Genetics of attention deficit hyperactivity disorder

The Prevalence of Risk Factors Among Children Diagnosed With Attention-Deficit/Hyperactivity Disorder, Aged 4-17 Years: A Cross-Sectional Study

INTRODUCTION

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder commonly observed in children. Although the etiology of ADHD is still unclear, many risk factors have been shown to increase the prevalence of ADHD, such as genetics, environmental factors, socioeconomic status, maternal smoking, and low birth weight.

AIM

The current cross-sectional study aimed to assess the prevalence of several risk factors associated with ADHD-diagnosed children aged 4-17 years using parent-reported data.

METHODS

An observational cross-section study was conducted between December 2022 and February 2023 using a self-constructed questionnaire that we sent to parents whose children were diagnosed with ADHD. The questionnaire included socioeconomic information (income, gender, parent education, number of children), child information (age, ADHD type, academic achievement), pregnancy and neonatal period (smoking status, gestation age, mode of delivery, child weight), and if there is a history of ADHD in the family.

RESULTS

A total of 306 parents responded to the questionnaire. The majority of our study population was males (77.8%). The combined type, which includes symptoms of both hyperactivity and inattention, represented 70% of the population in our study, which is higher than the inattention type (23%) and the hyperactivity type (6%). The prevalence of several risk factors known to be associated with ADHD, such as family income, parental education, complications during pregnancy, and the low birth weight of the child, were also reported.

CONCLUSION

To the best of our knowledge, this is the first study that examines the frequency of risk factors among children diagnosed with ADHD in Saudi Arabia. The study revealed that males are more likely to be diagnosed with ADHD than females. We also found that the combined type is the most diagnosed ADHD among children. Furthermore, there are no significant differences in the prevalence of the risk factors during the gestational or neonatal period among ADHD-diagnosed children. Therefore, a large-scale prospective study is needed to aid in evaluating the frequency and significance of various risk factors among diagnosed children.

Dissociable effects of positive feedback on the capture and inhibition of impulsive behavior in adolescents with ADHD versus typically developing adolescents

The present study investigated how enhancing motivation by delivering positive feedback (a smiley) after a successful trial could affect interference control in adolescents with Attention Deficit Hyperactivity Disorder (ADHD) and in their typically developing (TD) peers. By using a Simon task within the theoretical framework of the "activation-suppression" model, we were able to separately investigate the expression and the inhibition of impulsive motor behavior. The experiment included 19 adolescents with ADHD and 20 TD adolescents in order to explore whether data found in adolescents with ADHD were similar to those found in TD adolescents. Participants performed the Simon task in two conditions: a condition with feedback delivered after each successful trial and a condition with no feedback. The main findings were that increasing motivation by delivering positive feedback increased impulsive response in both groups of adolescents. It also improved the efficiency of impulsive motor action inhibition in adolescents with ADHD but deteriorated it in TD adolescents. We suggest that 1/increased motivation could lead adolescents to favor fast responses even if incorrect, and 2/the differential effect of feedback on the selective suppression of impulsive motor action in both groups could be due to different baseline DA levels.

Predictors of Attention Deficit Hyperactivity Disorder in Sri Lankan Children: A School Based Community Study

OBJECTIVE

To evaluate potential risk-factors of ADHD among primary school-children (PSC) in state schools in Colombo district of Sri Lanka.

METHOD

A case-control study was conducted with 73 cases and 264 controls selected randomly among 6 to 10-year-old PSC from Sinhala medium state schools in Colombo district. Primary care givers completed the SNAP-IV P/T-S scale to screen for ADHD and an interviewer-administered questionnaire on risk-factors. Children's diagnostic status was confirmed by a Consultant Child and Adolescent Psychiatrist based on DSM-5 criteria.

RESULTS

A binomial regression model identified male sex (aOR = 3.45; 95% CI [1.65, 7.18]), lower educational level of the mother (aOR = 2.99; 95% CI [1.31, 6.48]), birth weight <2,500 g (aOR = 2.83; 95% CI [1.17, 6.81]),a neonatal complications (aOR = 3.82; 95% CI [191, 7.65]) and child having witnessed verbal/emotional aggression between parents (aOR = 2.08; 95% CI [1.01, 4.27])as significant predictors of ADHD.

CONCLUSION

Primary prevention should focus on strengthening neonatal, maternal and child health services within the country.

Prevalence of ADHD in Primary School Children, in Colombo District, Sri Lanka

OBJECTIVE

To determine prevalence of ADHD among primary school children in Colombo district, Sri Lanka.

METHODS

A descriptive cross-sectional study was conducted among 1,125 primary school children aged 6 to 10 years in Sinhala medium state schools in Colombo district. Prevalence was assessed with validated Sinhala version of Swanson, Nolan, Pelham-IV (SNAP-IV-S) scale where primary care givers and class teachers were the respondents and diagnosis was confirmed by a Consultant Child and Adolescent Psychiatrist.

RESULTS

The mean age of the sample was 7.9 years (SD = 1.2) and largely males (n = 603, 56.6%). Overall prevalence of ADHD was 6.5% (95% CI [5.1, 8.1]) with combined as the commonest subtype. Prevalence was higher among males (9.6%) than females (2.9%) with a sex ratio of 1:3.8 and was highest in the 7 to 8 year old age group (7.4%-7.5%).

CONCLUSION

School based screening enabling early detection of ADHD and timely referral is the need of the hour.

[The Genetic Basis of ADHD - An Update]

The Genetic Basis of ADHD - An Update Abstract. Genetic risks play an important role in the etiology of attention-deficit/hyperactivity disorder (ADHD). This review presents the current state of knowledge concerning the genetic basis of the disorder. It discusses the results of twin- and family-based studies, linkage and association studies as well as recent findings resulting from Genome Wide Association Studies (GWAS). Furthermore, it elaborates on the relevance of polygenic risk scores, rare variants, and epigenetic alterations, especially in light of findings on genetic pleiotropy in the context of frequent psychiatric comorbidities in patients with ADHD.

Modulation of Spatial Memory Deficit and Hyperactivity in Dopamine Transporter Knockout Rats via α2A-Adrenoceptors

Attention deficit hyperactivity disorder (ADHD) is manifested by a specific set of behavioral deficits such as hyperactivity, impulsivity, and inattention. The dopamine neurotransmitter system is postulated to be involved in the pathogenesis of ADHD. Guanfacine, a selective α2A-adrenoceptor agonist, is prescribed for ADHD treatment. ADHD also is known to be associated with impairment of multiple aspects of cognition, including spatial memory, however, it remains unclear how modulation of the norepinephrine system can affect these deficits. Hyperdopaminergic dopamine transporter knockout (DAT-KO) rats are a valuable model for investigating ADHD. The DAT-KO rats are hyperactive and deficient in spatial working memory. This work aimed to evaluate the effects of noradrenergic drugs on the fulfillment of spatial cognitive tasks by DAT-KO rats. The rats were tested in the Hebb - Williams maze during training and following noradrenergic drugs administration. The efficiency of spatial orientation was assessed as to how fast the animal finds an optimal way to the goal box. Testing in a new maze configuration allowed us to evaluate the effects of drug administration after the acquisition of the task rules. The behavioral variables such as the distance traveled, the time to reach the goal box, and the time spent in the error zones were analyzed. It has been observed that α2A-adrenoceptor agonist Guanfacine (0.25 mg/kg) had only a minimal inhibitory effect on hyperactivity of DAT-KO rats in the maze but significantly ameliorated their perseverative pattern of activity and reduced the time spent in the error zones. In contrast, α2A-adrenoceptor antagonist Yohimbine, at the dose of 1 mg/kg, increased the distance traveled by DAT-KO rats and elevated the number of perseverative reactions and the time spent in the error zones. Guanfacine caused minimal effects in wild-type rats, while Yohimbine altered several parameters reflecting a detrimental effect on the performance in the maze. These data indicate that modulation of α2A-adrenoceptor activity potently affects both dopamine-dependent hyperactivity and cognitive dysfunctions. Similar mechanisms may be involved in the beneficial effects of Guanfacine on cognitive deficits in ADHD patients. This study further supports the translational potential of DAT-KO rats for testing new pharmacological drugs.

