Secale cereale L.) is a cereal that is closely related to wheat, and it is an important crop in Central, Eastern and Northern Europe. The aim of the study was (i) to identify diverse groups of rye accessions based on high-density, genome-wide analysis of genetic diversity within a set of 478 rye accessions, covering a full spectrum of diversity within the genus, from wild accessions to inbred lines used in hybrid breeding, and (ii) to identify selective sweeps in the established groups of cultivated rye germplasm and putative candidate genes targeted by selection.During domestication and subsequent improvement plants were subjected to intensive positive selection for desirable traits. Identification of selection targets is important with respect to the future targeted broadening of diversity in breeding programmes. Rye , plant fertility and reproduction , and plant growth and biomass production.Population structure and genetic diversity analyses based on high-quality SNP (DArTseq) markers revealed the presence of three complexes in the Our study provides valuable information for efficient management of rye germplasm collections, which can help to ensure proper safeguarding of their genetic potential and provides numerous novel candidate genes targeted by selection in cultivated rye for further functional characterisation and allelic diversity studies.The online version contains supplementary material available at 10.1186/s12870-023-04337-1. Q (controlling inflorescence structure in wheat), teosinte branched1 , Shattering1 , Btr1 and Btr2 (required for the disarticulation of rachis) [Y1 gene, related to high carotenoids levels and yellow kernels [Rht gene, controlling reduced height, and rice Hd1, controlling flowering time [During domestication and subsequent diversification and improvement plants were subjected to intensive positive selection. Consequently, several key traits differentiate crop plant from their wild progenitors. In the case of cereal crops, these traits include: larger grain size, loss of natural seed dispersal mechanisms (causing seed retention until harvest), changes in the plant’s architecture , and in plant physiology  , 2. A nu rachis) , 4. Dive kernels , wheat Ring time –7.At first, the QTL approach was predominately used to identify domestication/improvement loci –10. MoreEarly studies suggested that several, large effect loci underlie the phenotypic switch from a wild progenitor to a domesticate. More recently, studies based on genome-wide SNPs revealed hundreds of loci showing signatures of selection , 15, 16,Secale cereale L.) is a cereal closely related to wheat, and an important crop in Central, Eastern and Northern Europe. It is mainly used for the production of flour for bread making, as animal feed, and in distilleries to produce whiskey and vodka. Rye has the highest tolerance of abiotic and biotic stresses  among the small grain temperate cereals and is a widely used source of genetic variation for wheat improvement [Rye  is poorly know, and was at a point of time erroneously described as S. vavilovii and sent to several germplasm collection under this description causing confusion, with some researches working on the ‘true’ S. vavilovii, and others on S. iranicum, only mistakenly described as S. vavilovii. Thus, the matter of Secale classification is not fully resolved yet.According to Germplasm Resource Information Network (GRIN), there are four species recognized in the fication –26. A poy et al. , who proS. cereale subsp. cereale). Both S. vavilovii and S. strictum, among others, had been suggested as likely candidates [Rye domestication happened approximately four thousand years ago , 28, mucndidates . Centralndidates . Recent ndidates , 32–35. ndidates , 36–38.The aim of this study was to: i) assess the genetic diversity structure in a diverse collection of 478 rye accessions representing different geographic origins and improvement status based on genome-wide, high-quality GBS markers, ii) identify selective sweeps in established germplasm clusters and iii) indicate potential candidate genes targeted by selection in rye.In total 79 877 SNP markers Dataset-1) differentiating 478 rye accessions , and 14 accessions described as unknown in genebank records. Five S. s. subsp. strictum and three S. s. subsp. anatolicum accessions were also assigned to population 1—ca. 24% and 38% of accessions representing these taxa included in the study, respectively. Population 2 included all ten S. sylvestre accessions and accessions representing S. strictum subspecies: most of S. s. ssp. kuprijanovii accessions  and also accessions of S. s. ssp. strictum  and S. s. ssp. anatolicum . The remaining three S. s. ssp. kuprijanovii accessions were classified as admixtures, together with seven S. s. ssp. strictum, two S. s. subsp. anatolicum, and two S. s. subsp. africanum accessions.Our analysis showed that K = 2 explained best the population structure Figure S. PopulatS. sylvestre accession and one S. s. subsp. strictum accession) were assigned to subpopulation p2_a and the remaining 37 accessions (36 accessions of S. strictum subsp. and one S. c. subsp. dighoricum accession) were assigned to subpopulation p2_b. The second additional STRUCTURE analysis was run on 430 accessions classified initially as population 1. At Q ≥ 0.7 as many as 229 accessions were classified as admixtures, 192 accessions were assigned to subpopulation p1_a, and 9 accessions were assigned to subpopulation p1_b. We found the result of STRUCTURE analysis of subpopulation 1 not conclusive and analysed the genetic structure of the whole set further using PCoA and NJ clustering. The results of both additional STRUCTURE runs are shown in Figure SWe further performed two additional STRUCTURE analyses for the germplasm groups indicated in the initial STRUCTURE analysis. In both cases K = 2 was indicated as the most probable value explaining population structure in these subsets Figure S. The firS. sylvestre accessions and a group containing S. strictum accessions. These groups corresponded, respectively, to subpopulations 2_a and 2_b identified in additional STRUCTURE runs. The third group indicated by PCoA, occupying a relatively small area of diversity space, corresponded to population 1 indicated by STRUCTURE. As expected, landraces were dispersed across a larger plot area than modern and historical cultivars, and thus turned out to be more diverse.PCoA and STRUCTURE results were in a very good agreement. PCoA clustered the accessions into three groups Fig. . AccessiThree major clusters could be distinguished in the NJ tree showing phylogenetic relationships between accessions: A1, A2, and A3 Fig. . AccessiS. sylvestre accessions, and cluster A2 contained predominantly S. strictum accessions, specifically all S. strictum subsp. kuprijanovii analysed. Cluster A3 contained all cultivated rye S. cereale subsp. cereale and S. vavilovii accessions and almost all wild/weedy S. cereale accessions. Wild/weedy S. cereale accessions and S. vavilovii accessions were dispersed in all A3 subclusters, with exception of subcluster A3.4.Clustering corresponded largely with the taxonomy, too Fig. B. The moS. cereale subsp. cereale influenced the clustering  and were dispersed in subclusters A3.1, A3.2 and A3.3, similarly to the accessions from NSGC , while accessions from NordGen were absent from cluster A3.1. Taken together the accessions obtained for the study provided a good representation of diversity within the Secale genus.The highest numbers of accessions for this study were obtained from the following four genebanks: IPK 113), NSGC 97), NordGen (56), and PAS BG (52). Accessions obtained from the IPK genebank covered a broad spectrum of diversity within S, NordGen13, NSGC ST = 0.468, 53% percent of total molecular variance attributed to variation within populations, P < 0.001). A very high degree of differentiation was also found for the three accessions groups indicated by PCoA and NJ clustering , with the proportion of molecular variance explained by the differences among populations equal 55% and pairwise population FST values ranging from 0.428 between accessions groups A2 and A3 to 0.734 between accession groups A1 and A3 (P < 0.001). AMOVA analysis of the six germplasm groups defined based on NJ clustering: A1, A2, A3.1, A3.2, A3.3, and A3.4 attributed 31% of the total molecular variance to the differences among populations and 69% to the differences within populations. There was a very high degree of differentiation between groups A1 and A2 and the remaining germplasm groups  to 0.603 (between A1 and A2). For the pairwise comparisons involving A2 the FST values ranged from 0.603 (between A2 and A1) to 0.318 (between A1 and A3.4b). In the remaining germplasm group pairs the degree of differentiation was moderate – pairwise FST values ranged from 0.054 (between groups A3.1 and A3.2) to 0.205 (between groups A3.2 and A3.4). The only exception was the population pair A3.1 and A3.3, where the differentiation was low – pairwise FST = 0.035  between the two groups of lines from hybrid breeding program (A3.4a and A3.4b).A very high degree of differentiation was found between the two subpopulations indicated by STRUCTURE (FS. strictum group to only 803 markers (7.6%) in the S. sylvestre group. A similar pattern of the chromosomal distribution of SNPs could be observed in most germplasm groups, with the highest proportion of SNPs on chromosomes 2R and 5R and the lowest on chromosomes 1R, 4R and 6R  and Ho (observed heterozygosity) values, and physical map length by germplasm group is given in Table S. vavilovii (Table S. vavilovii (0.463). The lowest Ho values, in the range 0.145–0.033, occurred in the germplasm groups containing inbred lines from hybrid breeding program. A low Ho value of 0.183 was obtained for the group of S. sylvestre.He and Ho values were 0.211 and 0.228 for the whole set. Within established germplasm groups He ranged from 0.196 for the A1 group established based on NJ clustering to 0.333 for the taxonomic group S (proportion of polymorphic sites), ϴ (theta), π (nucleotide diversity), and Tajima D’s values computed for the whole set of 478 accessions and for the established germplasm groups are given in Table SS. strictum and the lowest in S. sylvestre. Average Tajima’s D values were negative in each germplasm group indicating the occurrence of positive selection. The weakest negative Tajima’s D values were recorded in breeding lines, suggesting weak selection in this group. In the cultivated germplasm the strongest negative Tajima’s D value was obtained for modern cultivars, followed by historic cultivars, implying a strong selection in this groups. Among taxonomic groups, the strongest negative Tajima’s D value was noted for S. vavilovii.Values of the diversity indices PST indicating moderate differentiation between these clusters. Thus, our selection inference is based on the following groups of cultivated accessions: g1 , g2 (divergent Turkish landraces from cluster A3.1), g3 (diverse landraces from cluster A3.3), and g4 (inbred lines from hybrid breeding program from cluster A3.4). Selective sweeps detection was also performed separately for groups g4a (inbred lines from Carsten heterotic pool) and g4b (inbred lines from Petkus heterotic pool). The information on accessions’ membership in the sweep detection groups is given in Table SNJ analysis revealed the presence of genetics clusters in cultivated rye germplasm and this result was supported by the pairwise FIn total, for all the sweep detection groups, 170 putative candidate genes were found in the Lo7 genome in the vicinity of the outlier positions within the identified sweeps (Table SGene ontology (GO) enrichment analysis, performed on the identified putative candidate genes, revealed that 34 GO terms were significantly overrepresented Table S, includiBased on the literature we compiled a list of ten cereal domestication/improvement genes and using BLAST  determinThe first aim of this study was a detailed analysis of genetic diversity and genetic structure in a broad collection of diverse rye germplasm and the identification of germplasm groups suitable for detection of selective sweeps. Several studies on rye genetic diversity were carried out to date, using SSR, array-based (DArT), GBS, and, recently, whole genome resequencing data , 40, 41.For the detection of SNP variation, the DArTseq genotyping-by-sequencing method was used. This method was previously shown to efficiently target low