Co-transmission of conduct problems with attention-deficit/hyperactivity disorder: familial evidence for a distinct 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.

Early risk factors for conduct problem trajectories from childhood to adolescence: the 2004 Pelotas (BRAZIL) Birth Cohort

Conduct problems are associated with an increased risk of a wide range of physical, mental, and social problems. However, there is still uncertainty about how early risk factors differentiate different developmental patterns of conduct problems and whether findings replicate across diverse social contexts. We aimed to identify developmental trajectories of conduct problems, and test early risk factors, in the 2004 Pelotas Birth Cohort in Brazil. Conduct problems were measured at ages 4, 6, 11, and 15 years from caregiver reports on the Child Behaviour Checklist (CBCL) and Strengths and Difficulties Questionnaire (SDQ). Conduct problem trajectories were estimated using group-based semi-parametric modeling (n = 3938). Multinomial logistic regression was used to examine associations between early risk factors and conduct problem trajectories. We identified four trajectories: three with elevated conduct problems, including early-onset persistent (n = 150; 3.8%), adolescence-onset (n = 286; 17.3%), and childhood-limited (n = 697; 17.7%), and one with low conduct problems (n = 2805; 71.2%). The three elevated conduct problem trajectories were associated with a wide range of sociodemographic risk factors, prenatal smoking, maternal mental health, harsh parenting, childhood trauma, and child neurodevelopmental risk factors. Early-onset persistent conduct problems were particularly associated with trauma, living without a father figure, and attention difficulties. The four trajectories of conduct problems from ages 4 to 15 years in this Brazilian cohort have similar longitudinal patterns to those identified in high-income countries. The results confirm previous longitudinal research and developmental taxonomic theories on the etiology of conduct problems in a Brazilian sample.

Neuroanatomical markers of familial risk in adolescents with conduct disorder and their unaffected relatives

BACKGROUND

Previous studies have reported brain structure abnormalities in conduct disorder (CD), but it is unclear whether these neuroanatomical alterations mediate the effects of familial (genetic and environmental) risk for CD. We investigated brain structure in adolescents with CD and their unaffected relatives (URs) to identify neuroanatomical markers of familial risk for CD.

METHODS

Forty-one adolescents with CD, 24 URs of CD probands, and 38 healthy controls (aged 12-18), underwent structural magnetic resonance imaging. We performed surface-based morphometry analyses, testing for group differences in cortical volume, thickness, surface area, and folding. We also assessed the volume of key subcortical structures.

RESULTS

The CD and UR groups both displayed structural alterations (lower surface area and folding) in left inferior parietal cortex compared with controls. In contrast, CD participants showed lower insula and pars opercularis volume than controls, and lower surface area and folding in these regions than controls and URs. The URs showed greater folding in rostral anterior cingulate and inferior temporal cortex than controls and greater medial orbitofrontal folding than CD participants. The surface area and volume differences were not significant when controlling for attention-deficit/hyperactivity disorder comorbidity. There were no group differences in subcortical volumes.

CONCLUSIONS

These findings suggest that alterations in inferior parietal cortical structure partly mediate the effects of familial risk for CD. These structural changes merit investigation as candidate endophenotypes for CD. Neuroanatomical changes in medial orbitofrontal and anterior cingulate cortex differentiated between URs and the other groups, potentially reflecting neural mechanisms of resilience to CD.

Genetics in the ADHD Clinic: How Can Genetic Testing Support the Current Clinical Practice?

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder with a childhood prevalence of 5%. In about two-thirds of the cases, ADHD symptoms persist into adulthood and often cause significant functional impairment. Based on the results of family and twin studies, the estimated heritability of ADHD approximates 80%, suggests a significant genetic component in the etiological background of the disorder; however, the potential genetic effects on disease risk, symptom severity, and persistence are unclear. This article provides a brief review of the genome-wide and candidate gene association studies with a focus on the clinical aspects, summarizing findings of ADHD disease risk, ADHD core symptoms as dimensional traits, and other traits frequently associated with ADHD, which may contribute to the susceptibility to other comorbid psychiatric disorders. Furthermore, neuropsychological impairment and measures from neuroimaging and electrophysiological paradigms, emerging as potential biomarkers, also provide a prominent target for molecular genetic studies, since they lie in the pathway from genes to behavior; therefore, they can contribute to the understanding of the underlying neurobiological mechanisms and the interindividual heterogeneity of clinical symptoms. Beyond the aforementioned aspects, throughout the review, we also give a brief summary of the genetic results, including polygenic risk scores that can potentially predict individual response to different treatment options and may offer a possibility for personalized treatment for the therapy of ADHD in the future.