Shared alterations in resting-state brain connectivity in adults with attention-deficit/hyperactivity disorder and their unaffected first-degree relatives

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is a developmental condition that often persists into adulthood with extensive negative consequences on quality of life. Despite emerging evidence indicating the genetic basis of ADHD, investigations into the familial expression of latent neurocognitive traits remain limited.

METHODS

In a group of adult ADHD probands (n = 20), their unaffected first-degree relatives (n = 20) and typically developing control participants (n = 20), we assessed endophenotypic alterations in the default mode network (DMN) connectivity during resting-state functional magnetic resonance imaging in relation to cognitive performance and clinical symptoms. In an external validation step, we also examined the dimensional nature of this neurocognitive trait in a sample of unrelated healthy young adults (n = 100) from the Human Connectome Project (HCP).

RESULTS

The results illustrated reduced anti-correlations between the posterior cingulate cortex/precuneus and right middle frontal gyrus that was shared between adult ADHD probands and their first-degree relatives, but not with healthy controls. The observed connectivity alterations were linked to higher ADHD symptoms that was mediated by performance in a sustained attention task. Moreover, this brain-based neurocognitive trait dimensionally explained ADHD symptom variability in the HCP sample.

CONCLUSIONS

Alterations in the default mode connectivity may represent a dimensional endophenotype of ADHD, hence a significant aspect of the neuropathophysiology of this disorder. As such, brain network organisation can potentially be employed as an important neurocognitive trait to enhance statistical power of genetic studies in ADHD and as a surrogate efficacy endpoint in the development of novel pharmaceuticals.

Maternal Ferritin Levels during Pregnancy and ADHD Symptoms in 4-Year-Old Children: Results from the INMA-INfancia y Medio Ambiente (Environment and Childhood) Prospective Birth Cohort Study

Ferritin status during prenatal brain development may influence the risk of attention deficit and hyperactivity disorder (ADHD) symptoms in childhood. We investigated the association of maternal ferritin in pregnancy and ADHD-like symptoms in offspring. A total of 1095 mother-child pairs from three birth cohorts of the INMA Project (Spain) were studied. Maternal plasma ferritin in pregnancy was measured at 11.57 weeks of gestation. Children′s ADHD-like symptoms at ages 4–5 years were assessed using the ADHD Rating Scale-IV. The count model of the zero-inflated Poisson regression model showed a significant inverse association between ferritin (continuous variable) and inattention, β = −0.19 (−0.32, −0.07), for boys. Comparing ferritin level by tertiles, significant differences were observed between the first tertile ([1.98, 20.92]) and the second ([20.92, 38.79]) and third tertiles ([38.79, 216.5]) (mg/L).The number of symptoms was lower for those in the third tertile, β = −0.3 (−0.55, −0.5), and for those in the second one, β = −0.37 (−0.6, −0.14). The model stratification by sex also showed this inverse association for boys only, β = −0.21 (−0.34, −0.08). No associations were found between ferritin level and hyperactivity or total ADHD symptoms. High ferritin levels during pregnancy show a protective association with child inattentive-type ADHD symptoms.

Prediction of sleep side effects following methylphenidate treatment in ADHD youth

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Sleep problems after stimulant use in ADHD were predicted using machine learning.

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Step-wise combination of multi-level features enhanced prediction performance.

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Fronto-striatal connectivity and DAT1, ADRA2A, SLC6A2 SNPs were key features.

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An accuracy of 95.5% was achieved by Logistic Ridge Regression in the training data.

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An accuracy of 86.1% was achieved by J48 in the independent validation analysis.

Objective

Sleep problems is the most common side effect of methylphenidate (MPH) treatment in ADHD youth and carry potential to negatively impact long-term self-regulatory functioning. This study aimed to examine whether applying machine learning approaches to pre-treatment demographic, clinical questionnaire, environmental, neuropsychological, genetic, and neuroimaging features can predict sleep side effects following MPH administration.

Method

The present study included 83 ADHD subjects as a training dataset. The participants were enrolled in an 8-week, open-label trial of MPH. The Barkley Stimulant Side Effects Rating Scale was used to determine the presence/absence of sleep problems at the 2nd week of treatment. Prediction of sleep side effects were performed with step-wise addition of variables measured at baseline: demographics (age, gender, IQ, height/weight) and clinical variables (ADHD Rating Scale-IV (ADHD-RS) and Disruptive Behavior Disorder rating scale) at stage 1, neuropsychological test (continuous performance test (CPT), Stroop color word test) and genetic/environmental variables (dopamine and norepinephrine receptor gene (DAT1, DRD4, ADRA2A, and SLC6A2) polymorphisms, blood lead, and urine cotinine level) at stage 2, and structural connectivities of frontostriatal circuits at stage 3. Three different machine learning algorithms ((Logistic Ridge Regression (LR), support vector machine (SVM), J48) were used for data analysis. Robustness of classifier model was validated in the independent dataset of 36 ADHD subjects.

Results

Classification accuracy of LR was 95.5% (area under receiver operating characteristic curve (AUC) 0.99), followed by SVM (91.0%, AUC 0.85) and J48 (90.0%, AUC 0.87) at stage 3 for predicting sleep problems. The inattention symptoms of ADHD-RS, CPT response time variability, the DAT1, ADRA2A DraI, and SLC6A2 A-3081T polymorphisms, and the structural connectivities between frontal and striatal brain regions were identified as the most differentiating subset of features. Validation analysis achieved accuracy of 86.1% (AUC 0.92) at stage 3 with J48.

Conclusions

Our results provide preliminary support to the combination of multimodal classifier, in particular, neuroimaging features, as an informative method that can assist in predicting MPH side effects in ADHD.