copy regions of the very large – ca. 8 Gb , and higS. cereale subsp. cereale) accessions  accessions. Only one S. cereale accession  was assigned to population 2, together with S. sylvestre and S. strictum accessions. We suspect, that this accession was misclassified or mislabelled during ex situ conservation. A verification of this hypothesis would require phenotypical evaluation, since in the genebank records there is no additional information available.STRUCTURE analysis suggested the presence of two subpopulation in the analysed collection (K = 2), dividing the set in to two groups—the first consisting of Secale genus – three main complexes corresponding to the taxonomy: the most divergent S. sylvestre complex, the S. strictum complex, and the S. vavilovii/S. cereale complex. This outcome agrees largely with results of previous studies on rye genetic diversity [ST values, indicating a very high degree of differentiation between these three germplasm groups.Previous studies had shown, that the implementation of Delta K method often indicates K = 2 (suggesting the presence of two subpopulations) as the highest level of hierarchical structure within the analysed germplasm set, even if the structure is more complex. Hence, the use of other methods in conjunction with Delta K is recommended –51. Theriversity , 24, 26,S. strictum subsp. samples included in the study  allowed us to gather novel information concerning its genetic diversity. We revealed a considerable genetic diversity of this genus, as demonstrated by high values of genetic diversity indices and the results of STRUCTURE analysis, with its representatives present in both populations indicated and also classified as admixtures. NJ clustering indicated differences between S. strictum subspecies analysed. S. strictum subsp. kuprijanovii (14 accessions) turned out to be the most homogenous group among S. strictum subspecies and were located exclusively in cluster A2. Accessions of S. strictum subsp. anatolicum and S. strictum subsp. strictum  occurred in three clusters of the NJ tree: in cluster A2 (together with S. strictum subsp. kuprijanovii), and also in clusters A3.1 and A3.2. In clusters A3.1 and A3.2 S. strictum subsp. anatolicum and S. strictum subsp. strictum accessions were intermixed with cultivated and weedy accessions of Secale cereale. However, it cannot be excluded that some of this S. strictum samples placed within S. cereale complex are only erroneously described as S. strictum, since a morphological description was not performed within this study. We find that evaluation of morphological characters would be advisable as a part of future molecular studies on rye taxonomy and phylogeny to exclude possible misclassification of some accessions. On the other hand, the diversity of ten S. sylvestre accessions analysed in this study turned out to be very small, indicating a need for a follow-up, more detailed examination, to ensure proper safeguarding of the genetic potential of this wild relative of cultivated rye. In consistence with the earlier molecular reports examining taxonomic relationships within the genus Secale [S. vavilovii accessions analysed were intermixed with the S. cereale accessions in clusters A3.1, A3.2 and A3.3 of the NJ tree. Referring to the explanation of Zohary et al. [S. vavilovii, this result would suggest that the samples analysed in this study were “true” S. vavilovii forms. Surprisingly, we observed a strong negative Tajima’s D value in this germplasm group which could be a result of an unintentional selection during genebank conservation. Such selection is possible and could be caused by a low germination rate during regeneration. A coanalysis with S. vavilovii samples from a recent collection would be needed to verify this hypothesis. Based on the analysis of our large germplasm set, comprising 58 wild/weedy Secale cereale accessions  we were able to confirm the lack of separation between weedy and cultivated forms of Secale cereale, indicated by earlier studies [A large number of s Secale , 26, 40,y et al.  on the c studies , 26, 40 ST value, was moderate. Further, the remaining cultivated accessions formed three major clusters: one containing the majority of cultivars and related landraces, and two clusters comprising mostly rye landraces. Thus, the study confirmed the indication from earlier works [We detected the presence of genetic clusters within cultivated ryes and the influence of improvement status on the clustering. NJ clustering indicated a genetic distinctiveness of inbreds used in rye hybrid breeding from the remaining cultivated rye accessions, with the two heterotic pools forming separate clusters in the NJ tree. However, the degree of genetic differentiation between heterotic pools, measured by Fer works , 32, 33,er works , 52. Theer works , 30. TheST outlier approach and the XTX statistic in pairwise comparisons between three germplasm groups. The germplasm groups used consisted of 46 individuals representing rye genetic resources, 38 inbred lines used in rye hybrid breeding, representing the seed parent pool, and 46 inbred lines representing the pollen parent pool. The analyses were done based on genotypic data obtained with the use of Rye600k array. In each comparison numerous outlier markers were identified, which clustered in a few distinct genome regions, and in total 27 putative selection targets – rye orthologues of cloned and functionally characterised rice genes – were found in these regions. Functions of these putative orthologues were related, among others, to plant height, grain size and number, pollen germination ability, other plant development and morphology functions, abiotic and biotic stress, and regulation of various physiological processes. Subsequently, Li et al. [S. vavilovii accessions and three selective sweep detection methods (reduction of diversity (ROD), genome-wide scan of fixation index (FST) and cross-population composite likelihood ratio (CP-CLR)) were used. As a result, 11 selective sweeps with the total of three candidate rye genes, related to brassinosteroid signalling, the transition from vegetative to floral development, and also to tillering and grain yield regulation, were detected in common by the three approaches. The number of candidate genes detected by at least one tool ranged from 10 to 21. Recently, based on resequencing data, Sun et al. [ST, XP CLR and ROD approaches on cultivated and weedy ryes from a worldwide set of 116 accessions. As a result selective sweeps with 279 candidate genes were identified by at least two methods and included genes related to plant height, disease resistance, tiller number and grain yield, and also genes with shattering-related functions.Detection of selection targets was attempted in rye for the first time by Bauer et al. , who usei et al.  identifii et al. . Specifin et al.  performeS. cereale complex. To reduce the length of the manuscript and to focus on the most probable selection targets, we reported only the sweeps that were identified in common by the three algorithms used and listed the potential candidate genes located in the vicinity of the detected outliers.In this study, we used a different approach to detect genome regions targeted by positive selection in rye. Each of the defined rye germplasm groups was analysed separately with three algorithms detecting various distinct signatures of selective pressure: SweeD , OmegaPlGenome-wide studies on the influence of selection on the crop plant genome demonstrated that numerous loci, scattered across the genome, are targeted by selection pressure , 15. In We were not able to find a clear correspondence between positions of outliers located in this study and the location of known cereal domestication genes orthologs in the rye genome. However, this result is not altogether surprising since the methods used in this study are dedicated to detection of recent and strong positive selection . The oveCandidate genes under selection identified so far in crop plants often represent functions related to response to environmental stimuli, such as biotic and abiotic stress resistance, plant architecture, seed size and composition , 57, 58.Restorer of Fertility (Rf) genes are members of this family [To identify the key candidate genes we used the values of the statistics computed by the algorithms SweeD, OmegaPlus and RAiSD, and we also performed GO term enrichment analysis. One of the significantly enriched GO terms was phosphorelay signal transduction system, which is involved in turning on and off cellular responses to environmental stimuli , 62, sucs family . TIR-NBSs family .Key targets in rye breeding are disease resistance, resilience to drought and heat stress, and yield improvement . Also, bSecale genus: S. sylvestre, S. strictum and S. cereale/vavilovii. We revealed a relatively narrow diversity of S. sylvestre, very high diversity of S. strictum, and signatures of strong positive selection in S. vavilovii. Within cultivated ryes we detected the presence of genetic clusters and the influence of improvement status on the clustering. Rye landraces represent a reservoir of variation for breeding, since a large portion of their diversity is not represented in rye cultivars, and especially a distinct group of landraces from Turkey should be of special interest as a source of untapped variation. Using three sweep detection algorithms we found that signatures of selection are dispersed in the rye genome and identified 170 putative candidate genes targeted by selection in cultivated rye related, among others, to response to various environmental stimuli , plant fertility and reproduction , plant growth and biomass production. Our study provides useful information for efficient management of rye germplasm collections, that can help to ensure proper safeguarding of their genetic potential and provides numerous novel candidate genes targeted by selection in cultivated rye for further functional characterisation and allelic diversity studies.Based on a genome-wide detailed analysis of genetic diversity structure in a broad collection of diverse rye germplasm, we identified three complexes within the Secale sp.) accessions representing different geographic origins and improvement status, belonging to 17 taxonomic units were analysed: 134 wild or weedy accessions, 161 landraces, 75 historic cultivars, 36 modern cultivars, 58 breeding lines and 14 accessions of an unknown improvement status. The germplasm collection used was composed of three sets: (i) germplasm set 1 consisted of 340 accessions obtained as seed samples from several genebanks and breeding companies, (ii) germplasm set 2 consisted of 54 rye inbred lines representing heterotic pools used in rye hybrid breeding at HYBRO Saatzucht [Secale. The accessions from germplasm set 3 were obtained from eight genebanks and consisted of 15 landraces and 69 wild/weedy accessions representing 13 taxa. Further details can be found in [In total 478 rye  as described in [For accessions from germplasm set 1, tissue was collected and DNA isolated as described in . Informaribed in . For selribed in . LD filtribed in .The number of clusters (K) capturing the major structure in data was identified with STRUCTURE 2.3.4 software  using thP-value criterion of < 0.01.Three algorithms: i) SweeD , ii) OmeAdditional file 1: Figure S1. Summary of information on 12 846 HQ SNPs polymorphic in 478 diverse rye accessions. A. Histogram of polymorphic information content (PIC) values. B. Histogram of minor allele frequency (MAF) values. Figure S2. Plot of Delta K values for number of assumed subpopulations (K) ranging from 2 to 14. Figure S3. Population structure of 478 rye accessions at K=2 based on 12 846 SNPs. Each accessions is represented by a vertical stripe partitioned into coloured segments with lengths representing the membership fractions in the inferred clusters. The order of accessions in the plot is the same as in the Table SFigure S4. Plot of Delta K values for number of assumed subpopulations (K) ranging from 2 to 14. A. Plot based on STRUCTURE analysis of 48 accessions classified as population 2 and admixtures. B. Plot based on STRUCTURE analysis of 430 accessions classified as population 1. Figure S5. Population structure of rye accessions at K=2. Each accessions is represented by a vertical stripe partitioned into coloured segments with lengths representing the membership fractions in the inferred clusters. The order of accessions in the plot is indicated in the