ratings of the ADHD RS-IV, the BRIEF and the WFIRS to predict anxiety symptoms measured with the SCARED self-report, controlling for age and sex, are presented in In step 2 of p = 0.002). Among the BRIEF indices, the GEC, MI, and BRI predicted anxiety (p ≤ 0.001), as did the total score of the WFIRS (p < 0.001).The results from the regression analyses using self-ratings of the ADHD RS-IV, the BRIEF and the WFIRS to predict anxiety symptoms measured with SCARED, controlling for age and sex, are presented in In step 2 of p = 0.048); thus, a low ADHD symptom score significantly predicted more severe symptoms of anxiety when EFs and functional impairment were controlled for. The first indirect effect of only EF mediating the association between ADHD symptoms and anxiety was significantly positive . Thus, levels of ADHD symptoms predicted levels of executive dysfunction, which again mediated the severity of anxiety symptoms. The second indirect effect was through levels of functional impairment only, which was negative and non-significant . The third indirect effect of executive dysfunction and functional impairment in serial (X- M1- M2-Y) was positive and significant ; thus, the association between ADHD symptoms and anxiety seems to be mediated by EFs affecting functional impairment, which in turn mediates symptoms of anxiety. This was found regardless of age, sex, IQ, and SES.Regression coefficients presenting the direct effects between the parent-rated variables are presented in p = 0.007). The first indirect effect via executive dysfunction alone was positive and significant , while the second indirect effect via functional impairment alone was non-significant . The serial indirect effect of executive dysfunction and functional impairment on the association between ADHD and anxiety was positive and significant , and the results were similar to the analyses with the parent reports.Regression coefficients presenting the direct effects between the self-rated variables are presented in Children and adolescents with ADHD have an increased risk of comorbid ADs compared to their non-ADHD peers. In addition, anxiety symptoms tend to have an earlier onset, be more severe and be frequently associated with other psychiatric conditions , 55. AltAmong the EFs, both the global executive composite (GEC), the behavioral regulation index (BRI) and the metacognitive index (MI) were able to predict anxiety in both self- and parent-reports. Neither the BRI nor the MI index was significantly able to predict anxiety over and above the other BRIEF index when controlling for age and sex. The behavioral regulation index reflects both emotional dysregulation, mental inflexibility and impulsivity. An association between emotional dysregulation and anxiety would be expected. In addition, an association between mental inflexibility and anxiousness has previously been found in studies examining measures of shifting and updating using neurocognitive measures on clinical and non-clinical samples of anxious children and adolescents –59. ImpuThe metacognitive index includes cognitive functions such as working memory, task completion, planning and organization, and organization of materials, all skills strongly related to school performance and the attainment of future goals. As such, it is reasonable to link experienced difficulties in these areas with both low self-esteem and lack of control, which again may increase anxiousness. Finally, the functional impairment score, representing self-concept, social activities, school functioning, life skills and risky activities, predicted anxiety in both the parent- and self-reports. In sum, both executive dysfunction related to behavior regulation and metacognitive functions and functional impairment may be important to assess when working with adolescents with ADHD and comorbid anxiety.per se may lead to comorbid anxiety or mood disorders and difficulties in daily life. In the current study, ADHD symptoms alone were unable to predict functional impairment, but functional impairment predicted anxiety. Functional impairment was thus unable to mediate the ADHD-anxiety relationship by itself but acted as a mediator through EFs. Executive dysfunction has previously been linked to functional impairment in both school and social settings in children and adolescents with ADHD  were on ADHD medication when completing the questionnaires; thus, the results may not be representative of adolescents with ADHD who are not on medication. Second, the participants showed subthreshold ADHD symptoms, which may limit the generalizability to participants with more severe symptoms. Third, data on ADHD symptoms, executive functions and functional impairments were restricted to parent- and self-report questionnaires. The additional use of neurocognitive measures and computer tests to assess inattention symptoms and executive functions could have added valuable supplemental information in this study. Fourth, a high correlation between the main index scores see  indicateIn this study, ADHD inattention symptoms, executive functions and functional impairment predicted anxiety in a clinical adolescent population with ADHD symptoms. ADHD core symptoms were, however, not able to predict anxiety when controlling for executive functions and functional impairment in a mediation analysis. Executive