The neurobiological profile of girls with ADHD

The global prevalence of attention deficit hyperactivity disorder in children and adolescents: An umbrella review of meta-analyses

BACKGROUND

Emerging epidemiological data suggest that hundreds of primary studies have examined the prevalence of ADHD in children and adolescents and dozens of systematic view and meta-analyses studies have been conducted on the subject. The purpose of this umbrella review is to provide a robust synthesis of evidence from these systematic reviews and meta-analyses.

METHODS

We systematically searched PubMed, Web of Science, PsychINFO, and Scopus to find pertinent studies. The study was preregistered with PROSPERO (CRD42023389704). The quality of the studies was assessed using a Measurement Tool to Assess Systematic Reviews (AMSTAR). Prevalence estimates from the included studies were pooled using invariance variance weighted random-effect meta-analysis.

RESULTS

Thirteen meta-analytic systematic reviews (588 primary studies) with 3,277,590 participants were included in the final analysis. A random effect meta-analysis of these studies showed that the global prevalence of ADHD in children and adolescents was 8.0 % (95%CI 6.0-10 %). The prevalence estimate was twice higher in boys (10 %) compared to girls (5 %). Of the three subtypes of ADHD, the inattentive type of ADHD (ADHD-I) was found to be the most common type of ADHD followed by the hyperactive (ADHD-HI) and the combined types (ADHD-C).

CONCLUSION

Findings from our compressive umbrella review suggest that ADHD is highly prevalent in children and adolescents with boys twice more likely to experience the disorder than girls. Our results underpin that priority should be given to preventing, early identifying, and treating ADHD in children and adolescents.

Clinical characteristics, neuroimaging findings, and neuropsychological functioning in attention-deficit hyperactivity disorder: Sex differences

Recent clinical studies, in both children/adolescents and adults, have shown the extreme neuropsychological heterogeneity of attention-deficit hyperactivity disorder (ADHD): specific neuropsychological deficits have been found only in a minority of individuals, with no direct correlation between discrete cognitive performances and the trajectory of clinical symptoms. Deficits in specific neuropsychological functions may be common in ADHD, but nevertheless no cognitive or neuropsychological profile may fully explain the disorder. Sex differences in the ADHD presentation, both at a neuropsychological and clinical level, also contribute to this clinical and neuropsychological heterogeneity. At a neuropsychological level, females with ADHD may show greater working memory problems, poorer vocabulary skills and worse visual spatial reasoning. Structural and functional imaging study also show discrete differences across sex; however, the great majority of clinical studies mainly or exclusively include male participants with insufficient data to draw firm conclusions on sex differences within the disorder. Here, we report the recent literature data, discussing still open research questions about the clinical presentation, neuroimaging findings, and neuropsychological functioning in ADHD with a focus on the impact of sex differences-a deeper insight in these unresolved issues may have relevant clinical and therapeutic implications for tailored, effective, and long-lasting interventions.

The impact of micronutrient supplementation in alcohol-exposed pregnancies on reaction time responses of preschoolers in Ukraine

The potential of micronutrients to ameliorate the impact of prenatal alcohol exposure (PAE) on attentional regulation skills was explored in a randomized clinical trial conducted in Ukraine. Women who differed in prenatal alcohol use were recruited during pregnancy and assigned to one of three groups [No study-provided supplements, Multivitamin/Mineral Supplement (MVM), or MVM plus Choline]. Their offspring were seen in the preschool period and a reaction time task was administered. Participants were asked to press a response button as quickly as possible as 30 stimuli from the same category (animals) were presented consecutively and then followed by six stimuli from a novel category (vehicles). Number correct, mean latency of the response over trials, and variability in the latency were analyzed separately by sex. During the initial animal trials, boys whose mothers received MVM during pregnancy had more correct responses and reduced response latency compared to boys whose mothers had no MVM treatment. During vehicle trials, maternal choline supplementation was associated with increased response speed in males without a PAE history. Females receiving supplements did not show the same benefits from micronutrient supplementation and were more adversely impacted by prenatal alcohol exposure. Relationships between maternal levels of choline, betaine, and dimethylglycine (DMG) and task performance were also assessed. Although no effects were found for choline after adjusting for multiple comparisons, lower baseline DMG level was associated with greater accuracy and shorter latency of responses in the initial animal trials and shorter latency in the vehicle trials in female preschoolers. Level of betaine in Trimester 3 was associated with reduced variability in the latency of male responses during the animal trials. Maternal micronutrient supplementation in pregnancy appears to improve preschool reaction time performance, but the effects varied as a function of sex and PAE exposure status.

Inattention, hyperactivity/impulsivity, and mathematics: Exploring gender differences in a nonclinical sample

In this study, we considered two subscales of attention problem (AP) behaviour, inattentiveness and hyperactivity/impulsivity, as latent traits, extreme values of which indicate attention deficit hyperactivity disorder (ADHD). We examined gender differences in these traits in a community sample of Russian schoolchildren and estimated the extent to which the association of AP behaviour and math achievement varied for boys and girls. The data from a three-wave longitudinal study of math achievement of 958 children (49 % girls) were used, and growth in math achievement was estimated. The levels of inattentiveness and hyperactivity/impulsivity of each child were measured based on teachers' responses using the Behaviour Rating Scale (BRS). The results demonstrated that inattentiveness had a negative association with math achievement, while hyperactivity/impulsivity was positively associated with math achievement when inattentiveness was controlled for. Inattentiveness was negatively associated with math achievement in both boys and girls. However, the size of this association decreased over time for boys, so the gap between boys with high inattentiveness and low inattentiveness decreased from grade 1 to grade 2. Meanwhile, for girls, the association between inattentiveness and math remained stable, so the gap between girls with high inattentiveness and girls with low inattentiveness did not change.

Early-term elective Caesarean sections did not increase the risk of behavioural problems at six to eight years of age

AIM

Our aim was to explore the under-researched associations between an elective Caesarean section (C-section) at early-term or full-term gestation and behaviour at 6-8 years of age.