Table SFigure S6. Principal Coordinates Analysis plot showing relationships between 478 rye accessions genotyped with 12846 SNPs with accessions labelled according to the outcome of NJ clustering. Figure S7. Neighbor-joining tree based on 12 846 SNP markers showing relationships between 478 rye accessions with accession labelled according to source. Figure S8. Chromosomal distribution of polymorphic SNPs by germplasm group. A. Accessions grouped according to improvement status. B. Accessions grouped according to taxonomy. C. Accessions grouped according to the outcome of NJ clustering. D. Accessions grouped according to their membership in sweep detection sets. Figure S9. Neighbor-joining tree based on 12 846 SNP markers showing relationships between 478 rye accessions with branch colour indicating cultivated rye accessions belonging to the respective sweep detection set.Additional file 2: Table S1. Information on rye accessions used in the study, including genebank accession number, name, source, taxon, improvement status, country of origin, geographic region, group memberships based on STRUCTURE anaysis and NJ clustering, and sweep detection set membership. Table S2. List of 12486 HQ DArTseq markers used in this study, including their sequences and position in the Lo7 reference genome. Table S3. Chromosomal distribution of SNPs by germplasm group. Table S4. Pairwise population FST values for accessions groups based on NJ clustering. Table S5. Values of genetic diversity indices for the collection of 478 rye accessions and each established germplasm group. Table S6. Information on common outliers and sweeps detected by all three methods  in groups of cultivated rye accessions. Table S7. List of putative candidate genes targeted by selection in cultivated rye. Table S8. Enriched GO terms for putative candidate genes from the selective sweep regions. Table S9. Literature based list of known cereal domestication/improvement genes and locations of their putative homologues in the Lo7 genome.


After qualitative analysis, four studies indicated no improvement in any of the ADHD symptoms compared with placebo. One study showed improvement in ADHD symptoms based on 1 of 5 scales applied. One study indicated significant improvement in general symptoms, inattention, and hyperactivity. One study indicated improvement in sustained attention but a worsening of impulsivity. In contrast, when using a quantitative analysis of the general symptoms of ADHD, the data showed no significant difference when comparing placebo with caffeine . (4) Conclusion: overall, the totality of the evidence suggests no significant benefit of caffeine over placebo in the treatment of children with ADHD.(1) Background: Attention-deficit/hyperactivity disorder (ADHD) is typically treated with stimulant medications, which may lead to several adverse effects. Recent animal studies have shown that caffeine can improve the symptoms of ADHD. This systematic review and meta-analysis sought to evaluate the effect of caffeine on ADHD symptoms in children. (2) Methods: PubMed, Embase, and Cochrane databases were searched for randomized controlled trials comparing caffeine with placebo in children, comparing overall symptoms of ADHD, inattention, hyperactivity, and impulsivity. (3) Results: We included seven RCTs in the systematic review for qualitative assessment, with 104 patients aged 5 to 15 years. Four of these studies ( Attention-deficit/hyperactivity disorder (ADHD) is a globally prevalent neurodevelopmental condition, affecting 5.3% of children , with boThe symptomatology of this disorder varies . On the The diagnosis can be made using the criteria outlined in the DSM-5 by the American Psychiatric Association . In chilPatients with ADHD have catecholaminergic dysregulation, mainly in dopamine and noradrenaline functions . The dopRecent studies have shown that medication for ADHD treatment can reduce the risk of accidents and unintentional injuries in children, adolescents, and adults with ADHD . NeglectPharmacological treatment is the first choice for children above 5 years old with ADHD ,17,18,19Pharmacologically, methylphenidate acts on the dopamine and norepinephrine transporters, inhibiting the reuptake of these substances in the terminal neuron of the synaptic cleft and thus increasing their availability for synapses . With moLisdexamfetamine also increases the release of dopamine and norepinephrine in neuronal synapses . HoweverWhen it comes to non-stimulant medications, atomoxetine selectively inhibits the reuptake of norepinephrine in neurons, increasing its availability in the synapse . ConsequGuanfacine and clonidine, on the other hand, act on the α2 adrenergic receptors present in neuronal cells . HoweverFurthermore, modafinil is a stimulant that inhibits dopamine reuptake by binding to the dopamine transporter and, in the cortex, also inhibits norepinephrine reuptake . AlthougIn addition, antidepressants such as bupropion and certain tricyclics can also be used as off-label treatments for ADHD when first- or second-line medications are ineffective or produce intolerable side effects . SimilarIn general, these important side effects may be intolerable for some patients , leadingThese characteristics, similar to those of first-choice medication for managing ADHD, raise the hypothesis that caffeine also plays a role in reducing impulsivity, improving sustained attention, and reducing hyperactivity. Recent literature reviews ,47,48 inThe systematic review and meta-analysis were conducted and reported in accordance with the guidelines outlined in the Cochrane Collaboration Handbook for Systematic Review of Interventions and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Statement ,50. The The inclusion criteria were: (I) randomized placebo-controlled clinical trials; (II) patients with an established diagnosis of ADHD; (III) intervention involving oral administration of caffeine; (IV) clinical assessment with a scale, checklist, or test measuring any ADHD symptom; (V) age group 5 to 17 years old; and (VI) published in English. Non-randomized comparisons and studies without a placebo control group were excluded. Studies that met inclusion criteria but did not report quantitative outcomes were included only in the systematic review and not in the meta-analysis.The search was conducted on 1 December 2022, in the following databases: PubMed, Embase, and Cochrane Library, without any restrictions on publication date, using the following search strategy: [ADHD OR “Attention Deficit Hyperactivity Disorder” OR hyperactivity] AND [Caffeine OR “energy drink” OR coffee] AND [child OR children OR pediatric]. After removing duplicates, two independent reviewers (G.P. and M.M.G.M.) examined the title and abstract of each study identified in our search strategy. They applied the pre-established inclusion and exclusion criteria. Subsequently, the same procedure was employed in the evaluation of the full text of eligible studies. Discrepancies between reviewers were resolved by discussion until a consensus was reached. The literature search strategy is summarized in Two independent reviewers  extracted the following data: (I) author and year; (II) study design; (III) number of patients; (IV) mean age of study participants; (V) caffeine dose; and (VI) time duration of caffeine administration; (VII) objective tests and checklists applied to measure the outcome. These include the ADHD symptom scales “Conners Rating Scale” (C.R.S.) and “Davids’ Hyperkinetic Rating Scale” (D.H.R.S.); and (VIII) the endpoints for each study.The “Davids’ Hyperkinetic Rating Scale” (D.H.R.S.) is a tool that was developed to evaluate and aid in the identification and measurement of the symptoms related to attention deficit hyperactivity disorder (ADHD) . This scThe “Corners Ratting Scale” (C.R.S.) is also widely used to assess ADHD and other behavior issues in children and adolescents . This meThe risk of bias evaluation was conducted independently by two authors (G.P. and M.M.G.M.) using the revised Cochrane Risk of Bias 2 tool (RoB-2)  for the In addition, for assessing the risk of bias in crossover studies, a set of criteria applied to randomized clinical trials was used in this analysis. This approach takes into consideration the potential biases related to treatment allocation, adequate blinding of participants and assessors, as well as appropriate analysis and reporting of results. Disagreements were resolved by consensus between the authors.2 statistics. Pooled analyses were performed with a random effects model, as per recommendations from the Cochrane Collaboration [We compared treatment effects on the continuous outcome of overall symptoms using Standardized Mean Difference (SMD) with a 95% confidence interval. If the same ADHD outcome was evaluated by more than one person , we combined the mean and standard deviation following the formula described in the Cochrane Handbook of Systematic Reviews of Interventions version 6.3 . Heterogboration . Statistn = 76) presented quantitative comparisons between the caffeine x placebo groups and were thus eligible for the meta-analysis.A total of 344 articles were found using the proposed search strategy. After the removal of duplicate records and ineligible studies, 12 studies remained and were fully reviewed based on the inclusion and exclusion criteria. Of these, a total of seven studies met all the inclusion criteria and were selected for the systematic review. Of these, four studies  [p = 0.45; I2 = 0%)  ,54,57,59I2 = 0%) .Five studies ,58,59,60Only three studies ,59,60 prThree studies ,54,56 prWe performed a risk of bias assessment with the RoB-2 tool . The assCaffeine is categorized as a central nervous system stimulant and is composed of methylxanthine . Its maiIn adults without any diagnosed mental disorders, caffeine at doses up to approximately 300 mg improves cognitive processes such as reaction time and attention with minimal side effects . Some leFurthermore, caffeine and caffeine-containing beverages, such as coffee and tea, appear to act as protective factors when consumed regularly ,68. CoffSeveral recent studies in animal models ,70,71 ha2 = 0%).However, our review showed that, at least in the current literature, there are few signs that caffeine improves the general symptoms of ADHD. Three of the five studies ,57,59 reThe systematic review also showed no benefit in the outcome of impulsivity in two studies, with evidence of harm (increased impulsivity) by caffeine in one study . SimilarSome of the studies included in our review ,57,59,60Non-randomized studies on the effects of caffeine use in patients with ADHD have similarly shown conflicting results. A study involving 25 children reported that caffeine did not help any patient and in fact worsened symptoms in some of them . In cont2 = 1%) [Comparatively analyzing the results of caffeine with off-label medications for ADHD, it is found that antidepressants appear to be more promising than caffeine. A meta-analysis with a similar methodology compared placebo with tricyclic antidepressants in children with ADHD . The res2 = 1%) . This fi2 = 1%) .A network meta-analysis compared amphetamines, atomoxetine, bupropion, clonidine, guanfacine, methylphenidate, and modafinil in the treatment of core symptoms of ADHD in children and adolescents . In thisSome recent studies ,81,82,83The limitations of this systematic review and meta-analysis should be acknowledged. First, it should be noted that there are few randomized controlled trials in the literature on this topic and that each study involves a small number of patients. Consequently, there is a vital need for more trials to enhance the evidential basis. Nevertheless, our meta-analysis represents the largest aggregate population comparing caffeine vs. placebo in a randomized pediatric population with ADHD. Second, the studies used different tools for outcome assessment. Therefore, we used a standardized mean difference for comparison of the continuous outcome between groups. Third, there were different doses of caffeine between studies.The totality of evidence in randomized controlled trials comparing caffeine with placebo for treatment of ADHD symptoms in children suggests that there is likely no benefit of caffeine for management of general symptoms such as hyperactivity, inattention, and impulsivity in this patient population. For the advancement of ADHD therapy, it will be of greater importance to seek new molecules for the treatment of this disorder.


