The heterogeneity of causes and courses of attention-deficit/hyperactivity disorder

Looking beyond psychosocial adversity and sex: Clinical factors associated with ADHD and other psychiatric disorders in a non-Caucasian sample of high-risk siblings

This study examined the association of clinical factors, independent of sex and high psychosocial adversity (HPAd), with the presence of ADHD or other mental disorders, specifically within a middle-income country with a non-Caucasian population. A multi-centric cross-sectional study was conducted in three sites in Colombia. Our study recruited trios of an ADHD proband, one sibling, and one parent. We used valid instruments for assessing parents and siblings. The sample included 223 siblings, an average age of 12.3 (SD 3.9), and 51.1% Females. The ADHD recurrence risk ratio (λ) was 12. The clinical factors mainly associated with the presence of ADHD, independent of sex and HPAd, were 1) Pregnancy and childbirth complications, 2) Delayed psychomotor development, 3) Temperament, and 4) Sleep disturbances. Our research showed that, independently of HPAd and the male sex, there were other clinical factors associated with ADHD and other psychiatric disorders in this population. These findings need to be replicated in similar populations globally.

Child- and parent-related determinants for out-of-home care in a nationwide population with neurodevelopmental disorders: a register-based Finnish birth cohort 1997 study

Neurodevelopmental disorders (NDDs) are among the most common health issues in childhood and adolescence. Psychiatric disorders are known to be overrepresented among children using child welfare services and placed in out-of-home care (OHC). Child- and parent-related determinants for OHC among a national population with NDDs were evaluated utilising longitudinal register data from the national Finnish Birth Cohort 1997 (n = 58,802) from birth to 18 years (1997-2015). The cohort members with NDDs (n = 5,143, 9% of total cohort) formed our study population. Based on their history of OHC, cohort members with NDD were categorised to OHC (n = 903) and non-OHC groups (n = 4,240). Of all cohort members with NDDs, 17.6% had a history of OHC. Within NDDs, a significant excess of ADHD diagnosis was observed in the OHC group compared to the non-OHC group (49% vs. 26%). The OHC group with NDDs was significantly characterised by having comorbid psychiatric diagnosis for conduct and oppositional disorders (adj. RR 2.21), substance use disorders (adj. RR 1.61) and depression and anxiety disorders (adj. RR 1.60). Of all parent-related determinants, the most prevailing in the OHC group compared to the non-OHC group, was social assistance received by parent (88% vs. 44.5%). The longer the period (in years) for received social assistance, the greater the likelihood for OHC (adj. RRs range from 2.41 for one year to 5.24 for over 4 years). Further, significantly associating determinants for OHC were parental psychiatric disorders (adj. RR 1.42) and parental death (adj. RR 1.23). Our findings from the population-based cohort of children and adolescents with NDDs highlight the importance of screening and assessment of family situation. Also, effective prevention and treating of comorbid psychiatric disorders, especially conduct and oppositional disorders is essential.

A longitudinal investigation of parental ratings and performance metrics for executive functioning and symptom severity in clinically referred youth with ADHD

There remains a knowledge gap concerning the persistence of attention deficit hyperactivity disorder (ADHD) over the longer term. The current study aimed to investigate the change in parent-rated, and performance-based metrics of executive functioning (EF) and the relationship between these EF metrics and ADHD symptoms in individuals with ADHD from childhood/adolescence to young adulthood. This was done by examining possible improvements in parent-rated EF and performance-based measures of inattention and inhibition over a three-year interval and their relationship to ADHD outcomes in 137 clinically referred youth with ADHD (mean age = 12.4 years, SD = 3.1). Participants' parents completed the Behavior Rating Inventory of Executive Function (BRIEF) and the Swanson-Nolan-Pelham Scale at baseline and follow-up. Participants completed the Conners' Continuous Performance Test, Version II (CPT II) at baseline and follow-up. Statistical analyses were performed with Linear Mixed Models. The sex- and age-standardized measures Commission and Hit reaction time (RT) subscales of the CPT II and parent-rated metacognitive, and behavior regulation composites of the BRIEF were largely stable between measuring points. CPT Omissions, Hit RT standard error (reaction time variability), and parent-rated ADHD symptom scores improved slightly. BRIEF composites and reaction time variability were related to ADHD symptoms using longitudinal data. Overall, behavioral aspects of EF, as observed by parents in the home context, appear to play a significant role in the trajectory of childhood ADHD.

DNA methylation epi-signature and biological age in attention deficit hyperactivity disorder patients

OBJECTIVE

Attention Deficit/Hyperactivity Disorder (ADHD) is a common behavioral syndrome that begins in childhood and affects 3.4% of children worldwide. Due to its etiological complexity, there are no consistent biomarkers for ADHD, however the high heritability presented by the disorder indicates a genetic/epigenetic influence. The main epigenetic mechanism is DNA methylation, a process with an important role in gene expression and in many psychiatric disorders. Thus, our study sought to identify epi-signatures biomarkers in 29 children clinically diagnosed with ADHD.

METHODS

After DNA extraction and bisulfite conversion, we performed methylation array experiment for differential methylation, ontological and biological age analysis.

RESULTS

The biological response in ADHD patients was not sufficient to determine a conclusive epi-signature in our study. However, our results highlighted the interaction of energy metabolism and oxidative stress pathways in ADHD patients detected by differential methylation patterns. Furthermore, we were able to identify a marginal association between the DNAmAge and ADHD.

CONCLUSION

Our study present new methylation biomarkers findings associated with energy metabolism and oxidative stress pathways, in addition to DNAmAge in ADHD patients. However, we propose that further multiethnic studies, with larger cohorts and including maternal conditions, are necessary to demonstrate a definitive association between ADHD and these methylation biomarkers.

ADHD co-morbidities: A review of implication of gene × environment effects with dopamine-related genes

ADHD is a major burden in adulthood, where co-morbid conditions such as depression, substance use disorder and obesity often dominate the clinical picture. ADHD has substantial shared heritability with other mental disorders, contributing to comorbidity. However, environmental risk factors exist but their interaction with genetic makeup, especially in relation to comorbid disorders, remains elusive. This review for the first time summarizes present knowledge on gene x environment (GxE) interactions regarding the dopamine system. Hitherto, mainly candidate (GxE) studies were performed, focusing on the genes DRD4, DAT1 and MAOA. Some evidence suggest that the variable number tandem repeats in DRD4 and MAOA may mediate GxE interactions in ADHD generally, and comorbid conditions specifically. Nevertheless, even for these genes, common variants are bound to suggest risk only in the context of gender and specific environments. For other polymorphisms, evidence is contradictory and less convincing. Particularly lacking are longitudinal studies testing the interaction of well-defined environmental with polygenic risk scores reflecting the dopamine system in its entirety.

Predictors of ADHD persistence in elementary school children who were assessed in earlier grades: A prospective cohort study from Istanbul, Turkey

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) is the most common neurodevelopmental disorders among school-age children worldwide. In a more recent follow-up study, Biederman et al. found that 78% of children diagnosed with ADHD between the ages of 6-17 years continued to have a full (35%) or a partial persistence after eleven years.

OBJECTIVE

In this study, it was aimed to identify the factors contributing to the persistence of ADHD symptoms in elemantary school children who were prospectively assessed both in their earlier and upper grades.

METHODS

The sample was drawn from a previous community-based study where ADHD symptoms in 3696 first/or second graders were examined in regard to their school entry age. Two years after, the families of the children that participated in the initial study were called by phone and invited to a re-evaluation session. Among those who were reached, 154 were consequently eligible and were assessed with Swanson, Nolan and Pelham questionnaire (SNAP-IV), Conners' rating scales (CRS) and the Kiddie schedule for affective disorders and schizophrenia (K-SADS).