METHODS

We identified 1220 eligible children born by elective C-sections at Danish hospital from 2009 to 2011. Their mothers were randomised to elective C-sections at either 38+3 (early-term) or 39+3 (full-term) weeks of gestation. From December 2017 to August 2018, the parents completed the Strengths and Difficulties Questionnaire. The results were adjusted for maternal education, parity and the child's sex.

RESULTS

Of the 574 (45%) children followed up, 288 were delivered early-term and 286 were delivered full-term. The groups had similar baseline characteristics. There were no differences in the total difficulties score, subscale scores or the risk of being classified as having a possible or probable psychiatric disorder. Early-term boys had a lower risk of being classified as having a possible or probable psychiatric disorder and early-term girls had higher risk, but the results were not statistically significant.

CONCLUSION

We found no difference in behaviour at 6-8 years of age between children born by elective C-section at early- versus full-term gestation.

Can the Child Behavior Checklist (CBCL) help characterize the types of psychopathologic conditions driving child psychiatry referrals?

Background:

Little is known about the scope of problems driving referrals to child and adolescent psychiatry services. Identifying the full range of mental disorders affecting a particular child can help triage the child to a clinician with the appropriate level of expertise. The Child Behavior Checklist (CBCL) is an easy-to-use assessment tool that may provide invaluable information regarding the severity of the presenting complaints and also aid in the referral process.

Objective:

To assess the utility of the CBCL to gain insights into the type of clinical problems driving referrals of youth to an outpatient pediatric psychiatry clinic.

Method:

The sample consisted of 418 newly referred youth 4-18 years of age of both sexes. Parents completed the CBCL assessing psychopathology and competence. Rates of patients with elevated T-scores on each scale were calculated for the whole group and stratified by sex and age (≤12 versus >12).

Results:

The CBCL identified high rates of psychopathology affecting referred youth. It also provided information on the type of suspected disorders affecting a particular child as well as their severity, critical information to guide likely differing clinical needs and therapeutic approaches. It also helped identify a high number of youth affected with multiple psychopathological conditions, likely to require a high level of clinical attention. Overall, males were significantly more impaired than females but there were no major differences between children and adolescents.

Conclusions:

The CBCL can aid in the identification of individual and comorbid mental disorders affecting youth seeking mental health services by providing specific information about the presence and the severity of specific suspected disorder. These findings have implications for prioritizing scarce resources in child mental health and for improved consideration of the complexity of clinical presentations to pediatric psychiatry programs of any type.

Sex Differences in the Meaning of Parent and Teacher Ratings of ADHD Behaviors: An Observational Study

Objective: To test explanations for the underrecognition of female ADHD by examining differences in adult ratings of boys and girls matched for levels of directly observed ADHD behaviors. Method: In a secondary analysis of a population-based sample, 3- to 4-year-olds (n = 153, 79 male) and 8- to 9-year-olds (n = 144, 75 male) were grouped according to levels of directly observed ADHD behaviors (low/moderate/high). Groups were then compared with parent/teacher ADHD ratings. Results: There were no sex differences in levels of directly observed ADHD behaviors within groups. For preschoolers, parents' ratings of males, but not females, significantly increased across groups-mirroring levels of observed behaviors. For older children, both parent and teacher mean ratings were significantly higher for males than females across groups. Conclusion: Identified differences in adult ratings of males and females matched for directly observed behaviors may contribute to understanding the substantial ADHD underrecognition in females.

The Montgomery and Åsberg Depression Rating Scale - self-assessment for use in adolescents: an evaluation of psychometric and diagnostic accuracy

Background: The Montgomery-Åsberg Depression Rating Scale - Self Assessment (MADRS-S) is used to assess symptom severity in major depressive disorder (MDD) among adolescents, but its psychometric properties and diagnostic accuracy are unclear.Aim: The aim of this study was to explore psychometric properties, including diagnostic accuracy, of the MADRS-S in adolescent psychiatric outpatients.Method: Adolescent psychiatric outpatients (N = 105, mean age 16 years, 46 boys) completed the MADRS-S and were interviewed using the Kiddie Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS).Results: In principal component analysis, two components with eigenvalues of 4.6 and 1.3 explained 51.1% and 14.4% of the variance, respectively. On the first component loaded items assessing Mood, Feelings of unease, Appetite, Initiative, Pessimism, and Zest for life. On the second component loaded items assessing Sleep, Ability to concentrate, and Emotional involvement. Cronbach's alpha (internal consistency) for all items was 0.87. Spearman's rho was 0.68 for concurrent validity (correlation between total MADRS-S-score and K-SADS MDD severity score). In receiver-operating characteristic analysis, the area under the curve was 0.86 (95% confidence interval 0.78-0.93, p < .001). For all the participants, the highest combined sensitivity and specificity were reached using cut-offs of 15 and 16 (sensitivity 0.82, specificity 0.86). Optimizing sensitivity for MDD, with specificity still ≥0.5, cut off for all was 9, for boys 7 and for girls 10.Conclusion: Psychometric properties of MADRS-S showed good reliability and validity as well as satisfying diagnostic accuracy, indicating good to excellent properties for MDD screening of adolescent psychiatric patients.

Reduced striatal GABA in unmedicated children with ADHD at 7T

Attention-deficit hyperactive disorder (ADHD) is characterized by inattention and increased impulsive and hypermotoric behaviors.Despite the high prevalence and impact of ADHD, little is known about the underlying neurophysiology of ADHD. The main inhibitory and excitatory neurotransmitters γ-aminobutyric acid (GABA) and glutamate are receiving increased attention in ADHD and can be measured using Magnetic Resonance Spectroscopy (MRS). However, MRS studies in ADHD are limited. We measured GABA and glutamate in young unmedicated participants, utilizing high magnetic field strength. Fifty unmedicated children (26 with ADHD, 24 controls) aged 5-9 years completed MRS at 7T and behavioral testing. GABA and glutamate were measured in dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), premotor cortex (PMC), and striatum, and estimated using LCModel. Children with ADHD showed poorer inhibitory control and significantly reduced GABA/Cr in the striatum, but not in ACC, DLPFC, or PMC regions. There were no significant group differences for Glu/Cr levels, or correlations with behavioral manifestations of ADHD. The primary finding of this study is a reduction of striatal GABA levels in unmedicated children with ADHD at 7T. These findings provide guidance for future studies or interventions. Reduced striatal GABA may be a marker for specific GABA-related treatment for ADHD.