Attention-deficit hyperactivity disorder is a common disorder that affects both children and adults. However, for adults, little is known about ADHD-attributable medical expenditures.To estimate the medical expenditures associated with ADHD, stratified by age, in the US adult population.Using a two-part model, we analyzed data from Medical Expenditure Panel Survey for 2015 to 2019. The first part of the model predicts the probability that individuals incurred any medical costs during the calendar year using a logit model. The second part of the model estimates the medical expenditures for individuals who incurred any medical expenses in the calendar year using a generalized linear model. Covariates included age, sex, race/ethnicity, geographic region, Charlson comorbidity index, insurance, asthma, anxiety, and mood disorders.N = 83,776).Adults (18 +) who participated in the Medical Expenditure Panel Survey from 2015 to 2019  were classified as having ADHD. The estimated incremental costs of ADHD in adults were $2591.06 per person, amounting to $8.29 billion nationally. Significant adjusted incremental costs were prescription medication , which accounted for the largest portion of total costs, and office-based visits . The adjusted incremental costs for outpatient visits, inpatient visits, emergency room visits, and home health visits were not significantly different. Among older adults (31 +), the incremental cost of ADHD was $2623.48, while in young adults (18–30), the incremental cost was $1856.66.The average medical expenditures for adults with ADHD in the US were substantially higher than those without ADHD and the incremental costs were higher in older adults (31 +) than younger adults (18–30). Future research is needed to understand the increasing trend in ADHD attributable cost. DSM-5).1,2 ADHD is characterized by a repeated set of inattentive or hyperactive-impulsive behaviors that occurs throughout multiple settings and impairs social, academic, or occupational functionality.3 An estimated 10–60% of children with ADHD continue to experience symptoms throughout their lives.4 ADHD is a common psychiatric disorders experienced by adults,5 with a prevalence around 4.4%,6 and is one of the most commonly treated disorders in young adults.7Attention-deficit hyperactivity disorder (ADHD) is a neuropsychiatric disorder that is normally diagnosed in childhood but may persist into adulthood. According to the Diagnostic and Statistical Manual of Mental Disorders 29. Briefly, for households that participated in the study, 5 rounds of interviews were conducted within 2 years to collect a broad range of information about all members in the household. The survey collects information on self-reported sociodemographic characteristics, health status, health conditions, medical diagnosis, insurance status, use of healthcare services, expenditures for different types of services, and sources of payment. The occurrence of health conditions is determined primarily by prompting respondents of the household component for the causes of medical events and disability episodes for themselves or their family members or asking them about any health conditions that are bothering the person or their family members during the reference period30. These conditions are then coded by medical professionals, regardless of whether any medical expenses occurred in that year.Data were obtained from the Medical Expenditure Panel Survey (MEPS) for 2015–2019. MEPS data are a nationally representative sample of the US civilian noninstitutionalized populationDue to the de-identified data, this study was exempt from institutional review board approval, per the US Department of Health and Human Services guidelines.31,32 After excluding individuals with missing values on key variables, the final sample included 83,776 adults.The inclusion criteria for this study was men and women aged 18 years or older. Individuals who reported a diagnosis of ADHD (ICD-9 = 314 or ICD-10 = F90) for the period January 1, 2015, to December 31, 2019, were classified as ADHD.33The dependent variables for this study were the direct overall medical expenditures and the service specific medical expenditures. This included hospital stays, outpatient care, emergency room visits, physician office visits, home care visits, and prescription medication. Household members were asked about which medical services each family member used and the corresponding medical costs that occurred. These costs included respondents’ out of pocket payments and payments from private/public health insurance but did not include over-the-counter drugs, as these were not collected by MEPS. Following the guidelines recommend by AHRQ, costs were inflated to the recent estimate of the 2019-dollar value using the Personal Health Care Price Indices.5,25 Depending on the year the data was collected, medical conditions were defined using ICD-10-CM codes or the clinical classification codes generated from Clinical Classification Software (CCS).34 Medical conditions included an adapted Charlson Comorbidity Index (CCI), asthma (CCS = 128 or ICD-10 = J45), anxiety disorders  (CCS = 651 or ICD-10 = F40/F41), and mood disorders  (CCS = 657 or ICD-10 = J31/J32).4,5 The CCI is a commonly used method of categorizing medical comorbidities of patients based on their ICD codes.35 The CCI score was calculated using Stata’s Charlson package, which is based on the adaptations of Deyo and Quan to accommodate ICD-9-CM codes and ICD-10-CM codes.38 For this study, the CCI was grouped into 3 categories: 0, 1, ≥ 2. Asthma was included as a covariate in the model due the high comorbidity found between ADHD and asthma.4 Although the exact nature of the association is not fully understood, numerous studies have observed the association in adults and children, and in population and clinical settings.39 Anxiety disorders and mood disorders have also been found to have a significant association with ADHD in adults and were thus included in the final model.5,40 Alcohol- and drug-related abuse were not adjusted in the model as previous research found that ADHD generally precedes these behaviors, and that ADHD can contribute to their development.42From the literature, two groups of variables, patient characteristics and medical conditions, were identified as potential predictors of the medical expenditures of ADHD. Patient characteristics included age, gender, race/ethnicity, geographic region, marital status, employment status, education, poverty, and insurance type.t-statistics for continuous variables. Next, a two-part model was used to estimate the overall and service specific medical expenditures associated with ADHD in US adults. A two-part model was chosen due to the large number of individuals who reported zero medical costs within the calendar year.43,44 The first part of the model predicts the probability that individuals incurred any medical costs during the calendar year using a logit model. The second part of the model estimates the medical expenditures for individuals who incurred any medical expenses in the calendar year using a generalized linear model. The modified park test was used to select the distribution and variance function for the generalized linear model, resulting in gamma or Poisson distribution and a log link function. Covariates included in both parts of the model were age, sex, race, ethnicity, geographic region, insurance type, CCI, asthma, anxiety, and mood disorders. Stratified analysis was conducted by age for younger adults (18-30) and older adults (31 +).Bivariate analysis was conducted between individuals with ADHD and those without ADHD using chi-square statistics for categorical variables and 45 First, assuming everyone had ADHD (A), second assuming everyone did not have ADHD (B), and finally determining the incremental costs of ADHD by subtracting the predicted costs when everyone did not have ADHD from the predicted costs when everyone did have ADHD (A-B). This difference was then multiplied by the average number of individuals with ADHD to estimate the national economic burden of ADHD. The number of individuals with ADHD was estimated directly from MEPS by applying sampling weights, using all possible individuals. Sampling weights were taken into account in all cost estimation analysis, which were 5-year pooled sampling weights averaged by the number of panels (N = 5). The bootstrap method with 100 replicates was used to derive standard errors (SEs) and 95% confidence intervals (CIs).Based on the two regression models, per-person expenditures associated with ADHD were calculated through several steps.p-value of 0.05.All analyses were conducted using Stata software  and statistical significance was determined at a p = 0.005). When only including patients who had a medical expenditure, the overall unadjusted mean medical expenditures was $8009.25 (SE: 111.43), and the difference between for those with ADHD ($8697.59 ± 649.89) vs those without ADHD ($7994.45 ± 110.54) was insignificant.In the study population Table , 1.44% (p < 0.001), more likely to be White , and more likely to have private insurance . In contrast, individuals without ADHD were more likely to be married  and have the highest educational attainment be a high school degree or equivalent . Medically, individuals with ADHD were more likely to report asthma, mood disorders, and anxiety.Individuals with ADHD were significantly different from those without ADHD regarding patient characteristics and medical conditions. For patient characteristics, individuals with ADHD were more likely to be younger  than individuals without ADHD to have an expenditure of at least $1, and among individuals with positive expenditures, those with ADHD had 28% (exp[0.25]) higher expenditures than individuals without ADHD   in individuals with ADHD than individuals without ADHD in adults 18–30 and 28.50 times higher  in adults 31 + (Table p = 0.029) than adults without ADHD and adults 31 + with ADHD had 25% higher expenditures . The total incremental cost was higher in adults 31 + than among younger adults 18–30, $2623.48 (95% CI: $997.94–$5012.65) and $1856.66  respectively , the incremental cost of ADHD was $2623.48, while in younger adults (18-30) the incremental cost was $1856.66. The largest proportion of medical expenditures across all age groups was associated with prescription medication.45,46 In 2011, Hodgkins et al. analyzed data from two large healthcare claims and productivity databases and found adults with ADHD incurred an excess of $2100.76 (adjusted to 2019-dollar) more in medical expense.5 More recently, Shah and Onukwugha analyzed MEPS data from 2017 to 2018 and found that working adults with ADHD incurred $4328 more than working adults without ADHD.46 Although their findings of the total costs of ADHD are higher than ours, this is likely due to the differences in inclusion criteria for their study sample, which was restricted to adults who were employed in the study year. Employment status has a significant impact of healthcare utilization and costs, with unemployed individuals less likely to visit physicians for preventative services and