Correlation research of susceptibility single nucleotide polymorphisms and the severity of clinical symptoms in attention deficit hyperactivity disorder

OBJECTIVE

To analyze the correlation between susceptibility single nucleotide polymorphisms (SNPs) and the severity of clinical symptoms in children with attention deficit hyperactivity disorder (ADHD), so as to supplement the clinical significance of gene polymorphism and increase our understanding of the association between genetic mutations and ADHD phenotypes.

METHODS

193 children with ADHD were included in our study from February 2017 to February 2020 in the Children's ADHD Clinic of the author's medical institution. 23 ADHD susceptibility SNPs were selected based on the literature, and multiple polymerase chain reaction (PCR) targeted capture sequencing technology was used for gene analysis. A series of ADHD-related questionnaires were used to reflect the severity of the disease, and the correlation between the SNPs of specific sites and the severity of clinical symptoms was evaluated. R software was used to search for independent risk factors by multivariate logistic regression and the "corplot" package was used for correlation analysis.

RESULTS

Among the 23 SNP loci of ADHD children, no mutation was detected in 6 loci, and 2 loci did not conform to Hardy-Weinberg equilibrium. Of the remaining 15 loci, there were 9 SNPs, rs2652511 (SLC6A3 locus), rs1410739 (OBI1-AS1 locus), rs3768046 (TIE1 locus), rs223508 (MANBA locus), rs2906457 (ST3GAL3 locus), rs4916723 (LINC00461 locus), rs9677504 (SPAG16 locus), rs1427829 (intron) and rs11210892 (intron), correlated with the severity of clinical symptoms of ADHD. Specifically, rs1410739 (OBI1-AS1 locus) was found to simultaneously affect conduct problems, control ability and abstract thinking ability of children with ADHD.

CONCLUSION

There were 9 SNPs significantly correlated with the severity of clinical symptoms in children with ADHD, and the rs1410739 (OBI1-AS1 locus) may provide a new direction for ADHD research. Our study builds on previous susceptibility research and further investigates the impact of a single SNP on the severity of clinical symptoms of ADHD. This can help improve the diagnosis, prognosis and treatment of ADHD.

Risk variants and polygenic architecture of disruptive behavior disorders in the context of attention-deficit/hyperactivity disorder

Attention-Deficit/Hyperactivity Disorder (ADHD) is a childhood psychiatric disorder often comorbid with disruptive behavior disorders (DBDs). Here, we report a GWAS meta-analysis of ADHD comorbid with DBDs (ADHD + DBDs) including 3802 cases and 31,305 controls. We identify three genome-wide significant loci on chromosomes 1, 7, and 11. A meta-analysis including a Chinese cohort supports that the locus on chromosome 11 is a strong risk locus for ADHD + DBDs across European and Chinese ancestries (rs7118422, P = 3.15×10⁻¹⁰, OR = 1.17). We find a higher SNP heritability for ADHD + DBDs (h²_SNP = 0.34) when compared to ADHD without DBDs (h²_SNP = 0.20), high genetic correlations between ADHD + DBDs and aggressive (r_g = 0.81) and anti-social behaviors (r_g = 0.82), and an increased burden (polygenic score) of variants associated with ADHD and aggression in ADHD + DBDs compared to ADHD without DBDs. Our results suggest an increased load of common risk variants in ADHD + DBDs compared to ADHD without DBDs, which in part can be explained by variants associated with aggressive behavior.

ADHD is often found to be comorbid with disruptive behavior disorders, but the genetic loci underlying this comorbidity are unknown. Here, the authors have performed a GWAS meta-analysis of ADHD with disruptive behavior disorders, finding three genome-wide significant loci in Europeans, and replicating one in a Chinese cohort.