RESULTS

Of the 154 children, 81 had been evaluated to have "probable ADHD" by the initial interview. Among these 81 children, 50 (61.7%) were indeed diagnosed with ADHD after two years. Initial scores of the teacher reported SNAP-IV inattention subscale predicted the ADHD diagnosis after two years, with an odds ratio of 1.0761 (p = 0.032, Wald: 4.595).

CONCLUSIONS

Our results suggest that high inattention symptom scores reported by the teacher in the earlier grades, might predict an ADHD diagnosis in upper grades.

Gray matter networks associated with attention and working memory deficit in ADHD across adolescence and adulthood

Attention-deficit/hyperactivity disorder (ADHD) is a childhood-onset neuropsychiatric disorder and may persist into adulthood. Working memory and attention deficits have been reported to persist from childhood to adulthood. How neuronal underpinnings of deficits differ across adolescence and adulthood is not clear. In this study, we investigated gray matter of two cohorts, 486 adults and 508 adolescents, each including participants from ADHD and healthy controls families. Two cohorts both presented significant attention and working memory deficits in individuals with ADHD. Independent component analysis was applied to the gray matter of each cohort, separately, to extract cohort-inherent networks. Then, we identified gray matter networks associated with inattention or working memory in each cohort, and projected them onto the other cohort for comparison. Two components in the inferior, middle/superior frontal regions identified in adults and one component in the insula and inferior frontal region identified in adolescents were significantly associated with working memory in both cohorts. One component in bilateral cerebellar tonsil and culmen identified in adults and one component in left cerebellar region identified in adolescents were significantly associated with inattention in both cohorts. All these components presented a significant or nominal level of gray matter reduction for ADHD participants in adolescents, but only one showed nominal reduction in adults. Our findings suggest although the gray matter reduction of these regions may not be indicative of persistency of ADHD, their persistent associations with inattention or working memory indicate an important role of these regions in the mechanism of persistence or remission of the disorder.

Genomic Variation, Evolvability, and the Paradox of Mental Illness

Twentieth-century genetics was hard put to explain the irregular behavior of neuropsychiatric disorders. Autism and schizophrenia defy a principle of natural selection; they are highly heritable but associated with low reproductive success. Nevertheless, they persist. The genetic origins of such conditions are confounded by the problem of variable expression, that is, when a given genetic aberration can lead to any one of several distinct disorders. Also, autism and schizophrenia occur on a spectrum of severity, from mild and subclinical cases to the overt and disabling. Such irregularities reflect the problem of missing heritability; although hundreds of genes may be associated with autism or schizophrenia, together they account for only a small proportion of cases. Techniques for higher resolution, genomewide analysis have begun to illuminate the irregular and unpredictable behavior of the human genome. Thus, the origins of neuropsychiatric disorders in particular and complex disease in general have been illuminated. The human genome is characterized by a high degree of structural and behavioral variability: DNA content variation, epistasis, stochasticity in gene expression, and epigenetic changes. These elements have grown more complex as evolution scaled the phylogenetic tree. They are especially pertinent to brain development and function. Genomic variability is a window on the origins of complex disease, neuropsychiatric disorders, and neurodevelopmental disorders in particular. Genomic variability, as it happens, is also the fuel of evolvability. The genomic events that presided over the evolution of the primate and hominid lineages are over-represented in patients with autism and schizophrenia, as well as intellectual disability and epilepsy. That the special qualities of the human genome that drove evolution might, in some way, contribute to neuropsychiatric disorders is a matter of no little interest.

An exploratory study of parent-child association in sensory modulation disorder involving ADHD-related symptoms

BACKGROUND

Sensory modulation disorder (SMD) and attention deficit hyperactivity disorder (ADHD) can co-occur and have overlapping symptoms, thus challenging practitioners. This study aimed to phenotypically explore parent-child associations in SMD, and the interplay between SMD- and ADHD-related symptoms in children with SMD and their parents.

METHODS

A cross-sectional study examined 70 parents (n = 35 mothers; n = 35 fathers) and their 35 children with and without SMD, aged 4-6 years. Parents completed care-giver reports: The Short Sensory Profile (SSP) and the ADHD Rating Scale, and self-reports: The Sensory Responsiveness Questionnaire (SRQ) and the ADHD Self-Report Scale (ASRS).

RESULTS

In the entire sample, we found a mother-offspring correlation between SSP and SRQ-Aversive scores (rs = -0.68; p < 0.001), but no such father-offspring correlation. However, when testing the ADHD Rating Scale and ASRS scores, we found correlations between mothers and offspring (rs = 0.54, p = 0.0008), and between fathers and offspring (rs = 0.34, p = 0.0494). In the entire sample a high correlation was found between SSP and ADHD Rating Scale scores (rs = -0.837, p < 0.001). We further found a high correlation in mothers (rs = 0.70, p < 0.001), and a moderate correlation in fathers (rs = 0.40, p = 0.019) between SRQ-Aversive and ASRS scores.

CONCLUSIONS

Novel findings reveal that parents-offspring heritability patterns differ in both these related conditions. These may contribute to familial practice and research.

Investigation of a developmental pathway from infant anger reactivity to childhood inhibitory control and ADHD symptoms: interactive effects of early maternal caregiving

BACKGROUND

ADHD is a neurodevelopmental disorder with a complex pathogenesis. Individual differences in temperamental reactivity - in particular, anger reactivity - are predictive of ADHD. The goal of this study was to examine the moderating (maternal caregiving behaviors; MCB) and mediating (inhibitory control) variables of reactivity using a 9-year multimethod prospective longitudinal design.

METHODS

Participants included 291 children (135 male; 156 female) who participated in a larger study of temperament and social-emotional development. Anger reactivity was assessed by observation of facial anger during an arm restraint task, and MCB were observed during a series of semi-structured mother-infant tasks, both at 9 months of age. Inhibitory control was assessed by performance on a go/no-go task at 5 years of age. ADHD symptoms were assessed by parent and teacher report questionnaires at 7 and 9 years, respectively.

RESULTS

Anger reactivity and poor inhibitory control were predictive of later ADHD symptoms. Results supported a moderated mediation model, in which the indirect effects of anger reactivity on ADHD symptoms through inhibitory control were conditional on quality of early MCB. Inhibitory control mediated the effect of anger reactivity on ADHD symptoms, but only among children exposed to lower-quality MCB.

CONCLUSIONS

Infant anger reactivity exerts a direct effect on later ADHD from infancy, suggesting anger reactivity as a very early indicator of ADHD risk. Higher-quality caregiving did not buffer against the direct risk of anger reactivity on ADHD but did buffer against the indirect risk by reducing the negative effect of anger reactivity on inhibitory control. Thus, in the developmental pathway from anger reactivity to ADHD, more sensitive, less intrusive parenting supports the development of protective mechanisms (i.e. inhibitory control) to remediate ADHD risk.