Latrophilins: A Neuro-Centric View of an Evolutionary Conserved Adhesion G Protein-Coupled Receptor Subfamily

The adhesion G protein-coupled receptors latrophilins have been in the limelight for more than 20 years since their discovery as calcium-independent receptors for α-latrotoxin, a spider venom toxin with potent activity directed at neurotransmitter release from a variety of synapse types. Latrophilins are highly expressed in the nervous system. Although a substantial amount of studies has been conducted to describe the role of latrophilins in the toxin-mediated action, the recent identification of endogenous ligands for these receptors helped confirm their function as mediators of adhesion events. Here we hypothesize a role for latrophilins in inter-neuronal contacts and the formation of neuronal networks and we review the most recent information on their role in neurons. We explore molecular, cellular and behavioral aspects related to latrophilin adhesion function in mice, zebrafish, Drosophila melanogaster and Caenorhabditis elegans, in physiological and pathophysiological conditions, including autism spectrum, bipolar, attention deficit and hyperactivity and substance use disorders.

The devil is in the detail: exploring the intrinsic neural mechanisms that link attention-deficit/hyperactivity disorder symptomatology to ongoing cognition

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is a developmental condition that profoundly affects quality of life. Although mounting evidence now suggests uncontrolled mind-wandering as a core aspect of the attentional problems associated with ADHD, the neural mechanisms underpinning this deficit remains unclear. To that extent, competing views argue for (i) excessive generation of task-unrelated mental content, or (ii) deficiency in the control of task-relevant cognition.

METHODS

In a cross-sectional investigation of a large neurotypical cohort (n = 184), we examined alterations in the intrinsic brain functional connectivity architecture of the default mode (DMN) and frontoparietal (FPN) networks during resting state functional magnetic resonance imaging in relation to ADHD symptomatology, which could potentially underlie changes in ongoing thought within variable environmental contexts.

RESULTS

The results illustrated that ADHD symptoms were linked to lower levels of detail in ongoing thought while the participants made more difficult, memory based decisions. Moreover, greater ADHD scores were associated with lower levels of connectivity between the DMN and right sensorimotor cortex, and between the FPN and right ventral visual cortex. Finally, a combination of high levels of ADHD symptomology with reduced FPN connectivity to the visual cortex was associated with reduced levels of detail in thought.

CONCLUSIONS

The results of our study suggest that the frequent mind-wandering observed in ADHD may be an indirect consequence of the deficient control of ongoing cognition in response to increasing environmental demands, and that this may partly arise from dysfunctions in the intrinsic organisation of the FPN at rest.

Attention Deficit Hyperactivity Disorder (ADHD) among Children Aged 6 to 17 Years Old Living in Girja District, Rural Ethiopia

Objective

Attention deficit hyperactivity disorder (ADHD) is one of the most common behavioral disorders in childhood with long-term outcomes. Although ADHD is the most studied behavioral disorders of childhood in developed countries, few studies have been conducted in Ethiopia. The aim of this study was to determine the prevalence of ADHD in rural parts of Ethiopia.

Method

A cross-sectional study was conducted from May to June 2015 among children aged 6 to 17 years living in rural areas. A multistage cluster sampling technique was used to select 1302 participants. The Disruptive Behavior Disorder Rating Scale was used to collect the data. Logistic regression analysis was used to see statistically significant variables.

Result

The prevalence rate of attention deficit hyperactivity disorder (ADHD) among children was 7.3%. Being male (Adjusted Odds Ratio (AOR) = 1.81, 95% CI: (1.13, 2.91)); living with a single parent (AOR = 5.0, 95% CI: (2.35, 10.65)); child birth order/rank (AOR = 2.35, 95% CI: (1.30, 4.25)); and low family socioeconomic status (AOR = 2.43, 95% CI: (1.29, 4.59)) were significantly associated with ADHD.

Conclusion

The ADHD prevalence rate was found to be similar with global reports. Prevention and early management of maternal complications is important to reduce the prevalence of ADHD among children.

ADHD symptoms in a young patient with central diabetes insipidus

Diabetes insipidus is known to be associated with neurodevelopmental disorders. In this case report, we present a child suffering from a central diabetes insipidus (DI) and an attention-deficit/hyperactivity disorder (ADHD). The DI was due to a mutation on the vasopressin gene, impairing its secretion. We discuss the effects of this impairment on the central nervous system and how it might be linked to ADHD symptoms.

BDNF 196 G/A and COMT Val158Met Polymorphisms and Susceptibility to ADHD: A Meta-Analysis

OBJECTIVE

The aim of this study was to determine whether the brain-derived neurotrophic factor ( BDNF) 196 G/A or catechol- O-methyltransferase ( COMT) Val158Met polymorphisms is associated with susceptibility to ADHD.

METHOD

We conducted a meta-analysis of the associations between the BDNF 196 G/A and COMT Val158Met polymorphisms and ADHD.

RESULTS

Sixteen studies consisting of 3,594 patients with ADHD and 4,040 controls were included in this meta-analysis. Our results showed no association between ADHD and the BDNF 196A allele in all participants (odds ratio [OR] = 0.958, 95% confidence interval [CI] = [0.800, 1.146], p = .638), European or Asian population. Meta-analysis indicated no association between ADHD and the COMT G allele in all study participants (OR = 1.078, 95% CI = [0.962, 1.207], p = .196), European or Asian population.

CONCLUSION

This meta-analysis showed a lack of association between the BDNF 196 G/A and COMT Val158Met polymorphisms and ADHD.

Meta-Analysis of Case-Control and Family-Based Associations Between the 5-HTTLPR L/S Polymorphism and Susceptibility to ADHD

OBJECTIVE

The aim of this study was to determine whether the serotonin transporter-linked polymorphic region (5-HTTLPR) L (long)/S (short) polymorphism is associated with susceptibility to ADHD.

METHOD

We conducted a meta-analysis of case-control associations and the transmission disequilibrium test (TDT) between the 5-HTTLPR L/S polymorphism and ADHD.

RESULTS

A total of 19 comparison studies were included in this meta-analysis. Our meta-analysis of the case-control studies showed no association between ADHD and the 5-HTTLPR S allele, for all study participants (odds ratio [OR] = 1.075, 95% confidence interval [CI] = [0.990, 1.167], p = .085), or for the European or Asian population. The TDT indicated no association between ADHD and the 5-HTTLPR S allele, for all study participants (OR = 1.078, 95% CI = [0.962, 1.207], p = .196).

CONCLUSION

This meta-analysis of case-control studies and TDT showed a lack of association between the 5-HTTLPR L/S polymorphism and ADHD.

Methylphenidate effects in the young brain: friend or foe?

Attention deficit hyperactivity disorder (ADHD) is one of the most prevalent neuropsychiatry disorders in children and adolescents, and methylphenidate (MPH) is a first-line stimulant drug available worldwide for its treatment. Despite the proven therapeutic efficacy, concerns have been raised regarding the possible consequences of chronic MPH exposure during childhood and adolescence. Disturbances in the neurodevelopment at these crucial stages are major concerns given the unknown future life consequences. This review is focused on the long-term adverse effects of MPH to the brain biochemistry. Reports conducted with young and/or adolescent animals and studies with humans are reviewed in the context of long-term consequences after early life-exposure. MPH pharmacokinetics is also reviewed as there are differences among laboratory animals and humans that may be relevant to extrapolate the findings. Studies reveal that exposure to MPH in laboratory animals during young and/or adolescent ages can impact the brain, but the outcomes are dependent on MPH dose, treatment period, and animal's age. Importantly, the female sex is largely overlooked in both animal and human studies. Unfortunately, human reports that evaluate adults following adolescent or child exposure to MPH are very scarce. In general, human data indicates that MPH is generally safe, although it can promote several brain changes in early ages. Even so, there is a lack of long course patient evaluation to clearly establish whether MPH-induced changes are friendly or foe to the brain and more human studies are needed to assess the adult brain changes that arise from early MPH treatment.