dysfunction acted as a substantial mediator in this relationship, while functional impairment mediated this relationship only through EFs. This result pinpoints executive dysfunction as an important treatment target in alleviating anxiety in adolescents with impairing ADHD symptoms. Thus, the additional assessment of EFs using a broadband questionnaire such as the BRIEF parent- and self-report versions is recommended when assessing ADHD and comorbid disorders in adolescent populations. The results also suggest that adolescents with ADHD with normal EFs may have a lower risk of experiencing anxiety. These results improve our knowledge of the association between ADHD and anxiety in a clinical ADHD population. More studies are needed to replicate these findings across different age groups.The original contributions presented in the study are included in the article/The studies involving human participants were reviewed and approved by the Regional Committee for Medical and Health Research Ethics in Southeast Norway (2015/2115). Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.TN, PT, and SL supervised A-LH. A-LH drafted the paper and performed the statistical analyses with the supervision of SL. All authors contributed to the research design, provided substantial contributions to the paper, and read and approved the final version of the manuscript.The study was funded by a PhD grant to A-LH by the Regional Centre for Child and Youth Mental Health and Child Welfare (RKBU), Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU). The study received additional funding from the Child and Adolescent Psychiatric Clinic, St. Olav's University Hospital; the Regional Network for Autism, ADHD, and Tourette syndrome, Mid-Norway Health Trust; the National Research Network for ADHD, Ullevål University Hospital, Oslo; and the Regional Competence Network for ADHD, RKBU, NTNU.Authors A-LH, AS, and TN have received a speaker's fee and a travel honorarium from Medice during the last 3 years. Author PT has received speakers fee from Medice and Takeda within last 3 years. Author PT has received royalties from several publishers for books on ADHD and related disorders. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Sleep and Attention-Deficit/Hyperactivity Disorder (ADHD) have repeatedly been found to be associated with each other. However, the ecological validity of daily life studies to examine the effect of sleep on ADHD symptoms is rarely made use of. In an ambulatory assessment study with measurement burst design, consisting of three bursts (each 6 months apart) of 18 days each, 70 German schoolchildren aged 10–12 years reported on their sleep quality each morning and on their subjective ADHD symptom levels as well as their sleepiness three times a day. It was hypothesized that nightly sleep quality is negatively associated with ADHD symptoms on the inter- as well as the intraindividual level. Thus, we expected children who sleep better to report higher attention and self-regulation. Additionally, sleepiness during the day was hypothesized to be positively associated with ADHD symptoms on both levels, meaning that when children are sleepier, they experience more ADHD symptoms. No association of sleep quality and ADHD symptoms between or within participants was found in multilevel analyses; also, no connection was found between ADHD symptoms and daytime sleepiness on the interindividual level. Unexpectedly, a negative association was found on the intraindividual level for ADHD symptoms and daytime sleepiness, indicating that in moments when children are sleepier during the day, they experience less ADHD symptoms. Explorative analyses showed differential links of nightly sleep quality and daytime sleepiness, with the core symptoms of inattention and hyperactivity/impulsivity, respectively. Therefore, future analyses should take the factor structure of ADHD symptoms into account. People with attention deficit/hyperactivity disorder (ADHD) have self-regulation difficulties and frequently experience symptoms of inattention, hyperactivity and impulsivity ,2. TheseCurrent theories define self-regulation as dimensional in nature. According to this dimensional view, every person lies on a continuum between two extreme poles of high ADHD symptoms on the one side and high self-regulation in behaviour on the other side ,7. TakinRecent findings suggest that differences in self-regulation do not only exist between individuals  but ADHD symptoms also fluctuate within individuals  . AmbulatSleep is an important factor for cognitive and psychological functioning in daily life . Sleep iAccording to the state regulation model, children with sleep loss might not have the energy to adequately regulate their arousal and activation . A few sBesides the quality of night sleep, which might influence the regulation of attention and behaviour, there also might exist an effect of the current personal experience of tiredness during a specific moment of the day. Although this might seem paradoxical, children who are feeling sleepy could be more instead of less active than usual, as it indeed has been described by many parents . The feeThe overarching construct of sleep seems to be composed of several different sleep indicators like sleep duration, sleep efficacy, or sleep quality. These indicators in