A network analysis approach to ADHD symptoms: More than the sum of its parts

In interpreting attention-deficit/hyperactivity disorder (ADHD) symptoms, categorical and dimensional approaches are commonly used. Both employ binary symptom counts which give equal weighting, with little attention to the combinations and relative contributions of individual symptoms. Alternatively, symptoms can be viewed as an interacting network, revealing the complex relationship between symptoms. Using a novel network modelling approach, this study explores the relationships between the 18 symptoms in the Diagnostic Statistical Manual (DSM-5) criteria and whether network measures are useful in predicting outcomes. Participants were from a community cohort, the Children’s Attention Project. DSM ADHD symptoms were recorded in a face-to-face structured parent interview for 146 medication naïve children with ADHD and 209 controls (aged 6–8 years). Analyses indicated that not all symptoms are equal. Frequencies of endorsement and configurations of symptoms varied, with certain symptoms playing a more important role within the ADHD symptom network. In total, 116,220 combinations of symptoms within a diagnosis of ADHD were identified, with 92% demonstrating a unique symptom configuration. Symptom association networks highlighted the relative importance of hyperactive/impulsive symptoms in the symptom network. In particular, the ‘motoric’-type symptoms as well as interrupts as a marker of impulsivity in the hyperactive domain, as well as loses things and does not follow instructions in the inattentive domain, had high measures of centrality. Centrality-measure weighted symptom counts showed significant association with clinical but not cognitive outcomes, however the relationships were not significantly stronger than symptom count alone. The finding may help to explain heterogeneity in the ADHD phenotype.

Child with multiple problems: Clinical complexity and uncertainty

When practising neurodevelopmental-behavioural paediatrics, responsibility rests with the individual clinician to interpret research evidence in their daily work. This is not necessarily an easy task. Children do not usually present with single, easily definable problems. Complexity and uncertainty are present from the outset due to heterogeneity inherent in the diagnoses available, patterns of comorbid problems and the unique challenges of each child's social context. This article examines the resulting clinical challenge and offers potential responses. Rather than striving to eliminate uncertainty with strategies such as extensive assessment, the goal is to work effectively and efficiently within the limits of what can be readily known. Suggested strategies address complexity by considering the components of what is going on (biological, developmental, transactional) as hypotheses shared within each child's system of care. These hypotheses can then be tested and revised systematically as further information arises along the journey of treatment and longitudinal care.

Bupropion for attention deficit hyperactivity disorder (ADHD) in adults

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a prevalent neurobiological condition, characterised by behavioral and cognitive symptoms such as inattention, impulsivity and/or excessive activity. The syndrome is commonly accompanied by psychiatric comorbidities and is associated with educational and occupational underachievement.Although psychostimulant medications are the mainstay of treatment for ADHD, not all adults respond optimally to, or can tolerate, these medicines. Thus, alternative non-stimulant treatment approaches for ADHD have been explored. One of these alternatives is bupropion, an aminoketone antidepressant and non-competitive antagonism of nicotinic acetylcholine receptors. Bupropion is registered for the treatment of depression and smoking cessation, but is also used off-label to treat ADHD.

OBJECTIVES

To assess the effects and safety of bupropion for the treatment of adults with ADHD.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and seven other databases in February 2017. We also searched three trials registers and three online theses portals. In addition, we checked references of included studies and contacted study authors to identify potentially relevant studies that were missed by our search.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that evaluated the effects (including adverse effects) of bupropion compared to placebo in adults with ADHD.

DATA COLLECTION AND ANALYSIS

Two review authors (WV, GB) independently screened records and extracted data using a data extraction sheet that we tested in a pilot study. We extracted all relevant data on study characteristics and results. We assessed risks of bias using the Cochrane 'Risk of bias' tool, and assessed the overall quality of evidence using the GRADE approach. We used a fixed-effect model to pool the results across studies.

MAIN RESULTS

We included six studies with a total of 438 participants. Five studies were conducted in the USA, and one in Iran. All studies evaluated a long-acting version of bupropion, with the dosage ranging from 150 mg up to 450 mg daily. Study intervention length varied from six to 10 weeks. Four studies explicitly excluded participants with psychiatric comorbidity and one study included only participants with opioid dependency. Four studies were funded by industry, but the impact of this on study results is unknown. Two studies were publicly funded and in one of these studies, the lead author was a consultant for several pharmaceutical companies and also received investigator-driven funding from two companies, however none of these companies manufacture bupropion. We judged none of the studies to be free of bias because for most risk of bias domains the study reports failed to provide sufficient details. Using the GRADE approach, we rated the overall quality of evidence as low. We downgraded the quality of the evidence because of serious risk of bias and serious imprecision due to small sample sizes.We found low-quality evidence that bupropion decreased the severity of ADHD symptoms (standardised mean difference -0.50, 95% confidence interval (CI) -0.86 to -0.15, 3 studies, 129 participants), and increased the proportion of participants achieving clinical improvement (risk ratio (RR) 1.50, 95% CI 1.13 to 1.99, 4 studies, 315 participants), and reporting an improvement on the Clinical Global Impression - Improvement scale (RR 1.78, 95% CI 1.27 to 2.50, 5 studies, 337 participants). There was low-quality evidence that the proportion of participants who withdrew due to any adverse effect was similar in the bupropion and placebo groups (RR 1.20, 95% CI 0.35 to 4.10, 3 studies, 253 participants). The results were very similar when using a random-effects model and when we analysed only studies that excluded participants with a psychiatric comorbidity.

AUTHORS' CONCLUSIONS

The findings of this review, which compared bupropion to placebo for adult ADHD, indicate a possible benefit of bupropion. We found low-quality evidence that bupropion decreased the severity of ADHD symptoms and moderately increased the proportion of participants achieving a significant clinical improvement in ADHD symptoms. Furthermore, we found low-quality evidence that the tolerability of bupropion is similar to that of placebo. In the pharmacological treatment of adults with ADHD, extended- or sustained-release bupropion may be an alternative to stimulants. The low-quality evidence indicates uncertainty with respect to the pooled effect estimates. Further research is very likely to change these estimates. More research is needed to reach more definite conclusions as well as clarifying the optimal target population for this medicine. Treatment response remains to be reported in a DSM5-diagnosed population. There is also a lack of knowledge on long-term outcomes.

Conceptualising compensation in neurodevelopmental disorders: Reflections from autism spectrum disorder

Within research into neurodevelopmental disorders, little is known about the mechanisms underpinning changes in symptom severity across development. When the behavioural presentation of a condition improves/symptoms lessen, this may be because core underlying atypicalities in cognition/neural function have ameliorated. An alternative possibility is 'compensation'; that the behavioural presentation appears improved, despite persisting deficits at cognitive and/or neurobiological levels. There is, however, currently no agreed technical definition of compensation or its behavioural, cognitive and neural characteristics. Furthermore, its workings in neurodevelopmental disorders have not been studied directly. Here, we review current evidence for compensation in neurodevelopmental disorders, using Autism Spectrum Disorder as an example, in order to move towards a better conceptualisation of the construct. We propose a transdiagnostic framework, where compensation represents the processes responsible for an observed mismatch between behaviour and underlying cognition in a neurodevelopmental disorder, at any point in development. Further, we explore potential cognitive and neural mechanisms driving compensation and discuss the broader relevance of the concept within research and clinical settings.

Attention deficit hyperactivity disorder may be a highly inflammation and immune-associated disease (Review)

Attention deficit hyperactivity disorder (ADHD) is a common behavioral disorder. Previous research has indicated that genetic factors, family education, environment and dietary habits are associated with ADHD. It has been determined that in China many children with ADHD also have allergic rhinitis or asthma. These children are more susceptible to the common cold or upper respiratory infections compared with normal healthy children. Additionally, the common cold or an upper respiratory infection may lead to disease recurrence or worsen the symptoms in these children. Previous studies have determined that ADHD may have a close association with allergic disease. Based on the clinically observed phenomenon and previous studies, it was hypothesized that ADHD is a high inflammation and immune‑associated disease. Therefore, the authors designed clinical and animal experiments to test this hypothesis in the future. Immune system disorders may be a novel part of the etiology of ADHD. The current report may have implications for future clinical practice.