The Effects of Physical Exercise on Functional Outcomes in the Treatment of ADHD: A Meta-Analysis

Objective: An increasing number of studies suggest possible beneficial effects of exercise in alleviating ADHD functional outcomes. The current study provides a quantitative meta-analysis of the available studies investigating this relationship. Method: Studies reporting on the effects of physical exercise on motor skills and executive functions in children with ADHD were identified through Cochrane, PsycInfo, PubMed, Web of Science databases. Ten publications were selected. Random-effects model was used to calculate effect sizes. Results: There was a significant effect of exercise on ADHD functional outcomes (g = 0.627). Longer exercise intervention duration was consistently associated with larger effect sizes. Effect sizes were not related to exercise intensity, mean age of participants, or gender distribution. Conclusion: Results suggest that exercise has a modest positive impact on ADHD functional outcomes, such as executive functions and motor skills, with longer interventions yielding better results.

Increased mirror overflow movements in ADHD are associated with altered EEG alpha/beta band desynchronization

Children with ADHD show developmentally abnormal levels of mirror overflow-unintentional movements occurring symmetrically opposite of intentional movements. Because mirror overflow correlates with ADHD behavioral symptoms, the study of disinhibition in motor control may shed light on physiologic mechanisms underlying impaired behavioral/cognitive control. This is a case-controlled study of EEG recording from 25 children with ADHD and 25 typically developing (TD) controls performing unilateral sequential finger tapping, with overflow movements measured using electronic goniometers. Consistent with previously published findings, children with ADHD showed increased mirror overflow as compared with TD peers. EEG findings revealed less lateralized alpha modulation (event-related desynchronization; ERD) and decreased magnitude of beta ERD in ADHD; both alpha and beta ERD reflect cortical activation. Moderation analysis revealed a significant association between beta ERD and overflow, independent of diagnosis; and an equivocal (p = .08) effect of diagnosis on the relationship between alpha ERD and overflow, with a significant effect in children with ADHD but not TD children. These results suggest two mechanisms involved with mirror overflow: one reflected in beta ipsilateral to the intentional movement and relevant to both children with ADHD and controls, and the other seemingly more specific to ADHD (alpha, contralateral to movement).

Executive Functions in Girls With and Without Childhood ADHD Followed Through Emerging Adulthood: Developmental Trajectories

Using an all-female sample, we examined trajectories of executive functioning (EF) performance from childhood through emerging adulthood-and their prediction of key emerging-adult outcomes. One hundred forty girls carefully diagnosed with attention deficit/hyperactivity disorder (ADHD) and 88 matched comparison girls were administered EF measurements assessing global EF, response inhibition, and verbal working memory during childhood (M age = 9.5 years), adolescence (M age = 14.1 years), the earliest years of adulthood (M age = 19.6 years), and the end of emerging adulthood (M age = 25.6 years). Retention rates were excellent. Hierarchical linear modeling was used to estimate growth curves for each EF measure. The linear EF slopes were then used to explore how changes in EF interacted with each participant's persistence/remission of ADHD over time to influence behavioral, emotional, and academic impairment in emerging adulthood. Although all women experienced absolute improvements in EF performance across time, women with histories of ADHD consistently lagged behind comparison women, even if their ADHD symptoms had remitted by early adulthood. However, EF performance over time did not significantly influence the link between ADHD status and (a) maternal reports of associated behavioral and emotional impairment or (b) objective measures of academic achievement. These findings indicate that EF deficits should be considered when developing and implementing treatments for ADHD through emerging adulthood. Future research should be aimed at understanding the mechanisms behind these observed trajectory differences.

Towards interpretable machine learning models for diagnosis aid: A case study on attention deficit/hyperactivity disorder

Attention Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder that has heavy consequences on a child's wellbeing, especially in the academic, psychological and relational planes. The current evaluation of the disorder is supported by clinical assessment and written tests. A definitive diagnosis is usually made based on the DSM-V criteria. There is a lot of ongoing research on ADHD, in order to determine the neurophysiological basis of the disorder and to reach a more objective diagnosis. The advent of Machine Learning (ML) opens up promising prospects for the development of systems able to predict a diagnosis from phenotypic and neuroimaging data. This was the reason why the ADHD-200 contest was launched a few years ago. Based on the publicly available ADHD-200 collection, participants were challenged to predict ADHD with the best possible predictive accuracy. In the present work, we propose instead a ML methodology which primarily places importance on the explanatory power of a model. Such an approach is intended to achieve a fair trade-off between the needs of performance and interpretability expected from medical diagnosis aid systems. We applied our methodology on a data sample extracted from the ADHD-200 collection, through the development of decision trees which are valued for their readability. Our analysis indicates the relevance of the limbic system for the diagnosis of the disorder. Moreover, while providing explanations that make sense, the resulting decision tree performs favorably given the recent results reported in the literature.

Suicidal ideation in adult ADHD: Gender difference with a specific psychopathological profile

OBJECTIVE

To investigate suicidal ideation (SI) in patients with adult ADHD (aADHD), and its association with gender and psychopathology.

METHODS

Case-control study with 206 participants (patients = 103/healthy controls = 103; matched on gender, age, and education). SI was assessed by the Beck-I Depression-Inventory. The Conners' Adult ADHD Rating Scale (CAARS) was used to characterize the ADHD symptom-domains.