turn might be measured by calculating the hours of total sleep time, the number of awakenings, the time needed to fall asleep (sleep onset latency), and the subjective feeling of being rested in the morning . All of Another aspect of sleep is the feeling of being tired or sleepy during the day. According to a meta-analysis, this daytime sleepiness has shown higher correlations to school performance than sleep quality and sleep duration . This inConsidering the above-described research, we were interested in examining how self-reported nightly sleep quality, sleepiness over the day, and ADHD symptoms interact with each other on a between- as well as a within-person level in the daily life of German schoolchildren. ADHD symptomatology was defined on a dimensional level, therefore a general population sample was gathered to depict as much variance in the construct as possible. To account for fluctuations in the measured constructs, ambulatory assessment was used. Both constructs were examined through self-report. Sleep quality was defined by a combination of sleep onset latency and subjective sleep quality. Daytime sleepiness was assessed through indication of the activation level. In the current study, 10–12-year-old children were asked to report on their sleep, sleepiness, and ADHD symptoms on 18 consecutive days. These assessment periods were repeated three times, each time half a year apart, resulting in a maximum of 54 days of assessment. Such an ambulatory assessment not only decreases memory bias, but also ensures a high ecological validity , Burst 2: OR = 1.68, 95% CI , and Burst 3: OR = 1.43, 95% CI ). Moreover, with each day within a study burst the likelihood for missing values increased by up to 6% compared to the previous day .Within each study burst, missing values were more likely to occur on weekends compared to school days by up to 68% . Children reported medium to high sleep quality . Most variance was indicated for daytime sleepiness . Mean self-report of ADHD symptom levels in the sample was relatively low (Fluctuations of the variables can be inspected more thoroughly in γ12 = 0.18 (SE = 0.08), p = 0.03), which almost annulated a non-significant trend for this between-person association in Burst 1 (γ02 = −0.16 (SE = 0.09), p = 0.07). However, we found that ADHD symptoms decreased significantly during Burst 1 (γ01 = −0.27 (SE = 0.13), p = 0.04), with no significant changes in within-burst decrease rates across bursts. Also, children reported significantly lower ADHD symptom level at the beginning of Burst 3 compared to Burst 1 (γ01 = −0.25 (SE = 0.11), p = 0.02). The random intercept showed to be significant in the analyses, indicating significant differences in children’s initial ADHD symptom levels.To assess the association of sleep quality during the preceding night and ADHD symptoms during the school day, multilevel models were conducted. As can be seen in γ12 = −0.12 (SE = 0.06), p = 0.04), which almost annulated a non-significant trend for this between-person association in Burst 1 (γ02 = −0.16 (SE = 0.10), p = 0.11). However, the data indicated a negative within-person association of daytime sleepiness and ADHD symptoms in the initial study burst (γ02 = −0.04 (SE = 0.02), p = 0.01), with no significant changes in the subsequent bursts. This result suggests that in moments when participants felt more tired during the day they indicated less ADHD symptoms, therefore contradicting our hypothesis. Also, we again found significant decreases in ADHD symptom levels throughout each study burst, as well as overall decreased symptom levels at the beginning of Burst 2, and Burst 3, compared to Burst 1, respectively. Regarding our control variables, we found increased ADHD symptom levels in children receiving ADHD medication, which overlaps with an ADHD diagnosis in our sample.Similarly, to test for the association of self-reported daytime sleepiness and ADHD symptoms at the same time, we likewise calculated a multilevel model . No effeSignificant effects were found for the random intercept and both random slopes, implying substantial variance in children’s initial ADHD symptom levels, variance in symptom level change within bursts, and variance in the size of the within-person association of ADHD symptom levels and daytime sleepiness.After conducting all planned and pre-registered analyses, we decided to investigate children’s ADHD symptom levels separately for symptoms of inattention and symptoms of hyperactivity-impulsivity. As we will argue in the discussion section, these core dimensions of ADHD might show a unique and discriminative link to markers of sleep quality in everyday life. To this end, we conducted two separate scores for children’s levels of inattention , and levels of hyperactive-impulsive behavior , and reran our analysis in correspondence to the procedure described above, however, with separate multilevel models for levels of inattention, and hyperactive-impulsive behavior. The complete results of these post-hoc analyses are added to the appendix . In summIn the current study, we investigated the relationship of self-reported sleep variables and ADHD symptoms on a between- as well as a within-person level in German schoolchildren. With an intensive longitudinal study, applying a measurement burst design with ambulatory assessment, daily