Economic Burden of Attention-Deficit/Hyperactivity Disorder among Pediatric Patients in the United States

OBJECTIVES

To determine the adjusted incremental total costs (direct and indirect) for patients (aged 3-17 years) with attention-deficit/hyperactivity disorder (ADHD) and the differences in the adjusted incremental direct expenditures with respect to age groups (preschoolers, 0-5 years; children, 6-11 years; and adolescents, 12-17 years).

METHODS

The 2011 Medical Expenditure Panel Survey was used as the data source. The ADHD cohort consisted of patients aged 0 to 17 years with a diagnosis of ADHD, whereas the non-ADHD cohort consisted of subjects in the same age range without a diagnosis of ADHD. The annual incremental total cost of ADHD is composed of the incremental direct expenditures and indirect costs. A two-part model with a logistic regression (first part) and a generalized linear model (second part) was used to estimate the incremental costs of ADHD while controlling for patient characteristics and access-to-care variables.

RESULTS

The 2011 Medical Expenditure Panel Survey database included 9108 individuals aged 0 to 17 years, with 458 (5.0%) having an ADHD diagnosis. The ADHD cohort was 4.90 times more likely (95% confidence interval [CI] 2.97-8.08; P < 0.001) than the non-ADHD cohort to have an expenditure of at least $1, and among those with positive expenditures, the ADHD cohort had 58.4% higher expenditures than the non-ADHD cohort (P < 0.001). The estimated adjusted annual total incremental cost of ADHD was $949.24 (95% CI $593.30-$1305.18; P < 0.001). The adjusted annual incremental total direct expenditure for ADHD was higher among preschoolers ($989.34; 95% CI $402.70-$1575.98; P = 0.001) than among adolescents ($894.94; 95% CI $428.16-$1361.71; P < 0.001) or children ($682.71; 95% CI $347.94-$1017.48; P < 0.001).

CONCLUSIONS

Early diagnosis and use of evidence-based treatments may address the substantial burden of ADHD.

Prefrontal and parietal correlates of cognitive control related to the adult outcome of attention-deficit/hyperactivity disorder diagnosed in childhood

The protracted and highly variable development of prefrontal cortex regions that support cognitive control has been purported to shape the adult outcome of attention-deficit/hyperactivity disorder (ADHD). This neurodevelopmental model was tested in a prospectively followed sample of 27 adult probands who were diagnosed with ADHD in childhood and 28 carefully matched comparison subjects aged 21-28 years. Probands were classified with persistent ADHD or remitted ADHD. Behavioral and neural responses to the Stimulus and Response Conflict Task (SRCT) performed during functional magnetic resonance imaging (fMRI) were compared in probands and comparison subjects and in probands with persistent and remitted ADHD. Response speed and accuracy for stimulus, response, and combined conflicts did not differ across groups. Orbitofrontal, inferior frontal and parietal activation was lower in probands than comparison subjects, but only for combined conflicts, when demand for cognitive control was highest. Reduced activation for combined conflicts in probands was almost wholly attributable to the persistence of ADHD; orbitofrontal, inferior frontal, anterior cingulate and parietal activation was lower in probands with persistent ADHD than both probands with remitted ADHD and comparison subjects, but did not differ between probands with remitted ADHD and comparison subjects. These data provide the first evidence that prefrontal and parietal activation during cognitive control parallels the adult outcome of ADHD diagnosed in childhood, with persistence of symptoms linked to reduced activation and symptom recovery associated with activation indistinguishable from adults with no history of ADHD.

Association Between Age of Beginning Primary School and Attention Deficit Hyperactivity Disorder

OBJECTIVE

In April 2012, the Turkish national education system was modified, and the compulsory school age of entry (first grade) was redefined as a minimum of 60 months and a maximum of 66 months (replacing the former minimum criterion of 72 months). In this study, we hypothesized that students starting school before 72 months (the previous age standard for the first grade) may experience (1) a greater number of symptoms of attention deficit hyperactivity disorder (ADHD) and (2) lower functioning in social, behavioral, and academic domains.

METHOD

We performed a cross-sectional community-based study in the first and second grades of all primary schools (4356 students) located in the Kadıköy county of Istanbul, Turkey. Teachers completed Swanson, Nolan, and Pelham version IV and Conners' Teacher's report forms for symptoms of ADHD, the Perceived Competence Scale for functioning, and a sociodemographic questionnaire.

RESULTS

Among first graders, the group that began primary school before the age of 72 months had a higher ADHD prevalence than both of the groups that began primary school between the ages of 72 to 77 months and 78 to 83 months (p < .001 for both groups). ADHD symptoms diminished and academic, social, and behavioral functioning improved with age for the first and second grade students.

CONCLUSION

The probability of displaying ADHD symptoms (and caseness) is greater among the "earlier" beginners, whereas the "conventional" classmates exhibited better academic, social, and behavioral functioning.

Intelligence profiles of Chinese school-aged boys with high-functioning ASD and ADHD

PURPOSE

This study aimed to explore the intelligence profiles of Chinese school-aged boys with high-functioning autism spectrum disorder (HFASD) and attention-deficit/hyperactivity disorder (ADHD). Additionally, differences in intelligence quotient (IQ) between the HFASD group and the ADHD group were examined.

PATIENTS AND METHODS

Thirty-two boys with HFASD, 58 boys with ADHD, and 39 typically developing (TD) boys aged 6-16 years participated in this study. The ADHD group was divided into subgroups: ADHD-I (predominantly inattentive) and ADHD-C (combined type). (The ADHD-H [hyperactive] group was excluded because of small sample size). The Wechsler Intelligence Scale for Children-IV Chinese version was administered to every participant, and the FSIQ (Full-Scale IQ) score was used as the measure of IQ.

RESULTS

Both boys with HFASD and ADHD (ADHD-I and ADHD-C) showed impairments in Processing Speed Index and FSIQ, as compared to the TD group. Lower Verbal Comprehension Index scores were found in the ASD and ADHD-I groups. Interestingly, Working Memory Index was only impaired in children with ADHD. Additionally, equivalent Perceptual Reasoning Index (PRI) scores were found among the HFASD, ADHD, and TD groups.

CONCLUSION

Results indicated that both children with ADHD and HFASD have difficulty in processing speed, which may be explained by these children having neurodevelopmental disorders. These results also indicated that working memory appears to only be impacted by having ADHD. Children with ASD are known to have language difficulties while children with ADHD typically display working memory deficits; thus, these findings were expected.

Stimulant use for ADHD and relative age in class among children in Israel

BACKGROUND

Diagnosis of children with attention-deficit/hyperactivity disorder (ADHD) is increasing. The present study sought to identify characteristics and medication treatment patterns of children with ADHD and compare them by relative age in class, sex, ethnicity, family size, sibling order, and other socioeconomic status, as well as find trends in disparity of pharmacotherapy.

METHODS

This study was based on data from 1 013 149 Clalit Health Services members aged 6-17 years during 2006-2011. Centrally acting sympathomimetic drug purchases were compared according to children's estimated relative age in class; youngest third (born August to November), middle third (born April to July), and oldest third (born December to March). Treatment trends were determined and compared according to sociodemographic and family-related factors.

RESULTS

The overall prevalence of stimulant use in the population was 2.6% in 2006 and 4.9% in 2011. The annual incidence of stimulant use increased from 0.75% to 1.36%, rising more sharply among children in the older age groups (≥12) than among younger ones. Moreover, the youngest third of children in class was more likely to use medication than the oldest third (risk ratio (RR) 1.17, confidence interval (CI) 1.12-1.23) or the middle third (RR 1.06, CI 1.01-1.11). Of the different ethnic sectors, incidence of stimulant use was highest among general Jewish (1.8% in 2011) and lowest among Arabs (0.37% in 2011).