RESULTS

Compared to controls, the likelihood of SI was significantly higher in females with ADHD (odds ratio[OR] = 25.0 (95%CI:2.98-200.0); the difference was not significant in males (OR = 2.09 (95%CI:0.75-5.81). In females, "Problems with Self-Concept" scores on the CAARS showed the closest association with SI (OR = 5.60,95%CI:2.34-13.41]), while in males it was "Impulsivity" scores (OR = 3.01,95%CI:1.50-6.06).

CONCLUSION

Our findings extend previously described transdiagnostic associations of specific psychopathological risk factors to aADHD, including problems with self-concept and impulsivity, which are robustly associated with suicidality across diagnostic boundaries. In addition, they indicate that these associations exhibit pronounced gender-specificity in aADHD.

Attention and Executive Function in Children Diagnosed with Attention Deficit Hyperactivity Disorder and Comorbid Disorders

OBJECTIVE

The goal of this study was to examine the relationship between comorbid disorders and executive function (EF) in children diagnosed with Attention Deficit/Hyperactivity Disorder (ADHD).

METHODS

Three hundred and fifty-five, 6-12 year old children clinically diagnosed with ADHD were included in the study. Comorbid anxiety disorders, Oppositional Defiant Disorder (ODD) and Conduct Disorder (CD) were examined. The EF domains were assessed using the Conners' Continuous Performance Test (CPT), Wisconsin Card Sorting Test (WCST), Tower of London (ToL), Finger Windows (FW) and Self Ordered Pointing Test (SOPT).

RESULTS

The findings indicate that children with comorbid anxiety disorders performed worse in domains measured by CPT and prior to controlling for age and sex, by FW. However, once sex was controlled for the results for FW were no longer significant. Children with CD obtained lower scores on WCST. Furthermore, a significant sex by CD interaction was observed.

CONCLUSION

These results indicate that comorbid disorders should be carefully examined as they play a significant role in EF performance and subsequently in day-to-day functioning of children with ADHD.

Abnormal brainstem auditory response in young females with ADHD

Studies have shown that the auditory brainstem response (ABR) is often affected in neurodevelopmental disorders. The aim of this study is to investigate possible differences in ABR between young females with ADHD compared to control subjects. This study focuses on young females, age 7-17 with ADHD, comparing the ABR of 43 young females with ADHD to 21 age- and gender-matched control subjects. Young females with ADHD have a significantly different ABR in a region between cochlear nucleus and superior olivary complex as well as in the thalamic region compared to control subjects. These data indicate specific differences in ABR between girls with ADHD compared to female controls.

Grey matter volume differences associated with gender in children with attention-deficit/hyperactivity disorder: A voxel-based morphometry study

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We studied gender effect on grey matter volumes in children with ADHD.

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A gender-by-diagnosis interaction was found in the ventral Anterior Cingulate Gyrus.

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This finding may underlie emotion dysregulation symptoms in ADHD.

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Contribute to differences in symptoms profiles between boys and girls with ADHD.

Female participants have been underrepresented in previous structural magnetic resonance imaging reports on attention-deficit/hyperactivity disorder (ADHD). In this study, we used optimized voxel-based morphometry to examine grey matter volumes in a sample of 33 never-medicated children with combined-type ADHD and 27 typically developing (TD) children. We found a gender-by-diagnosis interaction effect in the ventral anterior cingulate cortex (ACC), whereby boys with ADHD exhibited reduced volumes compared with TD boys, while girls with ADHD showed increased volumes when compared with TD girls. Considering the key role played by the ventral ACC in emotional regulation, we discuss the potential contribution of these alterations to gender-specific symptoms’ profiles in ADHD.

Parent ratings of executive function in young preschool children with symptoms of attention-deficit/-hyperactivity disorder

BACKGROUND

Recent research has demonstrated that deficits in basic, self-regulatory processes, or executive function (EF), may be related to symptoms of attention-deficit/hyperactivity disorder (ADHD) already during the preschool period. As the majority of studies investigating these relations in young children have been based primarily on clinically administered tests, it is not clear how early symptoms of ADHD may be related to observations of EF in an everyday context. The preschool version of the Behavior Rating Inventory of Executive Function (BRIEF-P) was developed to provide information about EF through observable, behavioral manifestations of self-regulation, and is the most commonly used rating scale for EF assessment in children.

METHODS

Relations between symptoms of ADHD reported in the Preschool Age Psychiatric Assessment interview (PAPA), and EF as measured by the BRIEF-P (parent form), were investigated in a large, nonreferred sample of preschool children (37-47 months, n = 1134) recruited from the Norwegian Mother and Child Cohort Study (MoBa) at the Norwegian Institute of Public Health. The inventory's discriminative ability was examined in a subsample consisting of children who met the diagnostic criteria for either ADHD, oppositional defiant disorder (ODD) or anxiety disorder, and typically developing controls (n = 308). The four groups were also compared with regard to patterns of EF difficulties reported in the BRIEF-P.

RESULTS

Of the five BRIEF-P subscales, Inhibit and Working Memory were the two most closely related to ADHD symptoms, together explaining 38.5% of the variance in PAPA symptom ratings. Based on their scores on the Inhibit and Working Memory subscales (combined), 86.4% of the children in the ADHD and TD groups were correctly classified. ADHD symptoms were associated with more severe difficulties across EF domains, and a different EF profile in comparison to children with other symptoms (anxiety, ODD) and to typically developing controls.

CONCLUSIONS

Early symptoms of ADHD were linked to parent-reported difficulties primarily within inhibition and working memory, suggesting that deficiencies within these two EF domains characterize early forms of ADHD. Our findings support the clinical utility of the BRIEF-P as a measure of EF in young preschool children with symptoms of ADHD.