Attention-Deficit/Hyperactivity Disorder (ADHD), antisociality and delinquent behavior over the lifespan

Attention-Deficit/Hyperactivity Disorder (ADHD) is closely linked to the development of conduct problems during socialization in early life and to an increased risk for antisocial activities and delinquency over the lifespan. The interaction between ADHD and common comorbid disorders like substance use disorders as well as changing environmental conditions could mediate the course of antisocial and delinquent behavior with increasing age. However, this complex interaction is only partially understood so far. This review presents current knowledge about the association of ADHD with antisociality and the development of delinquent behavior. Thereby, the relationships between ADHD, conduct disorder and antisocial personality disorder in offenders are discussed, as well as the impact of comorbid psychiatric disorders and psychosocial conditions on offending behavior. Also, treatment studies in offender populations with ADHD are presented. Although our understanding of the role of ADHD in the development of criminal behavior has substantially improved during the last two decades, more research is needed to further elucidate the mechanisms generating unfavorable outcomes and to engender adequate treatment strategies for this population at risk. Moreover, more attention is needed on children with conduct problems in order to avoid antisocial or delinquent behaviors over the lifespan.

Neurocognitive Deficits in Attention-Deficit/Hyperactivity Disorder With and Without Comorbid Oppositional Defiant Disorder

Objective: Oppositional Defiant Disorder (ODD) is highly prevalent in Attention-Deficit/Hyperactivity Disorder (ADHD) and may account for inconsistencies in findings on neurocognitive functioning in ADHD. Our aim was to assess cool and hot executive functioning (EF) and temporal processing in ADHD with and without comorbid ODD to elucidate the effects of comorbid ODD. Method: ADHD-only (n = 82), ADHD + ODD (n = 82), and controls (n = 82), with mean age 16 years (SD = 3.1), matched for age, gender, IQ, and ADHD type (clinical groups) were assessed on cool EF (inhibition, working memory), hot EF (reinforcement processing, emotion recognition), and temporal processing (time production and reproduction). Results: Individuals with ADHD + ODD showed abnormalities in inhibition, working memory, facial emotion recognition, and temporal processing, whereas individuals with ADHD-only were solely impaired in working memory and time production. Conclusion: Findings suggest that ODD carries a substantial part of the EF deficits observed in ADHD and contrast with current theories of neurocognitive impairments in ADHD.

Role of conduct problems in the relation between Attention-Deficit Hyperactivity disorder, substance use, and gaming

Known comorbidities for Attention-Deficit Hyperactivity Disorder (ADHD) include conduct problems, substance use disorder and gaming. Comorbidity with conduct problems may increase the risk for substance use disorder and gaming in individuals with ADHD. The aim of the study was to build a causal model of the relationships between ADHD and comorbid conduct problems, and alcohol, nicotine, and other substance use, and gaming habits, while accounting for age and sex. We used a state-of-the-art causal discovery algorithm to analyze a case-only sample of 362 ADHD-diagnosed individuals in the ages 12-24 years. We found that conduct problem severity mediates between ADHD severity and nicotine use, but not with more severe alcohol or substance use. More severe ADHD-inattentive symptoms lead to more severe gaming habits. Furthermore, our model suggests that ADHD severity has no influence on severity of alcohol or other drug use. Our findings suggest that ADHD severity is a risk factor for nicotine use, and that this effect is fully mediated by conduct problem severity. Finally, ADHD-inattentive severity was a risk factor for gaming, suggesting that gaming dependence has a different causal pathway than substance dependence and should be treated differently. By identifying these intervention points, our model can aid both researchers and clinicians.