The Investigation of Symptoms and Diagnoses of Adult-Attention Deficit/ Hyperactivity Disorder in Women with Iron Deficiency Anemia

INTRODUCTION

The aim of this study was to investigate symptoms and diagnoses of Adult-Attention Deficit/Hyperactivity Disorder (ADHD) in women with iron deficiency anemia, to evaluate relationship between ADHD with clinical features and to compare with the women without iron deficiency anemia.

METHODS

Eighty-three newly diagnosed iron deficiency anemia patients and 70 healthy controls were included in this study. All participants were assessed using a sociodemographic form, Structured Clinical Interview I (SCID-I), Wender Utah Rating Scale (WURS); Moreover, participants having WURS scores 36 and above were also assessed using the Adult ADD/ADHD Evaluation Scale and interviewed according to DSM-5 criteria.

RESULTS

In the study, 22.9% of patients with iron deficiency anemia and 12.9% of healthy controls were found to have WURS scores 36 and above. Fifteen patients (18.1%) in iron deficiency anemia group and two patients (2.9%) in control group had adult ADHD, when they were evaluated with Adult ADD/ADHD Evaluation Scale and interviewed according to DSM-5 criteria (p=0.007). The patients with iron deficiency anemia had significantly higher WURS scores compared to controls (p=0.002). The levels of iron and ferritin had negative correlation (r=-0.166, p<0.05; r=-0.255, p<0.01, respectively) and the levels of serum iron binding capacity had positive correlation (r=0.255, p<0.01) with the scores of WURS.

CONCLUSION

The prevalence of adult ADHD is higher than those reported for general population in patients with iron deficiency anemia. Early diagnose and treatment of adult ADHD may positively contribute to the patients with iron deficiency anemia.

Headache and ADHD in Pediatric Age: Possible Physiopathological Links

Primary headache and attention-deficit/hyperactivity disorder (ADHD) are common disorders in children and adolescences, frequently associated to severe cognitive, emotional, and behavioral impairments. They both are a disabling condition with consequences on family and child's quality of life. Literature data on their association are contrasting. Dopaminergic system dysfunction, brain iron deficiency, and sleep disturbance should be considered to better understand headache and ADHD overlap. In this review, we analyze the complex association between these two diseases and the potential impact on child neurodevelopment.

A Developmental Psychopathology Perspective on ADHD and Comorbid Conditions: The Role of Emotion Regulation

Research investigating attention-deficit/hyperactivity disorder (ADHD) and co-occurring disorders such as oppositional defiant disorder, conduct disorder, anxiety, and depression has surged in popularity; however, the developmental relations between ADHD and these comorbid conditions remain poorly understood. The current paper uses a developmental psychopathology perspective to examine conditions commonly comorbid with ADHD during late childhood through adolescence. First, we present evidence for ADHD and comorbid disorders. Next, we discuss emotion regulation and its associations with ADHD. The role of parenting behaviors in the development and maintenance of emotion regulation difficulties and comorbid disorders among children with ADHD is explored. An illustrative example of emotion regulation and parenting over the course of development is provided to demonstrate bidirectional relations among these constructs. We then present an integrated conceptual model of emotion regulation as a shared risk process that may lead to different comorbid conditions among children with ADHD. Implications and directions for future research are presented.

Neuropsychological and dimensional behavioral trait profiles in Costa Rican ADHD sib pairs: Potential intermediate phenotypes for genetic studies

Attention deficit hyperactivity disorder (ADHD) is associated with substantial functional impairment in children and in adults. Many individuals with ADHD have clear neurocognitive deficits, including problems with visual attention, processing speed, and set shifting. ADHD is etiologically complex, and although genetic factors play a role in its development, much of the genetic contribution to ADHD remains unidentified. We conducted clinical and neuropsychological assessments of 294 individuals (269 with ADHD) from 163 families (48 multigenerational families created using genealogical reconstruction, 78 affected sib pair families, and 37 trios) from the Central Valley of Costa Rica (CVCR). We used principal components analysis (PCA) to group neurocognitive and behavioral variables using the subscales of the Child Behavior Checklist (CBCL) and 15 neuropsychological measures, and created quantitative traits for heritability analyses. We identified seven cognitive and two behavioral domains. Individuals with ADHD were significantly more impaired than their unaffected siblings on most behavioral and cognitive domains. The verbal IQ domain had the highest heritability (92%), followed by auditory attention (87%), visual processing speed and problem solving (85%), and externalizing symptoms (81%). The quantitative traits identified here have high heritabilities, similar to the reported heritability of ADHD (70-90%), and may represent appropriate alternative phenotypes for genetic studies. The use of multigenerational families from a genetically isolated population may facilitate the identification of ADHD risk genes in the face of phenotypic and genetic heterogeneity.

Predicting Methylphenidate Response in ADHD Using Machine Learning Approaches

BACKGROUND

There are no objective, biological markers that can robustly predict methylphenidate response in attention deficit hyperactivity disorder. This study aimed to examine whether applying machine learning approaches to pretreatment demographic, clinical questionnaire, environmental, neuropsychological, neuroimaging, and genetic information can predict therapeutic response following methylphenidate administration.

METHODS

The present study included 83 attention deficit hyperactivity disorder youth. At baseline, parents completed the ADHD Rating Scale-IV and Disruptive Behavior Disorder rating scale, and participants undertook the continuous performance test, Stroop color word test, and resting-state functional MRI scans. The dopamine transporter gene, dopamine D4 receptor gene, alpha-2A adrenergic receptor gene (ADRA2A) and norepinephrine transporter gene polymorphisms, and blood lead and urine cotinine levels were also measured. The participants were enrolled in an 8-week, open-label trial of methylphenidate. Four different machine learning algorithms were used for data analysis.

RESULTS

Support vector machine classification accuracy was 84.6% (area under receiver operating characteristic curve 0.84) for predicting methylphenidate response. The age, weight, ADRA2A MspI and DraI polymorphisms, lead level, Stroop color word test performance, and oppositional symptoms of Disruptive Behavior Disorder rating scale were identified as the most differentiating subset of features.

CONCLUSIONS

Our results provide preliminary support to the translational development of support vector machine as an informative method that can assist in predicting treatment response in attention deficit hyperactivity disorder, though further work is required to provide enhanced levels of classification performance.