fluctuations in the constructs of sleep quality, daytime sleepiness and ADHD symptom levels were assessed. With this measurement approach we expanded the current literature on sleep and ADHD. In contrast to earlier studies, which compared groups of children with and without ADHD diagnosis, we defined ADHD symptoms on a dimensional level by using a general population sample, in line with current dimensional theories for the classification of psychological disorders . FluctuaMultilevel analyses did not confirm a relationship between sleep quality during the night and ADHD symptoms on the subsequent day on the inter- or the intraindividual level. Accordingly, we must reject our first two hypotheses, since we had expected a negative effect of sleep quality on ADHD symptoms within and between children. Although this is to our knowledge the first study to investigate the relationship of sleep and ADHD symptoms in (school) children’s daily lives, theory and previous research would have hinted to such a connection. State regulation theory implies that with worse sleep , children have less capacity for self-regulation and therefore show more ADHD symptoms . SupportSimilarly, we did not find an interindividual effect of subjective daytime sleepiness on ADHD symptoms. However, on the within-person level, we found a negative association between daytime sleepiness and ADHD symptoms. Our data implies that in moments when children feel more tired and sleepy during the day, they report less ADHD symptoms than when they feel more activated and awake. This finding is contrary to our hypothesized effect. It seems that children who are well rested also experience more energy to feel restless. One possible explication for the effect could lie in the timely structure of the study. Sleepiness and ADHD symptoms were measured three times a day. As Especially interesting is the found effect of the three bursts on ADHD symptom levels. The findings indicate that in Burst 3 ADHD symptoms at the beginning of the burst are significantly lower than in Burst 1. In the second model, this effect can also be found for Burst 2, where children start lower than in Burst 1. The difference between the models results from the fact that in the first model only ADHD symptoms on the second moment at the middle of the day are considered. The second model uses all three indications of ADHD symptom levels on each day. Several possible explanations can be found for this effect of burst on ADHD symptom levels. The most obvious explanation might be an aging effect. Within the course of normal development, children get more attentive and learn to better self-regulate their behaviour. Therefore, symptoms of inattention and hyperactivity/impulsivity decrease with age ,39. AnotAnother result we found is the significant decrease of ADHD symptoms within each of the bursts. In general, children reported significantly less symptoms at the end of the burst than in the beginning. This could be explained by an initial-elevation bias . IndepenIn our original models, we integrated all three core symptoms of ADHD into one common factor to enhance the reliability of the scale. However, previous research has found that different ADHD subtypes might be associated with different sleeping patterns ,41. For These exploratory analyses incorporate some interesting insights into our data and the implications should be investigated more thoroughly in future research. To summarize, it seems that our hypotheses apply better for the inattentive factor of ADHD while hyperactivity/impulsivity seem not to be related to sleep and sleepiness as measured in our study, or even in the opposite direction than expected. These findings might reflect a general effect where sleep quality and sleepiness only affect attention. It might however also be an effect of the specific age group. People tend to grow calmer with age and are better able to self-regulate their behaviour with age. This effect has often been shown in ADHD research, where adults report less hyperactive/impulsive symptoms than children but still significant impairments in their attention . Thus, cDespite the numerous advantages the current study adds to the existing research literature, the study design also might incorporate specific drawbacks and potential for improvement.In general, ambulatory assessment has great potential to capture daily fluctuations in ADHD symptoms and sleep of children. However, there is still a lack of adequately tested scales to use within this specific research design . We trieAnother drawback of ambulatory assessment always is the high participant burden which is put on the participants. Answering the same questions three times a day for 18 days in three different bursts is very exhausting, especially for children. Although we shortened the scales as much as possible, occasions with missing answers increased with time within each burst and many children dropped out of the study between the bursts. We tried to control for these dropouts and missing data by including burst, day within burst and weekend into the models. With compliance rates of 48–58% we received enough data to model inter- and intraindividual differences of the children. Still, future research should try to prevent this dropout effect by reducing burden and enhancing commitment of the participants.Most