Discovery of the first genome-wide significant risk loci for attention deficit/hyperactivity disorder

Attention deficit/hyperactivity disorder (ADHD) is a highly heritable childhood behavioral disorder affecting 5% of children and 2.5% of adults. Common genetic variants contribute substantially to ADHD susceptibility, but no variants have been robustly associated with ADHD. We report a genome-wide association meta-analysis of 20,183 individuals diagnosed with ADHD and 35,191 controls that identifies variants surpassing genome-wide significance in 12 independent loci, finding important new information about the underlying biology of ADHD. Associations are enriched in evolutionarily constrained genomic regions and loss-of-function intolerant genes and around brain-expressed regulatory marks. Analyses of three replication studies: a cohort of individuals diagnosed with ADHD, a self-reported ADHD sample and a meta-analysis of quantitative measures of ADHD symptoms in the population, support these findings while highlighting study-specific differences on genetic overlap with educational attainment. Strong concordance with GWAS of quantitative population measures of ADHD symptoms supports that clinical diagnosis of ADHD is an extreme expression of continuous heritable traits.

Discovery of the first genome-wide significant risk loci for attention deficit/hyperactivity disorder

Attention deficit/hyperactivity disorder (ADHD) is a highly heritable childhood behavioral disorder affecting 5% of children and 2.5% of adults. Common genetic variants contribute substantially to ADHD susceptibility, but no variants have been robustly associated with ADHD. We report a genome-wide association meta-analysis of 20,183 individuals diagnosed with ADHD and 35,191 controls that identifies variants surpassing genome-wide significance in 12 independent loci, finding important new information about the underlying biology of ADHD. Associations are enriched in evolutionarily constrained genomic regions and loss-of-function intolerant genes and around brain-expressed regulatory marks. Analyses of three replication studies: a cohort of individuals diagnosed with ADHD, a self-reported ADHD sample and a meta-analysis of quantitative measures of ADHD symptoms in the population, support these findings while highlighting study-specific differences on genetic overlap with educational attainment. Strong concordance with GWAS of quantitative population measures of ADHD symptoms supports that clinical diagnosis of ADHD is an extreme expression of continuous heritable traits.

Changes in serum levels of kynurenine metabolites in paediatric patients affected by ADHD

This study aims at determining serum levels of tryptophan and other metabolites of the kynurenine pathway in children with attention deficit hyperactivity disorder (ADHD) compared to healthy controls. Such metabolites interact with glutamate receptors in the central nervous system, potentially modulating mechanisms that are pivotal in ADHD and thus potentially representing peripheral biomarkers of the disorder. We measured serum levels of tryptophan and some metabolites of the kynurenine pathway in 102 children with ADHD and 62 healthy controls by liquid chromatography-tandem mass spectrometry (LC-MS/MS). As compared to healthy controls, children with ADHD showed a reduction in serum levels of anthranilic acid (-60%), kynurenic acid (-11.2%), and xanthurenic acid (-12.5%). In contrast, serum levels of tryptophan (+11.0%) and kynurenine (+48.6%) were significantly enhanced, and levels of quinolinic acid were unchanged in children with ADHD. In a logistic regression model, the presence of ADHD was predicted by low anthranilic acid and high tryptophan levels. These findings support the involvement of the kynurenine pathway in the pathophysiology of ADHD and suggest that anthranilic acid and tryptophan levels should be investigated as potential peripheral biomarker for ADHD.

Co-Occurrence of ODD and CD in Preschool Children With Symptoms of ADHD

OBJECTIVE

Patterns of co-occurrence between ADHD, Oppositional Defiant Disorder (ODD), and Conduct Disorder (CD) were examined in a sample of non-referred preschool children. ADHD subtypes and sex differences were also explored.

METHOD

Children aged 3.5 years ( n = 1,048) with high scores on ADHD characteristics were recruited from the Norwegian Mother and Child Cohort Study and clinically assessed, including a semi-structured psychiatric interview.

RESULTS

In children with ADHD, concurrent ODD was present more often than CD (31% vs. 10%), but having ADHD gave higher increase in the odds of CD than of ODD (ODD: odds ratio [OR] = 6.7, 95% confidence interval [CI] = [4.2, 10.8]; CD: OR = 17.6, 95% CI = [5.9, 52.9]). We found a greater proportion of children having the combined ADHD subtype as well as more severe inattentiveness among children with co-occurring CD compared with ODD. Sex differences were minor.

CONCLUSION

There are important differences in co-occurring patterns of ODD and CD in preschool children with ADHD.

Pharmacological Treatment of ADHD in Addicted Patients: What Does the Literature Tell Us?