Association of norepinephrine transporter (NET, SLC6A2) genotype with ADHD-related phenotypes: findings of a longitudinal study from birth to adolescence

Variation in the gene encoding for the norepinephrine transporter (NET, SLC6A2) has repeatedly been linked with ADHD, although there is some inconsistency regarding the association with specific genes. The variants for which most consistent association has been found are the NET variants rs3785157 and rs28386840. Here, we tested for their association with ADHD diagnosis and ADHD-related phenotypes during development in a longitudinal German community sample. Children were followed from age 4 to age 15, using diagnostic interviews to assess ADHD. Between the ages of 8 and 15 years, the Child Behavior Checklist (CBCL) was administered to the primary caregivers. The continuous performance task (CPT) was performed at age 15. Controlling for possible confounders, we found that homozygous carriers of the major A allele of the functional promoter variant rs28386840 displayed a higher rate of ADHD lifetime diagnosis. Moreover, homozygous carriers of the minor T allele of rs3785157 were more likely to develop ADHD and showed higher scores on the CBCL externalizing behavior scales. Additionally, we found that individuals heterozygous for rs3785157 made fewer omission errors in the CPT than homozygotes. This is the first longitudinal study to report associations between specific NET variants and ADHD-related phenotypes during the course of development.

Child attention deficit hyperactive disorder co morbidities on family stress: effect of medication

We examined the degree of parental and child mental health in a community sample of children diagnosed with Attention Deficit Hyperactive Disorder and the effect on family stress prior to and during treatment using a community retrospective questionnaire study. In total 358 questionnaires were returned for analysis where 92 % of children had at least one co-morbid condition and mental health conditions in parents was common. Overall, the Family Strain Index was significantly reduced after commencement of medication (p < 0.0001), but remained higher in families where the children had either externalizing disorders or autism spectrum disorder.

No association of the norepinephrine transporter gene (SLC6A2) and cognitive and behavioural phenotypes of patients with autism spectrum disorder

We examined the association between the norepinephrine transporter (SLC6A2) gene and autism spectrum disorder (ASD) in a Korean population. In addition, we investigated which phenotypes of ASD are best attributed to the genotype of SLC6A2. A total of 184 subjects with ASD, their 156 unaffected siblings and both biological parents were recruited through university hospitals. We used the Autism Diagnostic Interview-Revised, the Aberrant Behaviour Checklist (ABC), the Child Behaviour Checklist (CBCL), the Stroop Colour-Word Interference Test and the Wisconsin Card Sorting Test (WCST) as quantitative measures of the ASD phenotypes. The associations between the quantitative measures and specific single-nucleotide polymorphisms (SNPs) were tested with linear regression analyses. We did not find any evidence of the over-transmission of either allele of the 10SLC6A2 SNPs in the DFAM test. At an empirical p value <0.05, findings that were consistent between the linear regression analyses and the QFAM tests were the positive associations between the A allele of rs36020 and attention problems on the CBCL and stereotypical behaviours on the ABC and between the C allele of rs1814270 and the number of trials required to complete the first WCST category. However, these associations did not remain after correction for multiple testing. The study results of this study do not support the association between the SLC6A2 and the diagnosis or phenotype of ASD. However, the study must be replicated in larger populations and with using more genetic markers.

The comorbidity of ADHD and autism spectrum disorder

ADHD and autism spectrum disorder are common psychiatric comorbidities to each another. In addition, there is behavioral, biological and neuropsychological overlap between the two disorders. There are also several important differences between autism spectrum disorder and ADHD. Treatment strategies for the comorbid condition will also be reviewed. Future areas of research and clinical need will be discussed.

Catechol-o-methyltransferase gene and executive function in children with ADHD

OBJECTIVE

To examine the association between functional haplotypes in the catechol-o-methyltransferase (COMT) gene and ADHD diagnosis, and executive function (EF) in children with ADHD.

METHOD

COMT single nucleotide polymorphism (SNPs; rs6269, rs4633, rs4818, and rs4680) were genotyped in 445 ADHD children. EF was assessed using Wisconsin Card Sorting Test (WCST), Tower of London, and self-ordered pointing task. COMT haplotypes were tested for association using family-based association testing (fBAT) and quantitative trait analyses.

RESULTS

fBAT analysis showed no association between COMT alleles/haplotypes and ADHD diagnosis and EF parameters. Using ANCOVA in the Caucasian only sample, significant associations between COMT haplotypes, and WCST indices were observed. However, after correction for multipletesting, the only significant effect observed was between rs6269 and the number of categories completed (a measure of concept formation ability) on the WCST, F(1,285) = 8.92, p = .003.

CONCLUSION

These results tentatively implicate COMT gene in modulating EF in children with ADHD.

Headache and attention deficit and hyperactivity disorder in children: common condition with complex relation and disabling consequences

The aim of this review was to analyze literature data on the complex association between headache and attention deficit and hyperactivity disorder (ADHD) in children, in order to explore its possible consequences on child neurological development. Headache and ADHD are two common conditions in the pediatric population. They both are disabling diseases that impact the child's quality of life and are associated with severe cognitive, emotional, and behavioral impairments. To assess and analyze literature data about the association of ADHD and headache in children and possible physiopathogenesis relationships, we searched for the following terms: headache, migraine, tension-type headache, ADHD, and children (MESH or text words). We found different studies that assess the clinical, epidemiological, and physiopathogenetic overlap between these two diseases, with contrasting results and unresolved questions. Structural and functional abnormalities in brain networks have been found to be central in both headache and ADHD pathophysiology. It will be crucial to gain a better understanding of how subcortical-cortical and corticocortical network development is altered during the onset of the disorders.

Association of VAMP-2 and Syntaxin 1A Genes with Adult Attention Deficit Hyperactivity Disorder

OBJECTIVE

The etiology of attention deficit hyperactivity disorder (ADHD) has not been entirely clarified yet. Structural and metabolic differences at the prefrontal striatal cerebellary system and the interaction of gene and environment are the main factors that thought to play roles in the etiology. Genetic investigations are performed especially about the dopamine pathways and receptors. In this study; it was aimed to investigate the association of the synaptobrevin-2 (VAMP-2) gene Ins/Del polymorphism and syntaxin 1A gene intron 7 polymorphism, which take place in encoding presynaptic protein, with adult ADHD.

METHODS

One hundred thirty-nine patients, having ADHD aging between 18 and 60 years and 106 healthy people as controls were included into the study. DNA samples were extracted from whole blood and genetic analysis were performed.

RESULTS

A significant difference was determined between ADHD and VAMP-2 Ins/Del polymorphism and syntaxin 1A intron 7 polymorphism according to the control group. These polymorphisms were found not to be associated with subtypes of ADHD.

CONCLUSION

It is supposed that synaptic protein genes together with dopaminergic genes might have roles in the etiology of ADHD.

Association of genetic risk severity with ADHD clinical characteristics

This study sought to examine the association between the cumulative risk severity conferred by the total number of attention-deficit/hyperactivity disorder (ADHD) risk alleles of the DAT1 3'UTR variable number tandem repeat (VNTR), DRD4 Exon 3 VNTR, and 5-HTTLPR with ADHD characteristics, clinical correlates, and functional outcomes in a pediatric sample. Participants were derived from case-control family studies of boys and girls diagnosed with ADHD, a genetic linkage study of families with children with ADHD, and a family genetic study of pediatric bipolar disorder. Caucasian children 18 and younger with and without ADHD and with available genetic data were included in this analysis (N = 591). The association of genetic risk severity with sociodemographic, clinical characteristics, neuropsychological, emotional, and behavioral correlates was examined in the entire sample, in the sample with ADHD, and in the sample without ADHD, respectively. Greater genetic risk severity was significantly associated with the presence of disruptive behavior disorders in the entire sample and oppositional defiant disorder in participants with ADHD. Greater genetic risk severity was also associated with the absence of anxiety disorders, specifically with the absence of agoraphobia in the context of ADHD. Additionally, one ADHD symptom was significantly associated with greater genetic risk severity. Genetic risk severity is significantly associated with ADHD clinical characteristics and co-morbid disorders, and the nature of these associations may vary on the type (externalizing vs. internalizing) of the disorder.