obvious seems to be the question whether self-reports of sleep are a valid instrument to measure actual sleep quality in children. For measuring sleep, subjective and objective measurements all show their own advantages and drawbacks . The utiCritics might object that participants of this age might lack the relevant introspection and humans in general might not be able to give valid reports of their sleep, given that the key feature of sleep is the lack of consciousness . This liFurthermore, we decided to measure sleep quality by combining self-reported sleep onset latency and subjective sleep quality. These constructs have shown to be related to other psychological factors in earlier studies e.g.,  and depiAlthough the current study did not confirm the hypotheses, it might bring new ideas and questions to the research area. A very positive finding is the fact that children in our general population sample indicated overall relatively high sleep quality and low ADHD symptoms throughout their daily lives. Comparing different methods to evaluate sleep quality might help to define which measurement might be related to other physiological and psychological constructs. The finding that ADHD symptoms seem to decrease over time, both between and within the bursts should be further examined. The first might be investigated in future research by further examining developmental changes throughout the lifespan. For the second, the initial elevation bias should be integrated more into the planning and evaluations of ambulatory assessment studies.Since most items that were used in this project were originally developed for one-time assessment, an important goal for future research should be the development of well investigated questionnaires that can be used for daily measures, especially in self-report with children. These scales should prove to be valid, reliable, economic, minimally disruptive, not reactive, able to capture fluctuations in the daily experiences of participants, and ideally show accordance with objective measures . AmbulatEspecially interesting for future research might be the results from our exploratory analyses. As we found that most of our hypotheses would have been confirmed, had we only considered the inattention factor of ADHD symptoms, this discrimination of the core symptoms in research should be pursued further.In the current study we examined the association of sleep quality, daytime sleepiness, and ADHD symptoms in the daily life of German schoolchildren on an inter- and an intraindividual level. A significant negative intraindividual effect was found for daytime sleepiness on ADHD symptoms within participants, contrary to the hypotheses. Explorative analyses found significant effects of sleep and sleepiness on inattention on the inter- and the intraindividual level in the expected directions: Children who sleep better on average report less inattention; On days when children report better sleep, they indicate less inattention; And children who are sleepier on average during the day report more inattention. For hyperactivity/impulsivity we found an opposite effect to our expectations: in moments when children indicate to be sleepier during the day, they report less hyperactive/impulsive symptoms. We conclude that future research should preserve the advantages concerning ecological validity which the ambulatory assessment entails and possibly integrate it with the benefits that more objective measurements like actigraphy might add. Studies examining the precursors, correlations and effects of ADHD symptoms should split the construct in the two factors of attention and hyperactivity/impulsivity.


In low-income nations, low birth weight (LBW) is still a major public health concern, which accounts for 96.5 % of global LBW cases. Any newborn weighing less than 2500g is considered LBW, which is associated with a 20-fold increase in the chance of dying during infancy. Despite the severity of the problem, in Sub-Saharan Africa the high rates of LBW have not diminished in the recent decade. The goal of this study is to evaluate the prevalence of LBW and its risk factors in Angola, as there is a pressing need to address LBW and its substantial health and social implications.We used secondary data from the Angola Children’s Record Database of Demographic and Health Survey from 2015 to 2016. A binomial logistic regression model was used to investigate the prevalence of LBW and its related risk variables.From the 3738 children selected, 9.2% were born with LBW. The complete lack of formal maternal education , the absence of maternal iron supplementation during pregnancy  and women living in rural areas  were associated with LBW.Education appears to have a significant impact on LBW, emphasizing the importance of addressing literacy in Public Health policies. Lack of iron supplementation and rural residence can also be used as indicators of poor health-care access. Understanding the factors informs decision-makers and should pave the way for more targeted intervention and more efficient LBW policy.• Intervention in socioeconomic factors and health access during pregnancy might have a high impact on the LBW problem.• Addressing literacy as a major health determinant can guide a more efficient policy making and help stakeholders target their interventions.