Sustained impact of inattention and hyperactivity-impulsivity on peer problems: mediating roles of prosocial skills and conduct problems in a community sample of children

This prospective 2-year longitudinal study tested whether inattentive and hyperactive/impulsive symptom dimensions predicted future peer problems, when accounting for concurrent conduct problems and prosocial skills. A community sample of 492 children (49 % female) who ranged in age from 6 to 10 years (M = 8.6, SD = .93) was recruited. Teacher reports of children's inattention, and hyperactivity/impulsivity symptoms, conduct problems, prosocial skills and peer problems were collected in two consecutive school years. Elevated inattention and hyperactivity/impulsivity in Year-1 predicted greater peer problems in Year-2. Conduct problems in the first and second years of the study were associated with more peer problems, and explained a portion of the relationship between inattention and hyperactivity/impulsivity with peer problems. However, prosocial skills were associated with fewer peer problems in children with elevated inattention and hyperactivity/impulsivity. Inattention and hyperactivity/impulsivity have negative effects on children's peer functioning after 1-year, but concurrent conduct problems and prosocial skills have important and opposing impacts on these associations.

Charting early trajectories of executive control with the shape school

Despite acknowledgement of the importance of executive control for learning and behavior, there is a dearth of research charting its developmental trajectory as it unfolds against the background of children's sociofamilial milieus. Using a prospective, cohort-sequential design, this study describes growth trajectories for inhibitory control and cognitive flexibility across the preschool period in relation to child sex and sociofamilial resources. At ages 3, 3.75, 4.5, and 5.25 years, children (N = 388) from a broad range of social backgrounds were assessed using the Shape School, a graduated measure of executive control incorporating baseline, inhibitory control, and cognitive flexibility conditions. Measures of children's proximal access to learning resources and social network supports were collected at study entry. Findings revealed substantial gains in accuracy and speed for all Shape School conditions, these gains being particularly accelerated between ages 3 and 3.75 years. Improvements in inhibitory control were more rapid than those in flexible switching. Age-related differences in error and self-correction patterns on the Shape School also suggest qualitative changes in the underlying processes supporting executive performance across early childhood. Children from homes with fewer learning resources showed a subtle lag in inhibition and cognitive flexibility performance that persisted at kindergarten entry age, despite exhibiting gradual catch up to their more advantaged peers for the nonexecutive, baseline task condition. The study provides a unique characterization of the early developmental pathways for inhibitory control and cognitive flexibility and highlights the critical role of stimulating early educational resources for shaping the dynamic ontogeny of executive control.

Early fetal binge alcohol exposure predicts high behavioral symptom scores in 5.5-year-old children

BACKGROUND

Fetal binge alcohol exposure has been associated with neurobehavioral and cognitive symptoms. This study explored whether binge drinking mainly before recognition of pregnancy predicted high symptom scores on the Strengths and Difficulties Questionnaire (SDQ) in 5.5-year-old children.

METHODS

In a population-based, longitudinal study representative of pregnant women in Oslo, Norway, questionnaires were answered at 17 and 30 weeks of pregnancy, 6 months after term, and at child age 5.5 years (n = 1,116, constituting 66% of the original cohort). Logistic regression analyses identified factors predicting high SDQ scores, and multiple regression analyses identified direct effects on the SDQ Total.

RESULTS

Binge exposure (≥5 standard units per occasion [SUpo]) during pregnancy week 0 to 6, that is, 0 to 4 weeks after conception, predicted scores in the Abnormal and Borderline range on the SDQ in 5.5-year-olds, after adjusting for other confounding variables. Very early binge exposure less often than once a week predicted high symptom scores on the SDQ Total (p = 0.05) and Hyperactivity/Inattention (significant), while exposure at least once a week demonstrated a 3- to 5-fold significant increase in high symptom scores on Total, Emotional, and Conduct problems. Reporting ≥8 SUpo had stronger predictive power than reporting 5 to 7 SUpo. The results were not explained by participants reporting major lifetime depression. Other predictive factors, although weaker, were maternal symptoms of depression and anxiety during the child's infancy. High education (mother and father), high income (maternal partner), higher child birth weight, and child female sex reduced the likelihood of high SDQ symptom scores. Path analysis demonstrated early binge exposure to have a direct effect on the SDQ Total score.

CONCLUSIONS

Binge drinking up to 4 weeks after conception had a strong and direct predictive effect on SDQ symptom scores in 5.5-year-olds. These results strongly support the advice to avoid binge drinking when planning pregnancy.

Persisting primitive reflexes in medication-naïve girls with attention-deficit and hyperactivity disorder

BACKGROUND AND OBJECTIVES

Recent and historical findings suggest that later-developed functions during brain ontogenesis related to higher levels of cognitive and motor integration tend to replace the older, more primitive, ones, and the persistence of the older functions may be linked to specific neuropsychiatric disorders. Currently, there is growing evidence to suggest that persisting primitive reflexes may be related to developmental and neurodegenerative disorders. Preliminary data also suggest that persisting primitive reflexes may be specifically linked to attention-deficit and hyperactivity disorder (ADHD).

METHODS

In the study reported here, we tested to what extent the persisting primitive asymmetric tonic neck reflex and symmetric tonic neck reflex are related to ADHD symptoms measured by Conners' Parent Questionnaire in 35 medication-naïve girls of school age (8-11 years) with ADHD. The results were compared with those of a control group of 30 girls of the same age.

RESULTS

This study showed that persisting primitive reflexes are closely linked to ADHD symptoms.

CONCLUSION

The data suggest that ADHD symptoms may be linked to more primitive neural mechanisms interfering with higher brain functions due to insufficiently developed cognitive and motor integration.