less likely to fill prescriptions.47,48 This impact may be even greater in individuals diagnosed with ADHD, as ADHD medication can be expensive and often requires frequent visits to the physician for proper management.49,50 By including all adults, regardless of insurance or employment, our findings allow for a more complete understanding of the financial impact of ADHD in adults.Our study demonstrates that individuals with ADHD incurred higher medical expenditures compared to individuals without ADHD. The estimated incremental costs of ADHD per person found in this study are consistent with previous studies conducted in the US, highlighting the continued impact of ADHD on medical expenditures.25 These results indicate that the medical cost of ADHD has a substantial economic impact in the US and policy initiatives might be needed to alleviate this economic burden. This is especially troubling since ADHD also results in additional costs to society, such productivity and income loss, education, and justice system.25,51 Furthermore, although the ADHD prevalence found in our study, 1.44%, is similar to the prevalence found in a recent study using Kaiser Permanente data27, 1.12%, it is less than the 4.4% that is commonly cited by other studies.25,51 Therefore, our estimated medical expenditures associated with ADHD at the national level are a relatively conservative assessment.On a national level, the estimated $8.29 billion for total medical costs is consistent with findings from previous studies of $1.32–$39.79 billion .52 This extra burden of medical expenditure among older adults with ADHD might reflect the lifetime accumulative burden of illness from ADHD, a topic which deserves more academic and clinical attention . More research is needed to understand why the incremental cost is so much higher in older adults than in younger adults and how to address this increased cost.In this study, stratification into two age groups provided additional insights into ADHD medical expenditures. We found that ADHD medical expenditures were higher in older adults (31 +) than younger adults (18-30), which is consistent with a recent study conducted in Germany.23,46 Although there are several treatment options for individuals with ADHD, pharmacological treatments, i.e. medications, are the most commonly utilized.53 Consequently, this leads to higher medical expenditures due to prescription medication in individuals with ADHD. However, other potential treatment options, such as mindfulness-based cognitive therapy, need to be explored more fully.54 Unfortunately, the majority of cost-effectiveness research on the treatment of ADHD has been focused on children.53 Our findings indicate that more cost-effectiveness research for ADHD treatment is needed in adults to provide affordable, high-quality care for everyone with ADHD.In our study, prescription medication was the largest component of the total medical expenditures for ADHD for all adults, and within each age group. These findings are consistent with previous studies of adult and children/adolescent populations.55 Another strength of MEPS data is that it includes the total payments respondents reported which were paid. Finally, this study used a two-part model to estimate the medical expenditures. The two-part model has a long history in health economics and health services research due to its ability to model continuous, non-negative outcome measures.56 The model is able to handle data that has a skewed conditional distribution, a large number of zero values, and allows for investigation of the effects of demographic and clinical comorbidities on both the logit model and GLM model separately.56,57As compared with past studies, one of the main strengths of our study is that it used a large, nationally representative sample to estimate medical expenditures, including individuals with and without insurance and nonworking adults. This allows for the fact that individuals with ADHD could have difficulty with employment, which affects their likelihood of having insurance and thus did not enter the data sources provided by payers.58 Second, current DSM-5 criteria for ADHD have been criticized for having low clinical thresholds, which results in a misclassification of individuals who do not experience the symptoms of ADHD being classified with the diagnosis.59,60 In our study, this would lead to an underestimation of the medical expenditures associated with ADHD since not all individuals in the ADHD cohort would truly have the diagnosis. Third, our national cost estimates were likely to be underestimated because MEPS did not include people who were incarcerated. This is important because the ADHD rates have been reported as high as 25.5% in prisoners.40 Fourth, as MEPS data is cross-sectional, the results can only be interpreted as medical expenditures associated with ADHD and cannot account for costs associated with ADHD over a lifetime. Finally, our study did not include indirect cost associated with ADHD, such as productivity and income loss, education, and justice system.This study has several limitations. First, the MEPS data is based on self-reported responses and only includes ADHD if an individual is currently being managed for the disorder or it is identified as a current problem. This might explain why our estimates of ADHD rate (1.44%) are lower than some worldwide estimates (1.0–5.4%).ADHD is a common psychiatric disorder that impacts a large number of adults in the US. We found that the average medical expenditures for adults with ADHD in the US were substantially higher than those without ADHD and the incremental costs were higher in older adults (31 +) than in younger adults (18-30).


ObjectiveAttention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder characterized by impaired levels of inattention, disorganization and/or hyperactivity-impulsivity. The aim of this study was to estimate the prevalence of ADHD among primary school children in Jordan and assess the potential risk factors.MethodA cross-sectional study was conducted in 2022-2023 on 1563 school children aged six to 12 years. ADHD was assessed using parent and teacher versions of the Conners Rating scale. Risk factors were evaluated through a sociodemographic questionnaire. A p-value set at <.05 was considered statistically significant.ResultsADHD prevalence based on parents' and teachers' perspectives was 27.7% and 22.5%, respectively. Males, smoking during pregnancy, low birth weight, low parental education and unemployment, and public schools had increased ADHD rates. ConclusionADHD presents a major problem among primary school children in Jordan. Early detection, prevention, and management of this disease require parents' and teachers' awareness and risk factor control. Attention deficit hyperactivity disorder (ADHD) is characterized by a pattern of inattention, disorganization, and/or hyperactivity-impulsivity with impaired functioning in academic, social, or occupational activities . It is aThe Diagnostic and Statistical Manual of Mental Disorders fifth edition DSM-5) lists a number of symptoms of ADHD, including a failure to pay close attention to details, difficulty sustaining attention, not listening when spoken to directly, failure to finish schoolwork, difficulty organizing tasks, reluctant to engage in tasks that require sustained mental effort, losing things necessary for tasks, easily distracted, forgetful in daily activities, fidgeting, leaving the seat in situations when remaining seated is expected, unable to play quietly, acting as if "driven by a motor", talking excessively, difficulty waiting in turn and interrupting others at rates that are disproportionate to the person's age or stage of development ,5. These lists a ADHD is the most common neurodevelopmental disorder in children . StudiesThe etiology of ADHD is multifactorial, involving both genetic and environmental variables . ADHD haPatients with ADHD often also suffer from co-occurring mental health issues or comorbidities, such as depression, anxiety, a learning disability, or a behavioral condition, such as conduct disorder or oppositional defiant disorder. Moreover, they are more likely to engage in dangerous activities like substance abuse, delinquency, and traffic accidents, making ADHD a serious public health issue ,12.In Jordan, the prevalence of ADHD in schoolchildren has not been previously studied from the perspective of both parents and teachers. This study aimed to determine the prevalence of ADHD among school-aged children in Jordan, as well as potential risk factors associated with this condition.This article was posted as a preprint on Research Square on 2/24/2023. A cross-sectional descriptive study was conducted at public and private primary schools in Amman, the capital of Jordan, during the study year of 2022-2023. Children of both genders aged six to 12 years old were included in the survey. After approval from Al-Balqa Applied University's Institutional Review Board (IRB number: 26/3/1/944) and the Ministry of Education , a psychologist visited the schools to explain the study's objectives and methodology to the principals in order to obtain their permission to distribute the questionnaires. Information was gathered for the study by self-administered questionnaires. The questionnaire for parents is divided into two parts. The child's age, gender, and health conditions, as well as the parents' occupation and level of education, were among the demographic details and potential factors uncovered in the first section. In the second part, parents and teachers used the Arabic version of a 10-item Conners Rating Scale for ADHD to evaluate the child. Teachers and parents were informed that all data collected for the study would be kept confidential and used exclusively for research. The classroom teacher filled out a questionnaire about each student, and the parents of those students filled out another questionnaire that was sent home in their child's backpack.The sampling plan was stratified and proportionally allocated to ensure a representative sample of the research population. Eight elementary schools were chosen randomly. Using a simple random method, classrooms from these schools were selected at random. All students who were present in these selected classrooms were included in the study. A total of 2400 students were approached, and 1563 agreed to participate in the study, with a response rate of 65%. Due to incomplete questionnaires, almost a quarter of the sample was excluded from the study.The 10-item Conners Rating Scale comprises the 10 items with the highest loading from the original Conners Parent and Teacher Rating Scales, along with updated normative data . Each itData analysis was performed using the SPSS statistics program . Percentage and frequency were used for categorical variables. Chi-squared test was used to examine the association between sociodemographic variables and ADHD. Multiple binary logistic regression analysis was performed to assess ADHD predictors. The intraclass correlation and Cohen's kappa were used to investigate parent-teacher agreement. A p-value of <.05 was considered