ADHD patients often report that they are being flooded by sensory impressions. Studies investigating sensory processing show hypersensitivity for sensory inputs across the senses. While studying unimodal signal-processing is relevant and well-suited in a controlled laboratory environment, our daily interaction with our environment does not occur merely unimodal. A complex interplay of the senses is necessary to form a unified percept. In order to achieve this, the unimodal sensory modalities are bound together in a process called multisensory integration (MI).In the current study we investigate MI in an adult ADHD sample accompanied by resting-state functional magnetic resonance imaging (RS-fMRI).Twenty-five ADHD patients and twenty-four healthy controls were recruited. MI was examined using the McGurk effect, where - in case of successful MI - incongruent speech-like phonemes between visual and auditory modality are leading to a perception of a new phoneme. Mann-Whitney-U test was applied to assess statistical differences between groups. Resting-state functional MRI was acquired to realize a seed-to-voxel analysisMdn:5.83%, ControlsMdn:44.2%, U= 160.5, p=0.022, r=-0.34). When ADHD patients integrated phonemes, reaction times were significantly longer . Seeded medio temporal gyrus was negatively associated in functional connectivity to primary auditory cortex, inferior frontal gyrus, precentral gyrus, and fusiform gyrus.Susceptibility to MCGurk was significantly lowered for ADHD patients (ADHDMI seems to be deficient for ADHD patients for stimuli that need late attentional allocation. This finding is supported for higher functional connectivity from unimodal sensory areas to polymodal, MI convergence zones for complex stimuli.No significant relationships.


In efforts to explore adjunct/alternative treatments for ADHD, this studyinvestigated the associations between dimensions of physical activity (PA) andchildren’s ADHD symptoms and impairment. Current evidence-based treatmentsinclude medication and behaviour management, but there is widespread consensusthat more treatment options are desirable. Although there is increasing supportfor PA as an adjunct/alternative to existing treatment for ADHD, the interplayof specific dimensions of PA has not been studied. Fifty-one parents of childrenaged 6–12 years with ADHD filled out questionnaires. Hierarchical regressionanalysis indicated that only some dimensions of PA explained a statisticallysignificant portion of the variance in ADHD symptoms, beyond that explained bytypical demographic variables. PA dimensions did not account for a statisticallysignificant portion of ADHD impairment. Refining the measurement of how longchildren have engaged in PA is a key step in generating evidence for PA as anadjunct or alternate treatment for ADHD, and developing guidelines to manageparental expectations for this treatment in the benefit of their children. ADHD is alsonegatively associated with health-related quality of life scores, diet and sportsparticipation  is defined as a contrived skeletal movement associatedwith an increase in the use of energy . PA invoThree empirical arguments support the potential utility of PA in children with ADHD: (1)PA influences the same catecholaminergic systems as those targeted by stimulantmedications ; (2) PA Although most of these studies are correlational, some employ experimental designs andshow a reduction in ADHD symptoms from PA treatments . The maiThe purpose of the current study is to examine the interplay between intensity, frequencyand duration of physical activity (PA) and children’s ADHD symptoms and impairment,based on parent reports. Specifically, three hypotheses guided this study: (1) Parentalreports of children’s PA levels account for children’s ADHD symptoms and/or impairment,(2) Parental reports of children’s engagement in PA account for children’s PA levels and(3) Higher reported-levels of PA and/or PA engagement by parents are associated withlower levels of children’s ADHD symptoms and/or impairments. Investigating howintensity, frequency and duration of PA relate to ADHD symptoms and/or impairment isnecessary to evaluate how PA might help children with ADHD.M = 0.30, SD =0.46). A majority of guardians identified as Canadian, and most did not specifytheir ethnic identity. However, the sample represented a middle-to-slightlyhigher socio-economic bracket as the median reported income was between $100,000and 149,999. The median income in the jurisdiction of the study is approximately$100,000. Guardians were sought for two reasons. First, collecting data fromguardians allowed the authors to employ an online survey format. Second,collecting data from guardians allowed the authors to evaluate the feasibilityof the format for future research especially critical now given reductions within-person access during