CONCLUSIONS

The use of stimulant medication is growing among children in Israel. Although the overall use does not exceed the estimated prevalence of ADHD among children, the appropriateness of prescribing to the Israeli pediatric population, especially to the youngest children in class, may be questionable. Copyright © 2016 John Wiley & Sons, Ltd.

Comorbidity of ADHD and High-functioning Autism: A Pilot Study on the Utility of the Overflow Movements Measure

OBJECTIVES

Children with attention-deficit/hyperactivity disorder (ADHD) and high-functioning autism (HFA) commonly show neurological soft signs (NSS) and impairment in executive functioning (EF). Many children with HFA may experience ADHD-like symptoms, and the 2 disorders may be comorbid. Evaluating NSS and EF in drug-naive subjects with ADHD, HFA, and ADHD+HFA compared with healthy children may be critical in understanding and differentiating the biological substrates and cognitive phenotypes associated with these disorders. The goal of this study was to evaluate possible differences among these groups in motor and EF and the effects of comorbidity.

METHODS

Thirty-eight drug-naive patients (13 with ADHD, 13 with HFA, 12 with ADHD+HFA) and 13 healthy controls (HC) were evaluated on measures of planning, verbal working memory, and response inhibition. Evaluation of NSS involved 3 primary variables: overflow movements (OM), dysrhythmia, and speed of timed activities.

RESULTS

The group with ADHD and the group with HFA both showed impairment on measures of planning, response inhibition, and verbal working memory compared with the HC group. Moreover, the group with ADHD showed a greater number of NSS compared with the HC group, whereas the group with HFA showed greater dysrhythmia and slowness compared with the HC group. The group with ADHD+HFA showed deficits of planning and response inhibition and a greater number of NSS compared with the HC group. The group with ADHD+HFA showed greater impairment of planning compared with the other clinical groups and greater dysrhythmia compared with the group with ADHD.

CONCLUSION

According to our data, the OM measure revealed a gradient in which ADHD was at one extreme (more OM) and HFA at the other extreme (less OM), whereas ADHD+HFA showed a number of OM that fell in the middle between the numbers for the ADHD and HFA groups.

Intra-individual reaction time variability based on ex-Gaussian distribution as a potential endophenotype for attention-deficit/hyperactivity disorder

OBJECTIVE

Intra-individual variability in reaction time (IIV-RT), defined by standard deviation of RT (RTSD), is considered as an endophenotype for attention-deficit/hyperactivity disorder (ADHD). Ex-Gaussian distributions of RT, rather than RTSD, could better characterize moment-to-moment fluctuations in neuropsychological performance. However, data of response variability based on ex-Gaussian parameters as an endophenotypic candidate for ADHD are lacking.

METHOD

We assessed 411 adolescents with clinically diagnosed ADHD based on the DSM-IV-TR criteria as probands, 138 unaffected siblings, and 138 healthy controls. The output parameters, mu, sigma, and tau, of an ex-Gaussian RT distribution were derived from the Conners' continuous performance test. Multi-level models controlling for sex, age, comorbidity, and use of methylphenidate were applied.

RESULTS

Compared with unaffected siblings and controls, ADHD probands had elevated sigma value, omissions, commissions, and mean RT. Unaffected siblings formed an intermediate group in-between probands and controls in terms of tau value and RTSD. There was no between-group difference in mu value. Conforming to a context-dependent nature, unaffected siblings still had an intermediate tau value in-between probands and controls across different interstimulus intervals.

CONCLUSION

Our findings suggest IIV-RT represented by tau may be a potential endophenotype for inquiry into genetic underpinnings of ADHD in the context of heterogeneity.

[Attention deficit hyperactivity disorder]

Attention deficit hyperactivity disorder (ADHD) is one of the most common childhood psychiatric disorders and can persist into the adulthood. ADHD has important social, academic and occupational consequences. ADHD diagnosis is based on the fulfillment of several clinical criteria, which can vary depending on the diagnostic system used. The clinical presentation can show great between-patient variability and it has been related to a dysfunction in the fronto-striatal and meso-limbic circuits. Recent investigations support a model in which multiple genetic and environmental factors interact to create a neurobiological susceptibility to develop the disorder. However, no clear causal association has yet been identified. Although multimodal treatment including both pharmacological and psychosocial interventions is usually recommended, no convincing evidence exists to support this recommendation. Pharmacological treatment has fundamentally shown to improve ADHD symptoms in the short term, while efficacy data for psychosocial interventions are scarce and inconsistent. Yet, drug treatment is increasingly popular and the last 2 decades have witnessed a sharp increase in the prescription of anti-ADHD medications coinciding with the marketing of new drugs to treat ADHD.

Children's relative age in class and use of medication for ADHD: a Danish Nationwide Study

BACKGROUND

Previous studies from North America and Iceland have shown that the youngest children within a grade are up to twice as likely to be diagnosed and treated for attention-deficit/hyperactivity disorder (ADHD) compared with their older classmates. We aimed to investigate whether younger age in class is associated with an increased probability of being prescribed medication for ADHD among school-aged children in Denmark.

METHODS

We followed all Danish children between 2000 and 2012 from 1st through 6th grade (7-12 years). Among children who started school on their age-assigned grade level, we estimated the prevalence proportion ratio (PPR) of receiving ADHD medication between the youngest children in class (born in October-December) and the oldest in class (born in January-March), specified by grade level, calendar year and gender. As a sensitivity analysis, we added children not on their age-assigned grade level to the main calculations.

RESULTS

We identified 932,032 eligible children for the main analysis, of whom 17.3% were among the youngest and 26.5% among the oldest in class. In total, 1.2% eligible children filled at least one prescription for ADHD medication in 2000-2012. The average PPR over the study period was 1.08 (95% CI, 1.04-1.12) and remained stable across subgroups and sensitivity analyses. Overall, 40% of children born October-December had entered school a year after their age-assigned grade level.

CONCLUSIONS

Contrary to previous study results, we observed almost no relative age effect on medication use for ADHD among children in Denmark. We postulate that this may be due to the high proportion of relatively young children held back by 1 year in the Danish school system and/or a generally low prevalence of ADHD medication use in the country.

Human endogenous retroviruses and ADHD

OBJECTIVES

Several lines of evidences suggest that human endogenous retroviruses (HERVs) are implicated in the development of many complex diseases with a multifactorial aetiology and a strong heritability, such as neurological and psychiatric diseases. Attention deficit hyperactivity Disorder (ADHD) is a neurodevelopmental disorder that results from a complex interaction of environmental, biological and genetic factors. Our aim was to analyse the expression levels of three HERV families (HERV-H, K and W) in patients with ADHD.

METHODS

The expression of retroviral mRNAs from the three HERV families was evaluated in peripheral blood mononuclear cells (PBMCs) from 30 patients with ADHD and 30 healthy controls by quantitative RT-PCR.

RESULTS

The expression levels of HERV-H are significantly higher in patients with ADHD compared to healthy controls, while there are no differences in the expression levels of HERV-K and W.

CONCLUSIONS

Since the ADHD aetiology is due to a complex interaction of environmental, biological and genetic factors, HERVs may represent one link among these factors and clinical phenotype of ADHD. A future confirmation of HERV-H overexpression in a larger number of ADHD patients will make possible to identify it as a new parameter for this clinical condition, also contributing to deepen the study on the role of HERVs in the neurodevelopment diseases.

Sensory processing abilities of children with ADHD

OBJECTIVE

To assess and compare the sensory processing abilities of children with Attention Deficit/Hyperactivity Disorder (ADHD) and children without disabilities, and to analyze the relationship between sensory processing difficulties and behavioural symptoms presented by children with ADHD.