Risikofaktoren und frühe Vorläufersymptome der Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung (ADHS)

Einer ADHS liegen in der Regel multiple miteinander interagierende Faktoren zugrunde. Zu den Risikofaktoren zählen neben genetischen Faktoren auch verschiedene Umwelteinflüsse wie sozioökonomische Risiken oder mütterlicher Substanzkonsum. Diese Umwelteinflüsse können jedoch teilweise auch Ausdruck einer entsprechenden genetischen Prädisposition der Eltern für eine ADHS darstellen, sodass eine klare Trennung zwischen genetischen und umweltbedingten Einflüssen auf die Entstehung der ADHS nur begrenzt möglich und sinnvoll ist. Da der Störung ein komplexes Zusammenspiel multipler voneinander unabhängiger Risikofaktoren zugrunde liegt, wird ADHS inzwischen eher im Sinne einer Dimension denn im Sinne einer Kategorie verstanden. Im Rahmen dieser Arbeit soll ein Überblick über die neuesten Erkenntnisse bezüglich Risikofaktoren und Vorläufersymptomen von ADHS gegeben werden.

Catecholaminergic gene variants: contribution in ADHD and associated comorbid attributes in the eastern Indian probands

Contribution of genes in attention deficit hyperactivity disorder (ADHD) has been explored in various populations, and several genes were speculated to contribute small but additive effects. We have assessed variants in four genes, DDC (rs3837091 and rs3735273), DRD2 (rs1800496, rs1801028, and rs1799732), DRD4 (rs4646984 and rs4646983), and COMT (rs165599 and rs740603) in Indian ADHD subjects with comorbid attributes. Cases were recruited following the Diagnostic and Statistical Manual for Mental Disorders-IV-TR after obtaining informed written consent. DNA isolated from peripheral blood leukocytes of ADHD probands (N = 170), their parents (N = 310), and ethnically matched controls (n = 180) was used for genotyping followed by population- and family-based analyses by the UNPHASED program. DRD4 sites showed significant difference in allelic frequencies by case-control analysis, while DDC and COMT exhibited bias in familial transmission (P < 0.05). rs3837091 “AGAG,” rs3735273 “A,” rs1799732 “C,” rs740603 “G,” rs165599 “G” and single repeat alleles of rs4646984/rs4646983 showed positive correlation with co-morbid characteristics (P < 0.05). Multi dimensionality reduction analysis of case-control data revealed significant interactive effects of all four genes (P < 0.001), while family-based data showed interaction between DDC and DRD2 (P = 0.04). This first study on these gene variants in Indo-Caucasoid ADHD probands and associated co-morbid conditions indicates altered dopaminergic neurotransmission in ADHD.

Iron and ADHD: time to move beyond serum ferritin levels

OBJECTIVE

(a) To compare serum ferritin levels in a sample of stimulant-naïve children with ADHD and matched controls and (b) to assess the association of serum ferritin to ADHD symptoms severity, ADHD subtypes, and IQ.

METHOD

The ADHD and the control groups included 101 and 93 children, respectively. Serum ferritin levels were determined with the enzyme-linked immunosorbent assay method.

RESULTS

Serum ferritin did not significantly differ between children with ADHD and controls, as well as among ADHD subtypes. Correlations between serum ferritin levels and measures related to IQ or ADHD severity were not significant.

CONCLUSION

This is the largest controlled study that assessed ferritin levels in stimulant-naïve ADHD children. The findings of this study do not support a significant relationship between serum ferritin levels and ADHD. However, the authors' results based on peripheral measures of iron do not rule out a possible implication of brain iron deficiency in ADHD, grounded on neurobiological hypotheses and preliminary empirical evidence.

The Brazilian contribution to Attention-Deficit/Hyperactivity Disorder molecular genetics in children and adolescents

Attention-Deficit/Hyperactivity Disorder (ADHD) is a common psychiatric condition of children worldwide. This disorder is defined by a combination of symptoms of inattention and hyperactivity/impulsivity. Diagnosis is based on a sufficient number of symptoms causing impairment in these two domains determining several problems in personal and academic life. Although genetic and environmental factors are important in ADHD etiology, how these factors influence the brain and consequently behavior is still under debate. It seems to be consensus that a frontosubcortical dysfunction is responsible, at least in part, for the ADHD phenotype spectrum. The main results from association and pharmacogenetic studies performed in Brazil are discussed. The investigations performed so far on ADHD genetics in Brazil and elsewhere are far from conclusive. New plausible biological hypotheses linked to neurotransmission and neurodevelopment, as well as new analytic approaches are needed to fully disclose the genetic component of the disorder.

Molecular genetics research in ADHD: ethical considerations concerning patients' benefit and resource allocation

Immense resource allocations have led to great data output in genetic research. Concerning ADHD resources spent on genetic research are less than those spent on clinical research. But there are successful efforts made to increase support for molecular genetics research in ADHD. Concerning genetics no evidence based conclusive results have significant impact on prevention, diagnosis or treatment yet. With regard to ethical aspects like the patients' benefit and limited resources the question arises if it is indicated to think about a new balance of resource allocation between molecular genetics and non-genetics research in ADHD. An ethical reflection was performed focusing on recent genetic studies and reviews based on a selective literature search. There are plausible reasons why genetic research results in ADHD are somehow disappointing for clinical practice so far. Researchers try to overcome these gaps systematically, without knowing what the potential future benefits for the patients might be. Non-genetic diagnostic/therapeutic research may lead to clinically relevant findings within a shorter period of time. On the other hand, non-genetic research in ADHD may be nurtured by genetic approaches. But, with the latter there exist significant risks of harm like stigmatization and concerns regarding data protection. Isolated speeding up resources of genetic research in ADHD seems questionable from an ethical point of view. There is a need to find a new balance of resource allocation between genetic and non-genetic research in ADHD, probably by integrating genetics more systematically into clinical research. A transdisciplinary debate is recommended.