COVID-19. Participating guardians were required to have:(1) at least one child within the ages of 6–12 years with a primary DSM-IVand/or DSM-5 diagnosis of ADHD, (2) lived with the child for at least the pastyear, (3) served as legal guardians and (4) fluency in English. Participatingguardians were emailed a consent form and password to securely access thefollowing four online questionnaires administered using a password-protectedGoogle Form: (1) the ADHD Rating Scale-IV  from a largemetropolitan city were invited to report on their children’s ADHD, PA andengagement in PA. A majority of guardians were female and 70% of children onwhich they reported were male , their perception of their child’s enjoyment of PA(Enjoyment) and their efforts in engaging their child in PA(Engagement) using a 5-point Likert-type scale ranging from“Extremely” to “Not at all.” No psychometricanalyses were conducted on the PAQ because guardians did not complete the samenumber of ratings due to differences in number of PAs reported. Thus, internalconsistency could not be computed due to missing cases, and test–retest wasimpractical given the cross-sectional nature of the study.3. The PAQ was designed by the first author to help guardians report on children’s PA. Thefir4. The CFIQ is a two-part questionnaire with a total of 38 questions designed toassess the child (Part I) and the guardian’s (Part II) demographic characteristics,mental health issues and treatment or intervention information . Importaf = 0.35, and threepredictors . Given theseparameters, a minimum total sample size of 36 was required. Although previousstudies have yielded small to medium effects of PA on children with ADHD andautism spectrum disorders . Also, two dimensions of reported PA levels (i.e. intensity and duration)were significantly correlated . Given the high correlation in these two PAdimensions and to avoid multicollinearity in subsequent regression analyses,these dimensions were transformed into Z variables and combined to form anaggregate PA variable (i.e. PA Aggregate). PA Aggregate was significantlyassociated with ADHD RS but not IRS . All PAengagement questions  werealso highly correlated, so they were transformed into Z variables, andaggregated into a single variable (Engagement Aggregate) to avoidmulticollinearity. Engagement Aggregate was significantly correlated with PAAggregate  but not ADHD RSor IRS.All analyses were conducted with IBM SPSS Statistics (Version 27 for Mac). age of diagnosis andage when symptoms were first noticed in the first layer ofpredictor variables. PA Aggregate was included in the second layer ofpredictors. The second regression  effectiveness inthe first layer of predictors. Although PA Aggregate was not significantlycorrelated with IRS as shown in Two hierarchical linear regressions were conducted based on the statisticallysignificant correlations observed in gression  includeddid not approach significance in its association withADHD symptoms and/or impairment. This result suggests that children’s exertion in PAas measured by intensity and duration matters more than the frequency of theirparticipation in PA. That is, a child who engages in PA frequently but does not movemuch may not reap the effects of PA as expected. Nonetheless, engaging in PAfrequently is the first step to learning to exert intensity and doing so forextended amounts of time.The current study was designed to examine the relationship between PA levels, PAengagement and children’s ADHD symptoms and/or impairment based on parent reports.Amongst the three PA dimensions evaluated in the study, frequency was the onlyvariable that Our findings are congruent with a meta-analysis of 79 studies conducted by Chang andcolleagues  on theenotrelated to ADHD symptoms or impairment. The lack of correlation could be attributedto how engagement was measured. There is potential measurement error in havingparents report on a child’s internal volitional state. Nonetheless, a positiveassociation between PA engagement and PA levels was found, suggesting that parentsreported higher levels of engagement in PA when children participated in moreintense and longer durations of PA. These findings are congruent with previousfindings  of eachPA. A negative association between ADHD symptoms and PA could havebeen missed due to this narrow time span.In terms of accounting for variance in ADHD symptoms and/or impairment, the firsthierarchical regression showed that aggregating PA intensity and duration explaineda statistically significant portion of the variance in ADHD symptoms, beyond thatexplained by typical demographic variables . Asanticipated, the coefficient for age of initial symptoms was negative at −.33indicating that earlier diagnosis is associated with worse ADHD symptoms.Surprisingly, the coefficient for PA aggregate was positive at +.31. At first glancethis finding appears