Network, anatomical, and non-imaging measures for the prediction of ADHD diagnosis in individual subjects

Brain imaging methods have long held promise as diagnostic aids for neuropsychiatric conditions with complex behavioral phenotypes such as Attention-Deficit/Hyperactivity Disorder. This promise has largely been unrealized, at least partly due to the heterogeneity of clinical populations and the small sample size of many studies. A large, multi-center dataset provided by the ADHD-200 Consortium affords new opportunities to test methods for individual diagnosis based on MRI-observable structural brain attributes and functional interactions observable from resting-state fMRI. In this study, we systematically calculated a large set of standard and new quantitative markers from individual subject datasets. These features (>12,000 per subject) consisted of local anatomical attributes such as cortical thickness and structure volumes, and both local and global resting-state network measures. Three methods were used to compute graphs representing interdependencies between activations in different brain areas, and a full set of network features was derived from each. Of these, features derived from the inverse of the time series covariance matrix, under an L1-norm regularization penalty, proved most powerful. Anatomical and network feature sets were used individually, and combined with non-imaging phenotypic features from each subject. Machine learning algorithms were used to rank attributes, and performance was assessed under cross-validation and on a separate test set of 168 subjects for a variety of feature set combinations. While non-imaging features gave highest performance in cross-validation, the addition of imaging features in sufficient numbers led to improved generalization to new data. Stratification by gender also proved to be a fruitful strategy to improve classifier performance. We describe the overall approach used, compare the predictive power of different classes of features, and describe the most impactful features in relation to the current literature.

Variable sleep schedules and outcomes in children with psychopathological problems: preliminary observations

BACKGROUND

Night-to-night variability in sleep of children with attention deficit hyperactivity disorder (ADHD) may be a mediator of behavioral phenotype. We examined the potential association between alertness, sleep, and eating behaviors in children with ADHD and comorbid problems.

METHODS

Sleep was monitored by actigraphy for 7 days. Questionnaires were used to assess sleep complaints, habits and food patterns by parental report, and sleep complaints and sleepiness by child report.

RESULTS

The group comprised 18 children, including 15 boys, aged 9.4 ± 1.7 years, 88.9% Caucasian, who took one or multiple medications. Children slept on average for 6 hours and 58 minutes with a variability of 1 hour 3 minutes relative to the mean, and their sleepiness scores were highly variable from day to day. Most children had a normal body mass index (BMI). Sleepiness and BMI were associated with sleep schedules and food patterns, such that they accounted for 76% of variance, predominantly by the association of BMI with mean wake after sleep onset and by bedtime sleepiness, with wake after sleep onset variability. Similarly, 97% of variance was shared with eating behaviors, such as desserts and snacks, and fast food meals were associated with morning sleepiness.

CONCLUSION

Disrupted sleep and sleepiness appears to favor unhealthy food patterns and may place children with ADHD at increased risk for obesity.

Comprehensive examination of frontal regions in boys and girls with attention-deficit/hyperactivity disorder

The current study examined regional frontal lobe volumes based on functionally relevant subdivisions in contemporaneously recruited samples of boys and girls with and without attention-deficit/hyperactivity disorder (ADHD). Forty-four boys (21 ADHD, 23 control) and 42 girls (21 ADHD, 21 control), ages 8-13 years, participated. Sulcal-gyral landmarks were used to manually delimit functionally relevant regions within the frontal lobe: primary motor cortex, anterior cingulate, deep white matter, premotor regions [supplementary motor complex (SMC), frontal eye field, lateral premotor cortex (LPM)], and prefrontal cortex (PFC) regions [medial PFC, dorsolateral PFC (DLPFC), inferior PFC, lateral orbitofrontal cortex (OFC), and medial OFC]. Compared to sex-matched controls, boys and girls with ADHD showed reduced volumes (gray and white matter) in the left SMC. Conversely, girls (but not boys) with ADHD showed reduced gray matter volume in left LPM; while boys (but not girls) with ADHD showed reduced white matter volume in left medial PFC. Reduced left SMC gray matter volumes predicted increased go/no-go commission rate in children with ADHD. Reduced left LPM gray matter volumes predicted increased go/no-go variability, but only among girls with ADHD. Results highlight different patterns of anomalous frontal lobe development among boys and girls with ADHD beyond that detected by measuring whole lobar volumes.

Differences in Performance of ADHD Children on a Visual and Auditory Continuous Performance Test according to IQ

OBJECTIVE

Continuous performance tests (CPTs) are frequently used in clinical practice to assess the attentiveness of ADHD children. Although most CPTs do not categorize T scores by intelligence, there is great diversity of opinion regarding the interrelation between intelligence and CPT performance. This study aimed to determine if ADHD children with superior IQs would perform better than ADHD children with average IQs. Additionally, we aimed to examine the need for CPTs' to categorize according to IQ.

METHODS

Participants were 326 outpatients, aged 5-15 years, diagnosed with ADHD. All participants completed the Wechsler Intelligence Scale for Children-Revised and a CPT. After excluding those who meet exclusion criteria, we had 266 patients for our analysis.

RESULTS

The "Highly Intelligent Group" (HIG), patients with IQs 120 and above, performed superiorly to the "Normally Intelligent Group" (NIG) patients, with IQs between 70 and 120, with regard to omission and commission errors on the visual-auditory CPT, even after controlling for age and gender. The HIG had higher ratios of subjects with T scores <65 on the visual and auditory CPT variables than the NIG did.

CONCLUSION

The results of this study suggest this CPT is not sensitive for discerning ADHD in children with superior IQs; thus, there is a need to standardize the variables based on IQ, as well as on age and gender. Moreover, clinicians need to pay attention to the effect of IQ in interpreting CPT scores; that is, a "normal" score does not rule out a diagnosis of ADHD.

Fronto-striatal underactivation during interference inhibition and attention allocation in grown up children with attention deficit/hyperactivity disorder and persistent symptoms

Attention deficit hyperactivity disorder (ADHD) in medication-naïve children has been associated with reduced activation in inferior/medial prefrontal, striatal and parieto-temporal cortices during inhibitory control and attention allocation. Functional magnetic resonance imaging (fMRI) studies in adult ADHD, however, have been inconsistent and confounded by medication-history and the need for a retrospective diagnosis of childhood ADHD. We used fMRI combined with a Simon task that measured interference inhibition and controlled for and co-measured attention allocation to compare brain function in 11 medication-naïve adults with persistent inattentive/hyperactive behaviours, followed up from childhood ADHD, and 15 age-matched controls. Despite comparable task performance, patients showed reduced activation compared to controls in left orbital/medial frontal cortex and striatum during interference inhibition and in left lateral inferior/dorsolateral prefrontal cortex during attention allocation. Whole-brain regression analyses within patients showed a negative correlation between symptom severity and fronto-striatal, temporo-parietal and cerebellar brain activation. The findings demonstrate that the typical fronto-striatal dysfunction observed in children with ADHD during interference inhibition and attention allocation is also observed in adults grown up from childhood ADHD with persistent symptoms. Furthermore, they show that functional deficits in adult ADHD are not related to chronic stimulant medication given that this sample was medication-naive.