Association study between the dopamine-related candidate gene polymorphisms and ADHD among Saudi Arabia population via PCR technique

Attention deficit hyperactivity disorder (ADHD) is one of the most common childhood behavioral disorders characterized by inattention, hyperactivity and impulsivity. In Saudi Arabia the prevalence of combined ADHD is 16.4 %. ADHD etiology is not clear and not completely understood. There are several evidences for involvement of dopaminergic, serotonergic and noradrenergic neurotransmitter systems in the pathogenesis of ADHD. Monoamine Oxidase A (MAOA) is involved in the degradation of all three of these neurotransmitters. Dopamine Transporter 1 (DAT1) plays an important role in controlling blood levels of dopamine. The aim of the present study is to investigate the association between ADHD and polymorphisms of MAOA 30 bp-promoter VNTR and DAT1 40 bp 3' UTRVNTR in Saudi population. PCR technique was employed to detect polymorphisms of MAOA and DAT1 genes in a sample of 120 ADHD subjects and 160 controls. Alleles and genotypes frequencies for both of MAOA and DAT1 polymorphisms were compared among ADHD subjects against controls. Association between ADHD and alleles as well as genotypes for each studied polymorphisms was tested by odds ratio (OR) test and the magnitude of this association was estimated by 95 % confidence interval (95 % CI). A significant association was found between two MAOA genotypes 3/4 and 3/2 with ADHD (P < 0.01, OR = 3, 4.9) as a risk effect. No significant association was found with MAOA alleles. Among DAT1 polymorphisms two alleles (7 and 11 repeats) (P < 0.01, OR = 2.5 and 3.3) as well as two genotypes (11/11 and 11/7) (P < 0.01, OR = 4, 3) showed significant association with ADHD as a risk effect. On the contrary, 9 and 10 repeats revealed significant association as a protective effect as well as 10/10 and 10/9 genotypes. These findings support the hypothesis that some of the MAOA and DAT1 polymorphisms have a causative role in the development of ADHD in the Saudi population. Another polymorphism did not give rise to support this hypothesis. This is the first report investigated the association between MAOA and DAT1 polymorphism at molecular level in Saudi Arabia population as well as Arab world. Therefore further studies are needed to generalize obtained results at Saudi Arabia.

Ferritin and hyperactivity ratings in attention deficit hyperactivity disorder

BACKGROUND

Iron is a co-factor of tyrosine hydroxylase which is a critical enzyme in dopamine synthesis. Dopamine has been implicated in the pathophysiology of attention deficit hyperactivity disorder (ADHD). Our objective was to investigate the association of ferritin level with parent and teacher ratings and cognitive measures after controlling for age, sex, ADHD subtype, comorbid conditions, hemoglobin, mean corpuscular volume and reticulocyte distribution width in a large sample.

METHODS

The study included 713 children and adolescents with ADHD (613 boys; age 7-15 years). Conners' Parent Rating Scale (CPRS) and Conners' Teacher Rating Scale (CTRS) were obtained. In a subgroup of patients we conducted Digit Span, Digit Symbol, Trail-making Tests as measures of attention and executive functioning.

RESULTS

Multiple regression analysis indicated that CPRS Hyperactivity score was significantly associated with ferritin level (B =-0.12; t =-3.1; P < 0.01). Other CPRS and CTRS scores as well as cognitive measures were not associated with ferritin level.

CONCLUSIONS

Although it is not possible to make an inference on causality in cross-sectional studies, the results of this largest-scale cross-sectional field study to date suggest that lower ferritin level might be associated with parent-reported hyperactivity after controlling for important confounding factors.

Characteristics and comorbidity of ADHD sib pairs in the Central Valley of Costa Rica

BACKGROUND

While genetic epidemiological studies demonstrate a substantial degree of genetic predisposition for attention-deficit/hyperactivity disorder (ADHD), they also suggest that the genetics are complex and may differ between populations or ethnic groups.

OBJECTIVE

This study describes the phenomenology of siblings with ADHD from the genetically isolated population of the Central Valley of Costa Rica.

METHODS

Rates of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV)-defined ADHD subtypes and comorbid conditions were calculated in a sample of 157 ADHD-affected children (probands and siblings) recruited for genetic studies using standardized approaches. Sib-sib comparisons and logistic regressions were conducted to identify significant patterns of concordance.

RESULTS

Combined-type ADHD (69.5%) was the most common subtype among probands, followed by the inattentive (27.4%), and hyperactive-impulsive (3.2%) subtypes. Anxiety disorders were prevalent (55.9%), as were disruptive behavior disorders (30.9%) and Tourette disorder (17.0%). Probands and siblings showed high sib-sib concordance for anxiety disorders.

CONCLUSIONS

ADHD in Costa Rica is similar in clinical and demographic characteristics to ADHD seen in other parts of the world, although the rates of co-occurring psychiatric disorders differ somewhat from those previously reported in Latin American samples. Comorbid anxiety is prevalent, with high rates of sib-sib concordance, and may represent a distinct, homogeneous subgroup suitable for genetic studies.

Das ADHS-Camp

Die Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung (ADHS) ist eine der am häufigsten gestellten Diagnosen im Bereich der Kinder- und Jugendlichenpsychotherapie. Verschiedene Studien belegen die Wirksamkeit multimodaler Maßnahmen und verweisen dabei auf die Bedeutung der Verhaltenstherapie, deren Wirksamkeit bereits in verschiedenen Studien belegt wurde. Da sich viele Therapieangebote über einen langen Zeitraum erstrecken, wurde das ADHS-Camp als zeitökonomisches, intensivtherapeutisches Vorgehen entwickelt und dessen Wirksamkeit im Rahmen dieser Studie auf Langzeiteffekte (6 und 12 Monate nach Abschluss der Therapie) überprüft. Dies geschah unter Einbezug funktionsorientierter (neuropsychologischer) und verhaltensorientierter Testverfahren, wobei letztere von Eltern und Lehrern beurteilt wurden. Über die Berechnung von MAN(C)OVAS mit Messwiederholung zeigte sich, dass das ADHS-Camp zu einer signifikanten Verbesserung sowohl auf funktioneller als auch verhaltensorientierter Ebene führt. Auf der Verhaltensebene sehen Eltern einen stärkeren Einfluss als die Lehrer. Um zu gewährleisten, dass die Effekte nicht durch normale Reifungsprozesse beeinflusst sind, wurde das Alter als Kovariate aufgenommen. Es zeigt sich, dass das ADHS-Camp als eine wirkungsvolle Maßnahme bewertet werden kann. Erzielte Verbesserungen der Problemlage sind sowohl auf der funktionellen als auch der Verhaltensebene zeitstabil. Dies unterstreicht die Relevanz intensivtherapeutischer Maßnahmen zur Behandlung von ADHS bei Kindern.

Brain iron levels in attention-deficit/hyperactivity disorder: a pilot MRI study

OBJECTIVE

Brain iron deficiency has been supposed to be involved in the pathophysiology of ADHD. Available studies assessing iron in ADHD are based on serum ferritin, a peripheral marker of iron status. To what extent serum ferritin correlates with brain iron (BI) is unclear. The main aim of this study was to compare BI, estimated with magnetic resonance imaging (MRI) in the putamen, pallidum, caudate, and thalamus, between children with and without ADHD. The secondary aim was to assess the correlation between serum ferritin and BI levels.

METHODS

Thirty-six children (18 with and 18 without ADHD, the latter including nine healthy controls and nine psychiatric controls) completed MRI and blood sampling. Brain iron levels were estimated by imaging T2*.

RESULTS

Children with ADHD showed significantly lower estimated BI in right and left thalamus compared to healthy controls. Estimated BI did not differ significantly between children with ADHD and psychiatric controls. Children with ADHD had significantly lower levels of serum ferritin than healthy as well as psychiatric controls. Serum ferritin and T2* values did not correlate significantly in most regions.