to be the exact opposite of what one would expect to find if PAwas indeed helping children. However, this positive relationship could be revelatoryof how PA serves as an outlet for children who experience significant hyperactivity;for example, children who experience more hyperactivity may find it necessary toengage in did notaccount for a statistically significant portion of the variance in ADHD impairmentbeyond that accounted by other typical variables (e.g. other treatments andperceived BPT effectiveness). However, the coefficient of .11 was positive as in thefirst regression. Again, this positive coefficient could be interpreted to suggestthat children who experience the most impairment use PA as an outlet. Alternatively,it is possible that our measurement failed to capture the longer-term trend.Notwithstanding, the nonsignificant relationship between PA aggregate and ADHDimpairment, a positive coefficient of .44 was found between the use of othertreatments and ADHD impairment. This positive association suggests that childrenwith more impairment are involved in more treatments to lower impairments. PerceivedBPT effectiveness, however, was associated with lower ADHD impairment as expected.The coefficient of −.37 indicates that when BPT effectiveness is rated as low, ADHDimpairment is viewed as higher. Future research needs to include questions about thelength of time of all treatments so as to account for the window of time for effortsto reduce ADHD symptoms and impairments.The second hierarchical regression showed that PA aggregate This study has several limitations. First, the PAQ was newly designed as a meansto measure parental reports of PA intensity, frequency, duration and PAengagement in their children. The PAQ was created because to the author’sknowledge, there are no existing parental reports of physical activityquestionnaires in the literature that captures different dimensions of PA inchildren. Although the freely available International Physical ActivityQuestionnaire  could haMethod section. Futurework should consider modifying the PAQ  so that it can become a measure that permitsinternal consistency analyses to be done. Moreover, as noted in the previoussection, the PAQ should also be revised to include questions about thespecific length of time for each PA reported. Askingparents to simply list their children’s PAs within the last 6 months lowers thesensitivity of the measurement tool for capturing the most accurate associationbetween an intervention and its effects.While the PAQ we developed was based on previous measurement of physical activityused in the literature, its validity and reliability has not yet beenestablished for reasons mentioned in the Second, the sample size was relatively small. Thus, the current study could havebeen under powered, risking the detection of a significant association betweenPA and ADHD impairment (measured with the IRS in the present study). Largersamples are needed to help clarify the relationship between PA and ADHD symptomsand impairment. Moreover, future studies need to ascertain the ethnicidentification of the sample.parent by proxy problem which suggeststhat parental ratings are not interchangeable with a child’s ratings ofactivities (Third, the study relied on guardians’ self-reports of their children’s ADHD andPA. Although self-reports, in the form or questionnaires, are the most commonand feasible method of measuring PA at the population level ,the ristivities . Indeed,Fourth, while Visser and colleagues  contend Fifth, given the scope of the original study, children’s social and emotionalfunctioning was not explicitly measured. However, assessing children’s level ofsocial and emotional wellness is necessary for future work. Children who haveADHD are at risk for anxiety and depression, and PA may indeed be associatedwith alleviating these states. This would add yet another dimension to arationale for including PA as a supplemental treatment for children withADHD.Figuring out how to properly measure the relationship between PA and ADHD may bethe first step towards understanding how PA is associated with ADHD and howguidelines can be accurately developed for children with ADHD. At present, thisstudy highlights the positive association between children’s physical activityand ADHD symptoms. Although the results of this study have provided some answersto the research questions posed, perhaps the overarching conclusion is that weneed better measurement tools to evaluate PA in children with ADHD. For example,we have no clarity on what the optimal levels of PA are to potentially maximizethe benefits of PA for those children with varying levels of ADHD.PA continues to be a variable worthy of study. It represents a potentiallylow-cost alternative but its long-term effects in relation to currentevidence-based treatment options are lacking . Sanchez