statistically significant.Our study included 1563 children, who ranged in age from six to 12 years old. Of these, 770 were boys (49.0%), and 790 were girls (51.0%). The sociodemographic characteristics and potential risk factors are described in Table (1)Prevalence of ADHD and associated factorsIn our study, the prevalence of ADHD, according to parents' perspective, was 27.7%, and according to teachers' perspective was 22.5%. Regarding associated factors, males were substantially more likely than females to have ADHD . In public schools, 32.3% of students had ADHD compared to 22.1% in private schools (p<0.001). In addition, low parental education was found to be significantly associated with ADHD (<0.001 for fathers and 0.002 for mothers). The prevalence of ADHD among children of unemployed fathers  and unemployed mothers  was shown to be statistically significant. The study indicated that 51.7% of mothers who smoked during pregnancy had a child with ADHD, compared to 27.2% of non-smoking mothers (p=0.004). In addition, a significant proportion of children with ADHD had low birth weight (p<0.001). In contrast, neonatal diseases and season of birth had no significant connection with ADHD. Table Predictors for ADHDThe significant variables in bivariate association  were nominated to be entered into backward multiple binary logistic regression to investigate their contributions to ADHD. Four predictors out of eight were left over in the final model, with the amount of Nagelkerke R square 11.3% of ADHD variance explained by gender, school type, smoking during pregnancy, and birth weight. Moreover, the confusion matrix revealed that the overall model accuracy was 75.1%. The accuracy of the binary logistic regression model was also investigated using the receiver operating characteristic (ROC) curve  with mixed-way effect and the absolute agreement was found to be 0.434, indicating that both raters (parents and teachers) had a low level of agreement. According to Cohen's kappa for dichotomous agreement, parents and teachers had a low agreement on classifying children as having positive or negative ADHD (kappa of 0.212).ADHD is one of the most prevalent neurodevelopmental disorders among children, and it is frequently observed in school-aged students, which may provide an opportunity for early detection and management. Meta-analyses have found a wide range of conflicting estimates of the prevalence of ADHD . AccordiAccording to our study, children had an ADHD prevalence of 27.7% according to parents and 22.5% according to teachers, which is within the range of prevalence of ADHD in 11 Arab countries . In Jordan, only two studies with vastly different ADHD prevalence percentages have been published: one in the Al-Qasr area in the south of Jordan with a prevalence of 6.24%, studied on 4374 students according to a teacher's questionnaire and using the fourth edition of Diagnostic and Statistical Manual (DSM4) , and theA study conducted in Saudi Arabia revealed that the prevalence of ADHD ranged from 21.3% to 35.34%, according to the ADHD subtypes . AnotherThe present study documented that being male was significantly correlated with ADHD, which is similar to international literature , althougSimilar to Langley et al.'s study , our stuIn contrast to our findings regarding neonatal disorders, a study conducted in China revealed that during their growing stage, infants with jaundice were at high risk for having ADHD, as determined by a physician . Season According to our data, we found low agreement between parent and teacher scales since it's a subjective measurement, which is consistent with a study done in the United Arab Emirates . This study is the first in Jordan to use the 10-item Conners rating scale, which is a brief and valid instrument for assessing and screening for ADHD , and to LimitationsThis research was only carried out in Amman; therefore, the extent to which its findings can be generalized is restricted. Another limitation is that there was no clinical interview to verify the ADHD diagnosis. ADHD is a highly prevalent problem among primary school children in Jordan. The prevalence was found to be higher than the international values. To date, this is the first study in Jordan to focus on crucial risk factors such as smoking during pregnancy, birth weight, and parental occupation, as well as to involve both parents and teachers as informants to assess the prevalence of ADHD. These findings underline the importance of increasing ADHD assessment and monitoring among schoolchildren from various socioeconomic backgrounds as well as dealing with modifiable risk factors. They also emphasize the significance of obtaining correct diagnoses and providing culturally appropriate care.


BackgroundAttention-deficit hyperactivity disorder (ADHD) is a public health challenge because it may contribute to academic and psychological difficulties among school children. Though ADHD is a common problem, Taif teachers' knowledge of the disease has never been assessed. Therefore, this study aimed to determine factors that influence ADHD knowledge among female primary schoolteachers in Taif City, Saudi Arabia.MethodsThis cross-sectional study was conducted on 359 female schoolteachers recruited by stratified random sampling. Participants self-reported demographic and personal data and completed the validated Arabic version of the knowledge of ADHD scale and teacher’s attitude toward ADHD questionnaires.ResultsIn Taif, it was determined that 96.4% of female primary schoolteachers had insufficient knowledge of ADHD, notably with nature, causes, consequences, and treatment knowledge. In contrast, 40% had adequate knowledge of the condition's symptoms and diagnosis, and 97.5% exhibited a favorable attitude. There is significantly higher knowledge among private schoolteachers, those who freshly graduated, specialize in learning difficulties, who attended any course/training about ADHD, and whoever taught ADHD children. There was a significant positive weak correlation between teachers’ knowledge of ADHD and their attitude. Regression analysis revealed that female schoolteachers specialized in learning difficulties show significantly higher knowledge scores, teachers who never taught an ADHD child had a reduction of 94.6 % in ADHD knowledge, and any increase in the number of ADHD children teachers teaches has significantly increased teachers’ knowledge .ConclusionsOur study showed that there was a serious knowledge gap on ADHD among Taif female primary schoolteachers. Therefore, it is strongly recommended to boost teachers' knowledge of ADHD, especially at government schools, through conducting training courses, distributing leaflets intended to address ADHD, and launching awareness campaigns through the media, including social media, television, and radio. It is also recommended that education faculty curricula should include more information on ADHD. Attention-deficit hyperactivity disorder (ADHD) is a critical disorder affecting school-aged children . It inclStudies of ADHD-associated factors focus mainly on prenatal and perinatal factors , environmental lead exposure , and traThe American Academy of Pediatrics recommends a combination of medication and behavior therapy, parent training on behavior management, behavioral classroom intervention, educational interventions, and individualized instructional supports, including school environment, class placement, instructional placement, and behavioral supports, which are a necessary part of any treatment plan for ADHD children aged 6 years to 12 years. Some nonmedication treatments for ADHD-related problems have either too little evidence to recommend them or have been found to have little or no benefit. These include mindfulness, cognitive training, diet modification, electroencephalography biofeedback, and supportive counseling . HoweverSince ADHA impairs academic performance, which is culturally highly valued in the Arab world , teacherADHD tends to be noticed at an early age and may become more noticeable when a child starts school. Most cases are diagnosed when children are 6 to 12 years old ,5. GivenDesign and study populationA cross-sectional study was carried out on Saudi female primary schoolteachers from the private and governmental sectors in Taif City, Saudi Arabia, between December 2022 to April 2023. The study was conducted at primary schoolteachers, under the Ministry of Education in Taif City in the western province of Saudi Arabia. The total number of girls’ primary schools in Taif City is 112. A multi-stage stratified random sampling technique was used. In the first stage of sampling, Taif City was divided into four educational districts. In the second stage, stratification was based on the type of school; six primary schools  were randomly selected from each district. In the subsequent stage, the predetermined sample was proportionally allocated to the selected schools according to their teachers’ numbers. Finally, a systematic random sampling of every second female teacher was used to choose participants from each school until the predetermined sample was fulfilled. The study authors distributed the study questionnaire themselves. In each district, questionnaires were to be gathered over the course of a month from different schools. Teachers who are non-Saudi or those working in administrative positions like principals and admin staff of the schools were excluded. It is noteworthy to mention that the response rate was 96.24%. Using the 2002 Epi Info™ software , a minimum required sample of 373 samples was determined based on the knowledge of teachers about ADHD (41.61%) [MeasuresFemale teachers filled out a self-reported questionnaire that consisted of three sections:Demographic QuestionnaireSection A comprised demographic questions that covered age, nationality, marital status, educational level, occupational experience years, school type, teaching specialty, and previous experience with ADHD students. In addition, this study measured where the participants received information  about ADHD or whether they already have a child with ADHD.Knowledge of Attention‑Deficit Disorders ScaleSection B of the tool assessed the schoolteacher’s knowledge of ADHD by using the Knowledge of Attention-Deficit Disorders Scale (KADDS). It is a widely used screening instrument used to assess the level of knowledge of teachers regarding ADHD and was developed by do Sciutto and his colleagues. It has been established as a reliable and valid instrument  . The intTeachers Attitudes Toward ADHDSection C of the study instrument assessed the teacher’s attitudes toward ADHD by using a 12-item. The questionnaire was already available in the Arabic language, and it showed adequate reliability among Saudi teachers as evaluated by Cronbach’s alpha (α= 0.84) to assess teachers' attitudes toward ADHD . Items wStatistical analysisStatistical analyses were performed using SPSS Statistics version 24 . The teacher’s knowledge score was computed, converted into a percentage score, and categorized according to the total knowledge score into two categories as described in a previous study: insufficient (mean