Methylphenidate normalizes fronto-striatal underactivation during interference inhibition in medication-naïve boys with attention-deficit hyperactivity disorder

Youth with attention deficit hyperactivity disorder (ADHD) have deficits in interference inhibition, which can be improved with the indirect catecholamine agonist methylphenidate (MPH). Functional magnetic resonance imaging was used to investigate the effects of a single dose of MPH on brain activation during interference inhibition in medication-naïve ADHD boys. Medication-naïve boys with ADHD were scanned twice, in a randomized, double-blind design, under either a single clinical dose of MPH or placebo, while performing a Simon task that measures interference inhibition and controls for the oddball effect of low-frequency appearance of incongruent trials. Brain activation was compared within patients under either drug condition. To test for potential normalization effects of MPH, brain activation in ADHD patients under either drug condition was compared with that of healthy age-matched comparison boys. During incongruent trials compared with congruent-oddball trials, boys with ADHD under placebo relative to controls showed reduced brain activation in typical areas of interference inhibition, including right inferior prefrontal cortex, left striatum and thalamus, mid-cingulate/supplementary motor area, and left superior temporal lobe. MPH relative to placebo upregulated brain activation in right inferior prefrontal and premotor cortices. Under the MPH condition, patients relative to controls no longer showed the reduced activation in right inferior prefrontal and striato-thalamic regions. Effect size comparison, furthermore, showed that these normalization effects were significant. MPH significantly normalized the fronto-striatal underfunctioning in ADHD patients relative to controls during interference inhibition, but did not affect medial frontal or temporal dysfunction. MPH therefore appears to have a region-specific upregulation effect on fronto-striatal activation.

Executive control and dimensions of problem behaviors in preschool children

BACKGROUND

Despite the widespread recognition of the importance of executive control (EC) in externalizing psychopathology, the relation between EC and problem behavior has not been well characterized, particularly in typically developing preschoolers.

METHOD

Using the sample, battery of laboratory tasks, and latent variable modeling methods described in Wiebe, Espy, and Charak (2008), systematic latent dimensions of parent-rated problem behavior, measured by integrating scales from developmental and clinical traditions, were determined empirically, and then were related to EC.

RESULTS

Substantial relations between EC and problem behaviors were revealed by extracting the common variance of interest and eliminating extraneous variance, which were robust to estimated child intelligence and differed somewhat in preschool boys and girls.

CONCLUSION

Preschool EC measured by laboratory tasks appears to tap abilities that strongly and robustly support broad control processes enabling behavioral regulation across cognitive and emotional domains.

Gender-specific association of the brain-derived neurotrophic factor gene with attention-deficit/hyperactivity disorder

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) is a complex neurodevelopmental disorder with a strong genetic component. Brain-derived neurotrophic factor (BDNF), which participates in the differentiation and survival of dopaminergic and noradrenergic neurons, could play a role in ADHD development. We aimed to explore the relationships between ADHD and BDNF gene polymorphism.

METHODS

We conducted a case-control analysis of 202 ADHD subjects and 159 controls, performed a transmission disequilibrium test on 151 trios, and compared the results of a continuous performance test (CPT) according to the genotype of the three single nucleotide polymorphisms (rs11030101, rs6265, rs16917204) in the BDNF gene.

RESULTS

In the case-control analysis, the AA genotype of the BDNF rs11030101 polymorphism was significantly associated with ADHD only in girls (p=0.024, odds ratio=3.00). The T-G-G haplotype was significantly less frequent (p=0.005) and A-G-G was more frequent (p=0.048) in girls with ADHD than in control girls (global p=0.027). A multivariate analysis of variance for commission errors on the CPT showed a significant main effect for the rs11030101 genotype (p=0.026) and an interaction effect of the rs11030101 genotype and gender (p=0.032) in ADHD probands.

CONCLUSION

These results provide preliminary evidence for a gender-specific association between BDNF and ADHD in the Korean population.

The ESSENCE in child psychiatry: Early Symptomatic Syndromes Eliciting Neurodevelopmental Clinical Examinations

Co-existence of disorders--including attention-deficit/hyperactivity disorder, oppositional defiant disorder, tic disorder, developmental coordination disorder, and autism spectrum disorder--and sharing of symptoms across disorders (sometimes referred to as comorbidity) is the rule rather than the exception in child psychiatry and developmental medicine. The acronym ESSENCE refers to Early Symptomatic Syndromes Eliciting Neurodevelopmental Clinical Examinations. It is a term I have coined to refer to the reality of children (and their parents) presenting in clinical settings with impairing child symptoms before age 3 (-5) years in the fields of (a) general development, (b) communication and language, (c) social inter-relatedness, (d) motor coordination, (e) attention, (f) activity, (g) behaviour, (h) mood, and/or (i) sleep. Children with major difficulties in one or more (usually several) of these fields, will be referred to and seen by health visitors, nurses, social workers, education specialists, pediatricians, GPs, speech and language therapists, child neurologists, child psychiatrists, psychologists, neurophysiologists, dentists, clinical geneticists, occupational therapists and physiotherapists, but, usually they will be seen only by one of these specialists, when they would have needed the input of two or more of the experts referred to. Major problems in at least one ESSENCE domain before age 5 years often signals major problems in the same or overlapping domains years later. There is no time to wait; something needs to be done, and that something is unlikely to be just in the area of speech and language, just in the area of autism or just in special education.