CONCLUSIONS

Low iron in the thalamus may contribute to ADHD pathophysiology.

Associations between mothers' and children's secure base scripts in ADHD and community cohorts

This study explored the relation between mothers' and their children's secure base scripts in two samples of school-aged children: a community sample (N = 29; mean age 8.9) and a sample of children diagnosed with ADHD (N = 50; mean age 8.9). Using the Attachment Script Representation Task, mothers and children were asked to construct narratives using word prompt outlines. In addition, mothers and children completed questionnaires focusing on symptoms. The results revealed that while the link between mothers' and children's scriptedness was significant in the community, no significant association was found in the ADHD sample. In the ADHD group, maternal reports of children's symptoms were negatively linked to children's secure-base scriptedness. Implications of these findings for theory and intervention are discussed.

Dose response effects of lisdexamfetamine dimesylate treatment in adults with ADHD: an exploratory study

OBJECTIVE

To explore dose-response effects of lisdexamfetamine dimesylate (LDX) treatment for ADHD.

METHOD

This was a 4-week, randomized, double-blinded, placebo-controlled, parallel-group, forced-dose titration study in adult participants, aged 18 to 55 years, meeting Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.) criteria for ADHD.

RESULTS

Nearly all participants assigned to an LDX dose achieved their assigned dose with the exception of about 4% of participants assigned to the 50 mg or 14% assigned to the 70 mg doses. Higher doses of LDX led to greater improvements in ADHD-rating scale scores, independent of prior pharmacotherapy. This was evident for both inattentive and hyperactive-impulsive symptoms. The authors found some evidence for an interaction between LDX dose and baseline severity of ADHD symptoms.

CONCLUSION

For LDX doses between 30 and 70 mg/d, the dose-response efficacy effect for LDX is not affected by prior pharmacotherapy, but patients with a greater severity of illness may benefit more from higher doses, especially for hyperactive-impulsive symptoms. The results do not provide information about doses above 70 mg/d, which is the maximum approved dose of LDX and the highest dose studied in ADHD clinical trials.

Epigenetics: genetics versus life experiences

Epigenetics is the field of research that examines alterations in gene expression caused by mechanisms other than changes in DNA sequence. ADHD is highly heritable; however, epigenetics are considered relevant in potentially explaining the variance not accounted for by genetic influence. In this chapter, some of the well-known processes of epigenetics, such as chromosome organization, DNA methylation, and effects of transcriptional factors are reviewed along with studies examining the role of these processes in the pathophysiology of ADHD. Potential epigenetic factors conferring risk for ADHD at various developmental stages, such as alcohol, tobacco, toxins, medications, and psychosocial stressor are discussed. Animal studies investigating ADHD medications and changes in CNS Gene/Protein Expression are also explored since they provide insight into the neuronal pathways involved in ADHD pathophysiology. The current limited data suggest that identification of the epigenetic processes involved in ADHD is extremely important and may lead to potential interventions that may be applied to modify the expression of deleterious, as well as protective, genes.

Genome-wide copy number variation study associates metabotropic glutamate receptor gene networks with attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is a common, heritable neuropsychiatric disorder of unknown etiology. We performed a whole-genome copy number variation (CNV) study on 1,013 cases with ADHD and 4,105 healthy children of European ancestry using 550,000 SNPs. We evaluated statistically significant findings in multiple independent cohorts, with a total of 2,493 cases with ADHD and 9,222 controls of European ancestry, using matched platforms. CNVs affecting metabotropic glutamate receptor genes were enriched across all cohorts (P = 2.1 × 10(-9)). We saw GRM5 (encoding glutamate receptor, metabotropic 5) deletions in ten cases and one control (P = 1.36 × 10(-6)). We saw GRM7 deletions in six cases, and we saw GRM8 deletions in eight cases and no controls. GRM1 was duplicated in eight cases. We experimentally validated the observed variants using quantitative RT-PCR. A gene network analysis showed that genes interacting with the genes in the GRM family are enriched for CNVs in ∼10% of the cases (P = 4.38 × 10(-10)) after correction for occurrence in the controls. We identified rare recurrent CNVs affecting glutamatergic neurotransmission genes that were overrepresented in multiple ADHD cohorts.

Prevalence of attention deficit hyperactivity disorder and associated features among children in France

BACKGROUND

Earlier studies point to the prevalence of attention deficit hyperactivity disorder (ADHD) to be similar around the world. There is, however, a wide variety in estimates. The prevalence of ADHD in youth has never been examined in France.

METHOD

Starting with 18 million telephone numbers, 7,912 numbers are randomly selected. Among the 4,186 eligible families, 1,012 (24.2%) are successfully recruited. A telephone interview is administered to all families about a child in the 6 to 12 age range. It covered family living situation, school performance, symptoms of ADHD, conduct disorder (CD), and oppositional-defiant disorder (ODD), and other features of ADHD.

RESULTS

The prevalence of ADHD in France is between 3.5% and 5.6%. The population prevalence of treatment for ADHD is 3.5%. ADHD youth are more likely to be men than women, and, compared to non-ADHD children, ADHD children are more likely to have CD and ODD. Having ADHD is associated with a family history of the disorder. The ADHD youth are more likely to have had learning difficulties, to have repeated a grade, and to be functioning academically below grade level.

CONCLUSIONS

The epidemiology of ADHD in French children is similar to the epidemiology of ADHD in other countries. The disorder occurs in between 3.5% to 5.6% of youth and is more common among boys than among girls. The authors replicate the well-known association of ADHD with CD, ODD, and indices of school failure. The impact of ADHD symptoms on school performance highlights the importance of screening for such symptoms in schools.

Are stimulants effective in the treatment of executive function deficits? Results from a randomized double blind study of OROS-methylphenidate in adults with ADHD

The objective of this study was to evaluate the association between executive function deficits (EFDs) and response to methylphenidate treatment in ADHD in adults. We conducted a 6-week, parallel design, randomized, placebo controlled study in adults with DSM-IV ADHD. Our psychometric index of executive function used standardized neuropsychological testing. We assessed behaviors reflective of EFDs using the Behavior Rating Inventory of Executive Function--Adult Version (BRIEF-A). Subjects with available measures of executive functioning (OROS-MPH N=40; Placebo N=47) were included for analysis. There was no difference in the percent of subjects completing the 6-week acute efficacy Phase I of the trial (100% (N=40) vs. 98% (N=46), p=0.4). The mean daily dose at Phase I endpoint was 84.6±31.6 mg (1.04±0.29 mg/kg) OROS-MPH and 100.5±21.9 mg (1.20±0.11 mg/kg) placebo (p=0.0007). Based on the neuropsychological testing at the baseline assessment, 40% of the ADHD subjects (N=35/87) were considered to have EFDs but 93% (N=81) of subjects had ≥ 2 BRIEF-A clinical scale T-scores > 65. Regardless of the definition used, however, EFDs did not impact the clinical response to OROS-MPH. This randomized clinical trial showed that executive function deficits do not moderate the response to methylphenidate and measures of executive function deficits are not associated with response to OROS-MPH.