METHOD

Thirty-seven children with ADHD were compared with thirty-seven controls using a translated and adapted version of the "Sensory Profile" answered by the parents/caregivers. For the ADHD group, Sensory Profile scores were correlated to behavioural symptoms assessed using the Child Behaviour Check List (CBCL) and the Behavioural Teacher Rating Scale (EACI-P). The statistical analyses were conducted using the Mann Whitney test and Pearson correlation coefficients.

RESULTS

Children with ADHD showed significant impairments compared to the control group in sensory processing and modulation, as well as in behavioural and emotional responses as observed in 11 out of 14 sections and 6 out of 9 factors. Differences in all Sensory Profile response patterns were also observed between the two groups of children. Sensory Profile scores showed a moderately negative correlation with CBCL and EACI-P scores in the ADHD group.

CONCLUSION

These results indicate that children with ADHD may present sensory processing impairments, which may contribute to the inappropriate behavioural and learning responses displayed by children with ADHD. It also suggests the importance of understanding the sensory processing difficulties and its possible contribution to the ADHD symptomatology.

ADHD and functional somatic symptoms: structural equations of a conceptual model

AIMS

To examine the effect of anxiety and parental overprotection on functional somatic symptoms (FSS) in children with attention deficit hyperactivity disorder (ADHD).

METHOD

Seventy-six children and adolescents (aged 6-17) with ADHD and their parents completed a clinical interview about psychiatric and somatic symptoms. Parents also reported about parenting styles. Structural equation modeling (SEM) was used.

RESULTS

The generalized anxiety, overprotection, and specific phobia variables each had a direct effect on FSS.

CONCLUSIONS

Anxiety symptoms and parental overprotection may play a role in the development of FSS in children with ADHD. Further research is necessary to corroborate our findings.

Association between SYP with attention-deficit/hyperactivity disorder in Chinese Han subjects: differences among subtypes and genders

Dysfunction of neurotransmitters has been suggested to be involved in the etiology of attention-deficit/hyperactivity disorder (ADHD). Hence, genes encoding proteins involved in the vesicular release process of those neurotransmitters are attractive candidates in ADHD genetics. One of these genes is SYP, which encodes synaptophysin, a protein known to participate in regulating neurotransmitter release and synaptic plasticity. Several studies have reported an association between SYP and ADHD, but more work is needed to refine the association. In the present study, we attempt to investigate their association in Chinese Han subjects by family-based and case-control studies. Transmission disequilibrium tests (TDTs) in 1112 trios found significant association between SYP and the predominantly inattentive subtype (ADHD-I), especially for males with ADHD-I, both from single nucleotide polymorphism (SNP) and haplotypic analyses. Chi-square tests in 1682 ADHD probands and 957 comparison subjects indicated possible association of SYP with female ADHD and female ADHD-I. However, the associated alleles and haplotypes between males and females were reversed. In conclusion, our results suggested that SYP may be primarily associated with ADHD-I and its genetic mechanism may be gender-specific. Thus, it is necessary to take subtype and gender into account in ADHD genetic studies.

Outcomes of child psychiatric treatment

OBJECTIVE

The aim of this study was to investigate outcomes of child psychiatric outpatient treatment as usual and to identify outcome predictors, with special regard to attention-deficit/hyperactivity disorder (ADHD), mood disorder, obsessive-compulsive disorder and conduct disorder.

METHOD

Routinely collected data from 12 613 outpatients between July 2006 and January 2010 in Stockholm, Sweden were analysed. The outcome measure was change in Children's Global Assessment Scale (CGAS) ratings between first visit and case closure (∆CGAS).

RESULTS

CGAS improved during the course of treatment across all diagnostic groups, ranging from a mean change of 4 (mental retardation) to 16 (suicide attempts). ∆CGAS was two times higher in the mood disorder group compared with the ADHD group. In the mood disorder group, several psychotherapies were associated with better outcome but not medication. In the ADHD group, psychotherapeutic interventions were also associated with better outcome, but those who received treatment with central stimulants received less non-medical interventions.

CONCLUSION

Whereas the functional impairment and the level of improvement in mood disorder corresponded to previous efficacy studies, the ADHD patients were more impaired and improved less after treatment. This should prompt a critical discussion as to whether ADHD patients receive the best available treatment in CAMHS in Stockholm and elsewhere.

EEG improvements with antiepileptic drug treatment can show a high correlation with behavioral recovery in children with ADHD

We investigated the relationship between neuropsychological disturbance, assessed using the global assessment of functioning (GAF) and the ADHD-rating scale (ADHD-RS), paroxysmal EEG abnormalities, and treatment with valproate sodium (VPA) in children with both attention deficit hyperactivity disorder (ADHD) and paroxysmal abnormality (PA). Participants with ADHD but without obvious epilepsy were recruited between April 1, 2003 and March 31, 2008. Paroxysmal abnormality was scored by measuring the spike frequency. Of 46 children, 16 showed PA; 3 of the 16 were excluded because no follow-up EEG was available. The EEG improved with VPA treatment in 5 of 8 patients with frontal PA and 3 of 5 patients with rolandic PA. While 83.3% of the patients with improvements in both assessments had frontal PA, only 16.7% had rolandic PA. The patients with frontal PA showed a significantly higher correlation between PA frequency and improvement in ADHD-RS compared with those with rolandic PA. In this study of children with ADHD, EEG improvement with antiepileptic drug treatment showed a high correlation with behavioral improvements as shown by ADHD-RS and GAF scores. However, this was not a population-based study, and the relative importance of detecting and treating PA in ADHD has yet to be determined.

A systematic review of combination therapy with stimulants and atomoxetine for attention-deficit/hyperactivity disorder, including patient characteristics, treatment strategies, effectiveness, and tolerability

OBJECTIVE

The purpose of this article was to systematically review the literature on stimulant and atomoxetine combination therapy, in particular: 1) Characteristics of patients with attention-deficit/hyperactivity disorder (ADHD) given combination therapy, 2) treatment strategies used, 3) efficacy and effectiveness, and 4) safety and tolerability.

METHODS

Literature databases (MEDLINE(®), EMBASE, Cochrane Central Register of Controlled Trials, Science Citation Index Expanded, and SciVerse Scopus) were systematically searched using prespecified criteria. Publications describing stimulant and atomoxetine combination therapy in patients with ADHD or healthy volunteers were selected for review. Exclusion criteria were comorbid psychosis, bipolar disorder, epilepsy, or other psychiatric/neurologic diseases that could confound ADHD symptom assessment, or other concomitant medication(s) to treat ADHD symptoms.

RESULTS

Of the 16 publications included for review, 14 reported findings from 3 prospective studies (4 publications), 7 retrospective studies, and 3 narrative reviews/medication algorithms of patients with ADHD. The other two publications reported findings from two prospective studies of healthy volunteers. The main reason for prescribing combination therapy was inadequate response to previous treatment. In the studies of patients with ADHD, if reported, 1) most patients were children/adolescents and male, and had a combined ADHD subtype; 2) methylphenidate was most often used in combination with atomoxetine for treatment augmentation or switch; 3) ADHD symptom control was improved in some, but not all, patients; and 4) there were no serious adverse events.

CONCLUSIONS

Published evidence of the off-label use of stimulant and atomoxetine combination therapy is limited because of the small number of publications, heterogeneous study designs (there was only one prospective, randomized controlled trial), small sample sizes, and geographic bias. Existing evidence suggests, but does not confirm, that this drug combination may benefit some, but not all, patients who have tried several ADHD medications without success.