Neuropsychological profile of executive function in girls with attention-deficit/hyperactivity disorder

The majority of research on neurobehavioral functioning among children with Attention-Deficit/Hyperactivity Disorder (ADHD) is based on samples comprised primarily (or exclusively) of boys. Although functional impairment is well established, available research has yet to specify a neuropsychological profile distinct to girls with ADHD. The purpose of this study was to examine performance within four components of executive function (EF) in contemporaneously recruited samples of girls and boys with ADHD. Fifty-six children with ADHD (26 girls) and 90 controls (42 girls), ages 8-13, were administered neuropsychological tests emphasizing response inhibition, response preparation, working memory, and planning/shifting. There were no significant differences in age or SES between boys or girls with ADHD or their sex-matched controls; ADHD subtype distribution did not differ by sex. Compared with controls, children with ADHD showed significant deficits on all four EF components. Girls and boys with ADHD showed similar patterns of deficit on tasks involving response preparation and working memory; however, they manifested different patterns of executive dysfunction on tasks related to response inhibition and planning. Girls with ADHD showed elevated motor overflow, while boys with ADHD showed greater impairment during conscious, effortful response inhibition. Girls, but not boys with ADHD, showed impairment in planning. There were no differences between ADHD subtypes on any EF component. These findings highlight the importance of studying boys and girls separately (as well as together) when considering manifestations of executive dysfunction in ADHD.

The influences of environmental enrichment, cognitive enhancement, and physical exercise on brain development: can we alter the developmental trajectory of ADHD?

Attention-deficit/Hyperactivity Disorder (ADHD) is characterized by a pervasive pattern of developmentally inappropriate inattentive, impulsive and hyperactive behaviors that typically begin during the preschool years and often persist into adulthood. The most effective and widely used treatments for ADHD are medication and behavior modification. These empirically-supported interventions are generally successful in reducing ADHD symptoms, but treatment effects are rarely maintained beyond the active intervention. Because ADHD is now generally thought of as a chronic disorder that is often present well into adolescence and early adulthood, the need for continued treatment throughout the lifetime is both costly and problematic for a number of logistical reasons. Therefore, it would be highly beneficial if treatments would have lasting effects that remain after the intervention is terminated. This review examines the burgeoning literature on the underlying neural determinants of ADHD along with research demonstrating powerful influences of environmental factors on brain development and functioning. Based upon these largely distinct scientific literatures, we propose an approach that employs directed play and physical exercise to promote brain growth which, in turn, could lead to the development of potentially more enduring treatments for the disorder.

Reduced activation and inter-regional functional connectivity of fronto-striatal networks in adults with childhood Attention-Deficit Hyperactivity Disorder (ADHD) and persisting symptoms during tasks of motor inhibition and cognitive switching

Attention-Deficit Hyperactivity Disorder (ADHD) in children has been associated with fronto-striatal functional abnormalities during tasks of inhibitory control. In adults with ADHD, however, hardly any functional magnetic resonance imaging (fMRI) studies have investigated the neurofunctional correlates of the most compromised cognitive functions of motor response inhibition and no study has investigated cognitive flexibility. In this study we used fMRI to compare brain function and task-relevant inter-regional functional connectivity between 11 medication-naïve adults with persistent inattentive/hyperactive behaviours, followed up from childhood when they had been diagnosed with ADHD, and 14 age-matched healthy controls during a Stop and a cognitive Switch tasks. Whole-brain regression MR analyses were conducted within patients to correlate symptoms with brain activation. Despite comparable task performance, adults with childhood ADHD showed reduced activation compared to controls in bilateral inferior prefrontal cortex, caudate and thalamus during both tasks, as well as in left parietal lobe during the Switch task. Within patients, the severity of the behavioural symptoms was negatively correlated with more extensive activation of similar regions in fronto-striatal, parietal and cerebellar brain areas. In the Stop task, patients showed reduced inter-regional functional connectivity between right inferior fronto-frontal, fronto-striatal and fronto-parietal neural networks. The findings demonstrate that adults with childhood ADHD and persisting behavioural symptoms show strikingly similar patterns of fronto-striatal and parietal dysfunction to those observed in childhood ADHD during the same tasks of inhibitory control. This suggests that neuro-functional abnormalities in ADHD patients are likely to continue between childhood and early adulthood.

Self-regulation in ADHD: the role of error processing

Attention-deficit hyperactivity disorder (ADHD) is characterized by persistent and impairing developmentally inappropriate levels of inattention, hyperactivity, and impulsivity. Such behavioral dysregulation may be a consequence of deficits in self-monitoring or adaptive control, both of which are required for adaptive behavior. Processing of contextual demands, ongoing monitoring of one's behavior to evaluate whether it is appropriate for a particular situation, and adjusting behavior when it is suboptimal are components of self-regulation. This review examines and integrates the emerging literature on error-processing and adaptive control as components of self-regulation into the prominent etiological theories of ADHD. Available data on error-processing, as reflected in event-related potentials (ERN and Pe) and behavioral performance, suggest that both early error detection and later error-evaluation may be diminished in ADHD, thereby interfering with adaptive control processes. However, variability in results limit broad conclusions, particularly for early error detection. A range of methodological issues, including ERP parameters and sample and task characteristics, likely contribute to this variability, and recommendations for future work are presented. The emerging literature on error-processing and adaptive control informs etiological theories of ADHD in general and may provide a method for testing self-regulation models in particular.

Structural and functional brain imaging in adult attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a childhood disorder that persists into adulthood. Nevertheless, there are far fewer imaging studies in adult compared with childhood ADHD. Here we review the imaging literature on brain structure, function and structural and functional connectivity in adult ADHD, as well as the effects of psychostimulants on brain dysfunctions. Importantly, we discuss similarities and differences between these deficit findings and those in childhood ADHD to address the key question of continuity of brain abnormalities into adulthood. Findings show strikingly similar but more inconsistent abnormalities in adult ADHD in key childhood ADHD deficit areas of frontostriatal, temporoparietal and cerebellar regions, presumably due to highly prevalent confounding factors in adult ADHD of elevated rates of comorbidity and medication history.