score ≤60%) and good (mean score > 60%). Likewise, the schoolteacher’s attitude score was computed and converted into a percentage score, and teachers who scored ≥ 60.0% were considered as having a favorable attitude toward ADHD ,24. DescThe characteristics of the study participants are presented in Table ADHD knowledge was classified into a sufficient knowledge group (3.6%) and an insufficient knowledge group (96.4%). The median ADHD knowledge score was 13 and IQR was 0-25. Different rates of ADHD knowledge subscales are presented in Figure Table The attitude toward ADHD among female primary schoolteachers in Taif City is illustrated in Figure The relationship between knowledge, attitude toward ADHD, and demographic data among female primary schoolteachers is demonstrated in Table Table The ADHD knowledge, attitude, and demographic data among female primary schoolteachers in Taif City, Saudi Arabia, were illustrated using adjusted ORs and their confidence intervals in Table . LogistiIn this research, we explored ADHD knowledge and attitude of female primary schoolteachers in Taif City, Saudi Arabia, and studied factors that influence ADHD knowledge among Taif female schoolteachers. Results showed that more than 96% have poor ADHD knowledge, especially general and treatment ADHD knowledge. Saudi studies in Makkah, Jeddah, and Abha cities  ,26 and oHaving recently graduated, being younger, or gaining knowledge during the study years had a beneficial impact on the level of teachers' knowledge of ADHD in the current study. This might be a result of the newly strengthened curricula that place an emphasis on ADHD. Moreover, schoolteachers who had never heard of or attended training on ADHD scored significantly higher on the knowledge scale; attending a course or training on ADHD is a form of professional development that can help teachers develop specialized knowledge and skills related to working with students with ADHD. Information about effective classroom strategies, behavior management approaches, and accommodations that can assist students with ADHD to succeed in school may be included in this professional development training. Alshehri et al. (2020) reported that teachers’ ADHD knowledge was significantly improved immediately after the teachers' training . These fThe current study highlighted the relationship between teachers' high knowledge of ADHD and their specialization in learning difficulties or previous experience working with a child with ADHD. Importantly, the regression analysis revealed that teachers who had never taught an ADHD child had a reduction of 94.6% less ADHD knowledge than those who had. These findings highlighted the importance of providing teachers with training and support to improve their understanding of ADHD even if they had not yet taught a child with the disorder. This may explain why schoolteachers specializing in learning difficulties have significantly higher knowledge scores than those with other specializations. This is concordant with Al‑Moghamsi et al.  who founRegarding factors associated with the participant’s attitude toward ADHD; public school instructors who are older, have more years of experience, and have a post-graduate degree are more likely to have positive attitudes toward students with ADHD. Plausible explanations for such findings could be attributed to co-occurrences of higher years of experience and the likelihood of working with a larger number of students with ADHD and the accumulation of information through either experience or education . This exThere are a number of strengths of this study, including the inclusion of an appropriate sample size, enrollment of a random sample, inclusion of private and public schools from different taif districts, and the use of a reliable and valid tool. Furthermore, this is the first study in Taif to examine teachers' ADHD knowledge. However, there are also some limitations to consider. Firstly, the collection technique was self-reported data, which may involve recall bias. Secondly, data were based on a cross-sectional and causation cannot be assured. Finally, the study included only female teachers because the Saudi Ministry of Education issued a Cabinet Resolution about the early childhood initiative aimed to enhance enrolment and performance levels in the primary classes by assigning only female teachers to teach young male and female pupils starting in 2019. Interventional studies are recommended to assess the change in schoolteachers' ADHD knowledge after training.In conclusion, this study highlights three major important issues for primary school children's health in Taif. First, teachers’ scores on KADDS were very low compared to previous research conducted in other Saudi cities, indicating a serious knowledge gap on ADHD. Second, teachers' prior experience with ADHD, training, and specialization on learning difficulties were all positively associated with their level of knowledge of ADHD. Third, teachers' attitude toward ADHD is correlated positively with their knowledge.


Synbiotic 2000, a pre + probiotic, reduced comorbid autistic traits and emotion dysregulation in attention deficit hyperactivity disorder (ADHD) patients. Immune activity and bacteria-derived short-chain fatty acids (SCFAs) are microbiota–gut–brain axis mediators. The aim was to investigate Synbiotic 2000 effects on plasma levels of immune activity markers and SCFAs in children and adults with ADHD. ADHD patients (n = 182) completed the 9-week intervention with Synbiotic 2000 or placebo and 156 provided blood samples. Healthy adult controls (n = 57) provided baseline samples. At baseline, adults with ADHD had higher pro-inflammatory sICAM-1 and sVCAM-1 and lower SCFA levels than controls. Children with ADHD had higher baseline sICAM-1, sVCAM-1, IL-12/IL-23p40, IL-2Rα, and lower formic, acetic, and propionic acid levels than adults with ADHD. sICAM-1, sVCAM-1, and propionic acid levels were more abnormal in children on medication. Synbiotic 2000, compared to placebo, reduced IL-12/IL-23p40 and sICAM-1 and increased propionic acid levels in children on medication. SCFAs correlated negatively with sICAM-1 and sVCAM-1. Preliminary human aortic smooth-muscle-cell experiments indicated that SCFAs protected against IL-1β-induced ICAM-1 expression. These findings suggest that treatment with Synbiotic 2000 reduces IL12/IL-23p40 and sICAM-1 and increases propionic acid levels in children with ADHD. Propionic acid, together with formic and acetic acid, may contribute to the lowering of the higher-than-normal sICAM-1 levels. Attention deficit hyperactivity disorder (ADHD) is a common childhood-onset neurodevelopmental psychiatric disorder with about 5% worldwide prevalence among children and adolescents and 3% in adults . The corPreclinical studies from germ-free and antibiotic drug-treated mouse models have shown that the absence or alteration of normal gut microbiota early in life has significant effects on immune activity , stress http://www.hmdb.ca, accessed on 15 September 2022). Succinic acid is an intermediate metabolite in the fermentation towards propionic acid. SCFAs are multifunctional molecules, being not only an essential energy source for local intestinal cells  = 0.0022) and sVCAM-1 (pFDR = 2.9 × 10−5) were significantly higher in ADHD patients compared to healthy control , fractalkine (pFDR = 0.050), TGF-β3 (pFDR = 0.049), and TRAIL (pFDR = 0.039) were lower in ADHD as compared to family members only, and eotaxin-1 (pFDR = 0.042) were higher as compared to unrelated controls only (pFDR = 2.4 × 10−4), IL-2Rα (pFDR = 1.2 × 10−5), sICAM-1 (pFDR = 1.6 × 10−7), sVCAM-1 (pFDR = 1.4 × 10−7), TGF-β2 (pFDR = 0.014) and TRAIL (pFDR = 7.6 × 10−4) levels were higher in children, while CRP (pFDR = 0.041) and eotaxin-1 (pFDR = 0.0013) levels were higher in adults. This suggests that children and adults with ADHD have different profiles of immune activity marker levels in plasma. In addition, sex-disaggregated statistical analyses showed that the levels of IL-10 were higher in boys vs. girls with ADHD, while eotaxin-1 (pFDR = 0.0037) and IL-16 (pFDR = 0.024) were higher and IL-12/IL-23p40 (pFDR = 0.0037) and SAA (pFDR = 0.00037) were lower in adult males vs. females with ADHD  (pFDR-child = 0.050), we stratified the analysis by current ADHD medication [yes/no]. For children who were currently on ADHD medication, Synbiotic 2000 manifested a significant reduction of IL-12/IL-23p40  and a suggestive reduction in sICAM-1 levels  compared to placebo (p = 0.049). For children and adults who were not currently on ADHD medication, Synbiotic 2000 suggestively increased the levels of VEGF-A   and sIL-2Rα  by Synbiotic 2000 compared to placebo (p = 0.037)  A. Since  placebo D. For ch= 0.043) . This su placebo . Adults = 0.037) , which w= 0.037) .p = 4.4 × 10−4) and propionic acid (p = 0.0064) as compared to healthy controls  concentrations were significantly higher in family controls than in unrelated controls (p = 0.00011), acetic (p = 0.016), propionic (p = 4.3 × 10−5), and butyric acids (p = 0.014) were all lower in adults with ADHD as compared to adult family controls, while acetic acid concentrations (p = 0.0043) were higher in ADHD as compared to adult unrelated controls  were significantly correlated with each other in both controls and patients . The stacontrols A. Furthecontrols . The bascontrols .p = 1.3 × 10−8), acetic acid (p = 3.5 × 10−5), and propionic acid (p = 0.017) were significantly lower in children than in adults  (No significant changes in SCFA concentrations from baseline to follow-up were found neither for those on placebo nor those treated with Synbiotic 2000 for neither children nor adults . However 0.046.) .p = 0.0057). In the sensitivity analysis where we stratified for ADHD medication, we found that Synbiotic 2000, compared to placebo, suggestively reduced formic acid levels in adults who were not on ADHD medication at sampling (As shown in sampling .pFDR < 0.050), while formic and propionic acid levels were suggestively negatively correlated with sICAM-1 and sVCAM-1 (p < 0.050). Further, baseline acetic acid in children correlated positively with pro-inflammatory eotaxin-1 (pFDR < 0.050) and suggestively positively to IL-12/IL-23p40 and TRAIL (p < 0.050) . In children with ADHD, baseline acetic acid levels were significantly negatively correlated with pro-inflammatory sICAM-1 and sVCAM-1 (< 0.050) ; however< 0.050) . The sig< 0.050) . The neg< 0.050) D. Additi< 0.050) .To further validate the negative correlations between SCFAs and sICAM-1, we did three independent in vitro experiments in human aortic vascular smooth muscle cells. Our results showed lower IL-1β-induced ICAM-1 expression when the cells were pre-incubated with formic acid, acetic acid, or propionic acid of the concentrations found in plasma .controls is only 4. However, we show that children with ADHD at baseline have higher IL-12/IL-23p40 and IL-2Rα levels than adults with ADHD, and children on ADHD medication have higher sICAM-1 levels than ADHD children without medication and adults. A previous report has shown childhood IL-12/IL-23p40 levels to be lower than