A Four- and Five-Factor Structural Model for Wechsler Tests

The purpose of this commentary is to focus on the clinical utility of the four- and five-factor structural models for the Wechsler Adult Intelligence Scale—Fourth Edition (WAIS-IV) and Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV). It provides a discussion of important considerations when evaluating the clinical utility of the four-factor and five-factor models of the WISC-IV and the WAIS-IV. Topics covered include psychometric issues, alignment with Cattell–Horn–Carroll (CHC) theory of cognitive abilities (CHC theory), the importance of conative factors, developmental considerations, effort, environmental factors, and variability between individuals. The discussion concludes with a specific review of the purposes of the current studies and the implications for clinical utility.

Psychoendocrine and psychoneuroimmunological mechanisms in the comorbidity of atopic eczema and attention deficit/hyperactivity disorder

Epidemiological data indicate that atopic eczema (AE) in infancy significantly increases the risk for attention deficit/hyperactivity disorder (ADHD) in later life. The underlying pathophysiological mechanisms of this comorbidity are unknown. We propose that the release of inflammatory cytokines caused by the allergic inflammation and/or elevated levels of psychological stress as a result of the chronic disease interfere with the maturation of prefrontal cortex regions and neurotransmitter systems involved ADHD pathology. Alternatively, increased stress levels in ADHD patients may trigger AE via neuroimmunological mechanisms. In a third model, AE and ADHD may be viewed as two separate disorders with one or more shared risk factors (e.g., genetics, prenatal stress) that increase the susceptibility for both disorders leading to the co-occurrence of AE and ADHD. Future investigation of these three models may lead to a better understanding of the mechanisms underlying the observed comorbidity between AE and ADHD and further, to targeted interdisciplinary primary prevention and treatment strategies.

Age, academic performance, and stimulant prescribing for ADHD: a nationwide cohort study

BACKGROUND

We evaluated whether younger age in class is associated with poorer academic performance and an increased risk of being prescribed stimulants for attention-deficit/hyperactivity disorder (ADHD).

METHODS

This was a nationwide population-based cohort study, linking data from national registries of prescribed drugs and standardized scholastic examinations. The study population comprised all children born in 1994-1996 who took standardized tests in Iceland at ages 9 and 12 (n = 11 785). We estimated risks of receiving low test scores (0-10th percentile) and being prescribed stimulants for ADHD. Comparisons were made according to children's relative age in class.

RESULTS

Mean test scores in mathematics and language arts were lowest among the youngest children in the fourth grade, although the gap attenuated in the seventh grade. Compared with the oldest third, those in the youngest third of class had an increased relative risk of receiving a low test score at age 9 for mathematics (1.9; 95% confidence interval [CI] 1.6-2.2) and language arts (1.8; 95% CI 1.6-2.1), whereas at age 12, the relative risk was 1.6 in both subjects. Children in the youngest third of class were 50% more likely (1.5; 95% CI 1.3-1.8) than those in the oldest third to be prescribed stimulants between ages 7 and 14.

CONCLUSIONS

Relative age among classmates affects children's academic performance into puberty, as well as their risk of being prescribed stimulants for ADHD. This should be taken into account when evaluating children's performance and behavior in school to prevent unnecessary stimulant treatment.

Attention-deficit/hyperactivity disorder in older adults: prevalence and possible connections to mild cognitive impairment

Attentional deficits are frequently seen in isolation as the presenting sign and symptom of neurodegenerative disease, manifest as mild cognitive impairment (MCI). Persistent ADHD in the geriatric population could well be misconstrued as MCI, leading to the incorrect assumption that such persons are succumbing to a neurodegenerative disease process. Alternatively, the molecular, neuroanatomic, or neurochemical abnormalities seen in ADHD may contribute to the development of de novo late life neurodegenerative disease. The present review examines the issue of causality vs confound regarding the association of ADHD with MCI, suggesting that both are tenable hypotheses.

Comorbid externalising behaviour in AD/HD: evidence for a distinct pathological entity in adolescence

While the profiling of subtypes of Attention Deficit Hyperactivity Disorder (AD/HD) have been the subject of considerable scrutiny, both psychometrically and psychophysiologically, little attention has been paid to the effect of diagnoses comorbid with AD/HD on such profiles. This is despite the greater than 80% prevalence of comorbidity under the DSM-IV-TR diagnostic definitions. Here we investigate the event related potential (ERP) and psychometric profiles of Controls, AD/HD, and comorbid AD/HD (particularly AD/HD+ODD/CD) groups on six neurocognitive tasks thought to probe the constructs of selective and sustained attention, response inhibition and executive function. Data from 29 parameters extracted from a child group (age range 6 to 12; 52 Controls and 64 AD/HD) and from an adolescent group (age range 13 to 17; 79 Controls and 88 AD/HD) were reduced via a Principal Components Analysis, the 6 significant eigenvectors then used as determinants of cluster membership via a Two-Step Cluster Analysis. Two clusters were found in the analysis of the adolescent age group - a cluster dominated by Control and AD/HD participants without comorbidity, while the second cluster was dominated by AD/HD participants with externalising comorbidity (largely oppositional defiant/conduct disorder ODD/CD). A similar segregation within the child age group was not found. Further analysis of these objectively determined clusters in terms of their clinical diagnoses indicates a significant effect of ODD/CD comorbidity on a concurrent AD/HD diagnosis. We conclude that comorbid externalising behaviour in AD/HD constitutes a distinct pathological entity in adolescence.

Training the brain: fact and fad in cognitive and behavioral remediation

Putatively safe and effective for improving cognitive performance in both health and disease, products purported to train the brain appeal to consumers and healthcare practitioners. In an increasingly health-centered society, these applications constitute a burgeoning commercial market. Sparse evidence coupled with lack of scientific rigor, however, leaves claims concerning the impact and duration of such brain training largely unsubstantiated. On the other hand, at least some scientific findings seem to support the effectiveness and sustainability of training for higher brain functions such as attention and working memory. In the present paper we provide a tectonic integration and synthesis of cognitive training approaches. Specifically, we sketch the relative merits and shortcomings of these programs, which often appeal to parents who must choose between side-effect-laden medication and other less conventional options. Here we examine how neuroplasticity allows the healthy as well the impaired to benefit from cognitive training programs. We evaluate the evidence and consider whether brain training can be a stand-alone treatment or an adjunct to pharmacotherapy, outline promising future prospects, and highlight what training outcomes are plausible in line with available data. Future research would determine whether the field of brain training realizes its potential to revolutionize education and rehabilitation or withers away engulfed in controversy.

[Mental retardation and ADHD]

Hyperactivity syndromes and disorders (ADHD and HKD) include the symptoms of overactivity, inattention, and impulsivity, which occur in many other mental disorders as well, including mental retardation (MR). It is not surprising that symptoms of ADHD occur significantly higher in children with learning disabilities. Dekker and Koot (2003) found a prevalence of 14.8 % for ADHD in Dutch children attending special schools, and Emerson (2003) reported rates of 8.7 % for HKD in children with global learning disability, representing a 10-fold increased risk compared to the prevalence of hyperactivity (0.9 %) in the general population sample. Yet only very few studies have been published concerning ADHD in children with mental retardation. Several features distinguish the diagnoses of ADHD and MR. In contrast to the limited knowledge about the differences and similarities of ADHD and MR, many studies considered stimulant medication as a pharmacological management strategy for children suffering from ADHD, MR, or both. According to these studies, psychostimulants may improve the target symptoms of hyperactivity, impulsivity, disinhibition, and inattention, albeit with caveats: ADHD symptoms in patients with MR may be less responsive to medical treatment than in patients without MR. Moreover, people with MR may be more susceptible to side effects.

Attention-deficit/hyperactivity disorder in childhood is associated with cognitive test profiles in the geriatric population but not with mild cognitive impairment or Alzheimer's disease

The frequency of ADHD in the aging population and its relationship to late-life cognitive decline has not been studied previously. To address this gap in our understanding, the Wender-Utah ADHD Rating scale (WURS) was administered to 310 geriatric subjects with cognitive status ranging from normal cognition to mild cognitive impairment to overt dementia. The frequency of WURS-positive ADHD in this sample was 4.4%. WURS scores were not related to cognitive diagnoses, but did show nonlinear associations with tasks requiring sustained attention. The frequency of ADHD appears stable across generations and does not appear to be associated with MCI or dementia diagnoses. The association of attentional processing deficits and WURS scores in geriatric subjects could suggest that such traits remain stable throughout life. Caution should be considered when interpreting cognitive test profiles in the aging population that exhibit signs and symptoms of ADHD, as attentional deficits may not necessarily imply the existence of an underlying neurodegenerative disease state.

Epigenetics in Developmental Disorder: ADHD and Endophenotypes

Heterogeneity in attention-deficit/hyperactivity disorder (ADHD), with complex interactive operations of genetic and environmental factors, is expressed in a variety of disorder manifestations: severity, co-morbidities of symptoms, and the effects of genes on phenotypes. Neurodevelopmental influences of genomic imprinting have set the stage for the structural-physiological variations that modulate the cognitive, affective, and pathophysiological domains of ADHD. The relative contributions of genetic and environmental factors provide rapidly proliferating insights into the developmental trajectory of the condition, both structurally and functionally. Parent-of-origin effects seem to support the notion that genetic risks for disease process debut often interact with the social environment, i.e., the parental environment in infants and young children. The notion of endophenotypes, markers of an underlying liability to the disorder, may facilitate detection of genetic risks relative to a complex clinical disorder. Simple genetic association has proven insufficient to explain the spectrum of ADHD. At a primary level of analysis, the consideration of epigenetic regulation of brain signalling mechanisms, dopamine, serotonin, and noradrenaline is examined. Neurotrophic factors that participate in the neurogenesis, survival, and functional maintenance of brain systems, are involved in neuroplasticity alterations underlying brain disorders, and are implicated in the genetic predisposition to ADHD, but not obviously, nor in a simple or straightforward fashion. In the context of intervention, genetic linkage studies of ADHD pharmacological intervention have demonstrated that associations have fitted the "drug response phenotype," rather than the disorder diagnosis. Despite conflicting evidence for the existence, or not, of genetic associations between disorder diagnosis and genes regulating the structure and function of neurotransmitters and brain-derived neurotrophic factor (BDNF), associations between symptoms-profiles endophenotypes and single nucleotide polymorphisms appear reassuring.

Attention-deficit/hyperactivity disorder: a shift toward resilience?

Children with attention-deficit/hyperactivity disorder (ADHD) present a concern across clinical, academic, and social domains. However, a subset of these children does fairly well symptomatically and functionally. This article employs a resilience framework to organize the research on factors that promote favorable outcomes in ADHD. A PubMed search was conducted using key words: resilience and ADHD. Of particular interest were articles focusing on modifiable protective factors, such as parenting and pharmacotherapy. There is consensus that genetics strongly contributes to the etiology of ADHD. Parental, peer, and environmental factors may interact with genes to moderate the developmental expression of ADHD. Pharmacotherapy research reveals that medications exert positive effects of modest magnitude in academic achievement, social functioning and quality of life. However, there is insufficient evidence to determine whether treatment can modify developmental outcomes. Efforts to strengthen family support along with access to health and educational resources may also optimize outcomes.

ADHD and genetic syndromes

A high rate of Attention Deficit/Hyperactivity Disorder (ADHD)-like characteristics has been reported in a wide variety of disorders including syndromes with known genetic causes. In this article, we review the genetic and the neurobiological links between ADHD symptoms and some genetic syndromes such as: Fragile X Syndrome, Neurofibromatosis 1, DiGeorge Syndrome, Tuberous Sclerosis Complex, Turner Syndrome, Williams Syndrome and Klinefelter Syndrome. Although each syndrome may arise from different genetic abnormalities with multiple molecular functions, the effects of these abnormalities may give rise to common effects downstream in the biological pathways or neural circuits, resulting in the presentation of ADHD symptoms. Early diagnosis of ADHD allows for earlier treatment, and has the potential for a better outcome in children with genetic syndromes.

Use of ADHD drugs in the Nordic countries: a population-based comparison study

OBJECTIVE

To compare national use of attention-deficit/hyperactivity disorder (ADHD) drugs between five Nordic countries.

METHOD

A population-based drug utilisation study based on nationwide prescription databases, covering in total 24 919 145 individuals in 2007. ADHD drugs defined according to the World Health Organization Anatomic Therapeutic Chemical classification system as centrally acting sympathomimetics (N06BA).

RESULTS

The 2007 prevalence of ADHD drug use among the total Nordic population was 2.76 per 1000 inhabitants, varying from 1.23 per 1000 in Finland to 12.46 per 1000 in Iceland. Adjusting for age, Icelanders were nearly five times more likely than Swedes to have used ADHD drugs (Prev.Ratio = 4.53, 95% CI: 4.38-4.69). Prevalence among boys (age 7-15) was fourfold the prevalence among girls (Prev.Ratio = 4.28, 95% CI: 3.70-4.96). The gender ratio was diminished among adults (age 21 +) (Prev.Ratio = 1.24, CI: 1.21-1.27).

CONCLUSION

A considerable national variation in use of ADHD drugs exists between the Nordic countries.

Body mass index of children with attention-deficit/hyperactivity disorder

An association between overweight and attention-deficit/hyperactivity disorder (ADHD) in children was previously suggested. We examined the prevalence of overweight, anthropometric changes, and the effect of methylphenidate treatment in 275 children with ADHD without neurological comorbidities and in controls. Data were extracted from medical charts, for up to 17 months of follow-up. Height, weight, body mass index, and their z scores did not differ between the ADHD and control groups. Prevalence of overweight and obesity was lower in the ADHD group compared with controls (19% vs 35%, P = .02, and 7% vs 16%, P = .05, respectively). During a follow-up of up to 17 months, no significant changes in height or body mass index z scores were found, including in a subgroup of overweight children. We conclude that compared with local controls, children with ADHD have rates of overweight and obesity that are lower, but that are similar to national estimates. Methylphenidate treatment did not significantly affect height, weight, or overweight status.

Influence of candidate genes on attention problems in children: a longitudinal study

Attention problems form one of the core characteristics of Attention-Deficit Hyperactive Disorder (ADHD), a multifactorial neurodevelopmental disorder. From twin research it is clear that genes play a considerable role in the etiology and in the stability of ADHD in childhood. Association studies have focused on genes involved in the dopaminergic and serotoninergic systems, but with inconclusive results. This study investigated the effect of 26 Single Nucleotide Polymorphisms (SNPs) in genes encoding for serotonin receptors 2A (HTR2A), Catechol-O-Methyltransferase (COMT), Tryptophane Hydroxylase type 2 (TPH2), and Brain Derived Neurotrophic Factor (BDNF). Attention problems (AP) were assessed by parental report at ages 3, 7, 10, and 12 years in more than 16,000 twin pairs. There were 1148 genotyped children with AP data. We developed a longitudinal framework to test the genetic association effect. Based on all phenotypic data, a longitudinal model was formulated with one latent factor loading on all AP measures over time. The broad heritability for the AP latent factor was 82%, and the latent factor explained around 55% of the total phenotypic variance. The association of SNPs with AP was then modeled at the level of this factor. None of the SNPs showed a significant association with AP. The lowest p-value was found for the rs6265 SNP in the BDNF gene (p = 0.035). Overall, our results suggest no evidence for a role of these genes in childhood AP.