adulthood levels [This study is the first to report the effects of a synbiotic intervention on plasma levels of immune activity markers and SCFAs in children and adults with ADHD. We previously reported that this intervention in an RCT design reduced autistic traits in children and improved emotion regulation in adults with ADHD . Now, wed levels . This sud levels  and IL-2IL-12 and IL-23 are heterodimers and share the p40 subunit called IL-12/IL-23p40. IL-12 and IL-23 promote Th1 and Th17 expansion, respectively, and are reported to be involved in the pathology of inflammatory bowel disease (IBD). The p40 subunit is a therapeutic target in IBD ,81. GI sNotably, the pattern of correlations between levels of immune activity markers and SCFAs detected in ADHD patients was not found in controls, suggesting that the associations between immune activity analytes and SCFAs are not generalizable beyond ADHD but depend on a complex regulation at physiological conditions . HoweverTo our knowledge, we are the first to report plasma levels of fractalkine, GRO-α, IL-12/IL-23p40, IL-18, IL-2Rα, TGF-β1, TGF-β2, TGF-β3, TRAIL, and VEFG-A in individuals with ADHD. The adult ADHD patients displayed at baseline different levels only of pro-inflammatory sICAM-1 and sVCAM-1 compared to the whole control group. Compared to the adults with ADHD, the children with ADHD had different baseline levels of eight of the immune activity markers and were hence analyzed separately. Most of these differences in marker levels between children and adults are not previously reported, neither in ADHD patients nor healthy individuals. Levels at baseline of eotaxin-1, fractalkine, MCP-1, TGF-β3, and TRAIL were higher in healthy family members of the ADHD patients than among healthy unrelated controls. Both genetic and environmental underpinnings may explain this, although there is no report showing that these markers are higher in persons with ADHD. The plasma SCFA concentrations at baseline of the patients and family controls of this study were previously reported to show lower levels of plasma formic and propionic acid in adults with ADHD compared to family controls after controlling for antibiotic drug exposure and other potential influencing factors . AccordiThe sample size of our RCT was relatively large, including 182 children and adults. An additional main strength is that the conducted in vitro experiments of SCFAs possible anti-inflammatory effect was at physiological SCFA levels. There are limitations to this study. First, there were only four healthy controls for children, and hence, we could not analyze this group. Therefore, we were unable to adequately relate the analyte levels in children with ADHD to reference values. Second, our data on medications with anti-inflammatory effects  or medications with gut microbiome effects   are not This exploratory study revealed that persons with ADHD, especially children on ADHD medication, have higher-than-normal pro-inflammatory sICAM-1 and sVCAM-1 and lower SCFA levels in plasma and that children with ADHD also have higher levels of additional pro-inflammatory markers, e.g., IL-12/IL-23p40 and IL-2Rα. Treatment with Synbiotic 2000, compared to placebo, reduced IL-12/IL-23p40 levels and suggestively reduced sICAM-1 and IL-2Rα levels in children. Synbiotic 2000 also suggestively increased propionic acid levels, which, together with highly associated formic and acetic acid levels, in turn, correlated negatively with sICAM-1 and sVCAM-1 in the children and protected against IL-1β-induced sICAM-1 expression in vitro. This suggests that Synbiotic 2000, in children with ADHD, reduces markers of intestinal and vascular inflammation, the latter in part through increasing SCFA levels. The findings warrant further studies to determine if persons with ADHD would benefit inflammation-wise from dietary intake of Synbiotic 2000 or a similar synbiotic.


We found a significant reduction in the mean number of parent-reported ADHD and HI symptoms from age 3 to 8 years, but otherwise similar mean numbers. Parent-reported ADHD symptoms were moderately correlated between ages, while correlations were low for teachers. A total of 77/108 (71%) of the children classified with parent-reported HI presentation at age 3 years were no longer classified within any ADHD presentation at age 8 years, the only clear trend across time for either informant. There was a low to moderate parent–teacher-agreement in the number of reported symptoms, and very low informant agreement for the classified ADHD presentations. Overall, clinicians should exercise caution in communicating concern about HI symptoms in preschool children. Age 3 years may be too early to apply the ADHD diagnostic symptom criteria, especially if parents and teachers are required to agree.Identifying attention-deficit/hyperactivity disorder (ADHD) in pre-schoolers may improve their development if treated, but it is unclear whether ADHD symptoms from this age are stable enough to merit treatment. We aimed to investigate the stability of parent- and teacher-reported ADHD symptoms and ADHD classified above the diagnostic symptom thresholds, including for hyperactivity-impulsivity (HI), inattention and combined presentations from age 3 to 8 years. This study is part of the longitudinal, population-based Norwegian Mother, Father and Child Cohort Study. At child age 3 years, parents were interviewed and teachers rated ADHD symptoms. At age 8 years, parents (The online version contains supplementary material available at 10.1007/s00787-022-02019-1. The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders DSM-5) defines Attention-deficit/hyperactivity disorder (ADHD) by at least six out of nine symptoms of hyperactivity/impulsivity (HI) and/or inattention (IA), present in two or more settings . The pre defines Obtaining information from both parents and teachers is recommended to ascertain that the ADHD diagnostic thresholds are present in at least two settings . Still, n = 118) administrating a diagnostic interview at seven timepoints between ages 4–6 and 11–13 years, found an overall significant decline of HI symptoms, but stable IA symptoms over time . Teachers indicated the similar number for HI and IA presentations at both ages, with only a slight across-time-agreement [κ = 0.06 (95% CI = 0.05–0.18)]. Table Table n = 328), the estimated parent–teacher agreement was small [κ = 0.22 (95% CI = 0.12–0.31)], but the parents and teachers agreed that 222 children were below the ADHD threshold at both time points. Only two children were above threshold according to both informants at both time points . When lowering the thresholds for parent HI and IA (to 5 symptoms), we identified a few more children at both ages, but this did not improve the stability.Our main findings were largely consistent with the four hypotheses. First, there was a significant reduction in the mean number of HI symptoms from age 3 to 8 years, but only for parents. For IA, there were similar mean numbers of symptoms at both timepoints, as hypothesized. Second, both parent- and teacher-reported ADHD symptoms at age 3 years significantly predicted ADHD symptoms reported by parents and teachers at age 8 years, respectively. Third, using categories, only 25% and 7% met the ADHD criteria at both timepoints according to parents and teachers, somewhat lower than hypothesized for parents. Also, in line with our hypothesis, we documented a large reduction in parent-reported HI presentation from preschool to school age, while teachers reported more similar rates at both ages. Fourth, there was very low parent–teacher agreement on ADHD classified above the diagnostic symptom thresholds, with only two children classified with ADHD according to both informants at both timepoints. Overall, our findings could suggest that age 3 years may be too early to apply the ADHD diagnostic criteria, especially if one requires parents and teachers to agree, in line with the recommendation from a previous study on young children .Our finding of a considerable drop in the number of HI symptoms is in concordance with epidemiological studies of preschool children , 11, andFor IA, we found low levels in the number of parent- and teacher-reported symptoms at age 3 years, in line with previous studies concluding that parent IA symptoms are rarely reported in pre-schoolers , 30, 32.Previous longitudinal clinical and high-risk studies have reported moderate to high ADHD stability from preschool to school age , 15, 35.For the present study, caution is warranted as we only had teacher-reports in a sub-sample, resulting in few children classified within the subgroups. Still, the low levels of teacher-reported HI and IA are in accordance with previous studies concluding that parent reports on ADHD symptoms may be more useful than reports from teachers , 37, andIn our study, both parents and teachers reported that a small percentage of children changed from HI at 3 years to IA at 8 years. This seems to be in line with the results from a population study following symptom trajectories concluding that the frequency of HI symptoms tended to slightly decrease with age, whereas the frequency of IA symptoms substantially increased to the age of 6 years . We alsoObtaining information from both parents and teachers is recommended to ascertain that the ADHD diagnostic thresholds are present in at least two settings. Our results could suggest that this may be too strict in early preschool years, in line with studies showing low parent–teacher agreement , 19, 30.Neither controlling for sex or ODD, the most common co-occurring disorder to ADHD, or lowering the HI and IA thresholds altered the stability of classified ADHD significantly from age 3 to 8 years.Our study has important strengths in the population-based cohort design and the use of a parent diagnostic interview when the children were 3 years, but it also has limitations. There were selection biases due to attrition in MoBa and the ADHD-study , 38, andOur findings from this population study, could suggest that age 3 years may be too early to apply the ADHD diagnostic symptom criteria, especially if one requires parent–teacher agreement. The reduction in parent-reported HI symptoms was large from preschool to school age. Therefore, clinicians should exercise caution in communicating concern about HI symptoms in preschool children, even when this information is provided in a diagnostic interview. The low reports of ADHD symptoms by teachers and low stability from age 3 to 8 years, may be related to preschool teachers perhaps not being trained in observing symptoms. However, the utility of preschool teacher-reported ADHD ratings should be investigated in a clinical study. Future studies should consider educating participating teachers on ADHD symptoms and investigate whether this will increase predictive value of their ratings, and the agreement between informants. Considering the void in the literature, with only three previous studies examining the validity of HI and IA symptoms in preschool children , 30, 32,Supplementary file1 (DOCX 15 KB)Below is the link to the electronic supplementary material.