LEARNING OBJECTIVES

After participating in this activity, learners should be better able to:• Evaluate pharmacologic treatment of attention deficit/hyperactivity disorder (ADHD) in patients with substance use disorder (SUD) • Assess the causes of the diminished efficacy of ADHD medication in patients with comorbid SUD OBJECTIVE: Substance use disorder (SUD) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur, and the presence of ADHD complicates the treatment of the addiction. Pharmacotherapy is a potent intervention in childhood and adult ADHD, but findings have been mixed in adolescent and adult ADHD patients with SUDs. This review focuses on several contributing factors and possible explanations, with implications both for future research and for clinical practice.

METHOD

This systematic review examined all randomized, placebo-controlled trials of pharmacotherapy for ADHD in adult and adolescent SUD patients.

RESULTS

The number of studies is limited, and several studies are hampered by qualitative flaws. The results, in general, are inconclusive for most medications studied, but more recent trials using psychostimulants in robust dosing have demonstrated significantly positive results.

CONCLUSION

In reviewing these trials, possible explanations relating to the particular characteristics and problems of this complex patient group are discussed. Several factors, including ADHD symptom severity, psychiatric comorbidity, persistent drug use, choice of medication, and concomitant psychosocial intervention, influence study results. Taking these factors into account may improve the likelihood of detecting significant effects in future research, as the recent positive trials have indicated, and may help in the appropriate selection of pharmacotherapy in clinical practice.

Variation in Latent Classes of Adult Attention-Deficit Hyperactivity Disorder by Sex and Environmental Adversity

OBJECTIVE

The findings of genetic, imaging and neuropsychological studies of attention-deficit hyperactivity disorder (ADHD) are mixed. To understand why this might be the case we use both dimensional and categorical symptom measurement to provide alternate and detailed perspectives of symptom expression.

METHOD

Interviewers collected ADHD, conduct problems (CP) and sociodemographic data from 3793 twins and their siblings aged 22 to 49 (M = 32.6). We estimate linear weighting of symptoms across ADHD and CP items. Latent class analyses and regression describe associations between measured variables, environmental risk factors and subsequent disadvantage. Additionally, the clinical relevance of each class was estimated.

RESULTS

Five classes were found for women and men; few symptoms, hyperactive-impulsive, CP, inattentive, combined symptoms with CP. Women within the inattentive class reported more symptoms and reduced emotional health when compared to men and to women within other latent classes. Women and men with combined ADHD symptoms reported comorbid conduct problems but those with either inattention or hyperactivity-impulsivity only did not.

CONCLUSION

The dual perspective of dimensional and categorical measurement of ADHD provides important detail about symptom variation across sex and with environmental covariates.

Association of respondent psychiatric comorbidity with family history of comorbidity: Results from the National Epidemiologic Survey on Alcohol and Related Conditions-III

OBJECTIVE

Substance use disorders and major psychiatric disorders are common, highly comorbid with each other, and familial. However, the extent to which comorbidity is itself familial remains unclear. The purpose of this study is to investigate associations between comorbidity among respondents with family history of comorbidity.

METHODS

We analyzed data from the National Epidemiologic Survey on Alcohol and Related Conditions-III to study the associations of family history (FH) of comorbidity among alcoholism, drug problems, depression, antisocial behavior, and anxiety disorders in parents and maternal and paternal grandparents with corresponding DSM-5 diagnostic comorbidity among respondents. We utilized multivariable multinomial logistic regression models controlling for age, sex, race, education, family income, marital status, and adverse childhood experiences (ACEs).

RESULTS

All comorbid associations of any two disorders with FH were statistically significant; almost all adjusted odds ratios (ORs) for respondent comorbidity in the presence of FH of the parallel comorbidity exceeded 10. ORs involving antisocial behavior in relatives and antisocial personality disorder in respondents were consistently larger than those for any other pairs of disorders. After further adjustment for ACEs, most patterns of association were similar but the ORs were reduced twofold to threefold. ACEs may be mediators in relationships between familial and respondent comorbidities.

CONCLUSION

Further investigations of relationships among familial comorbidity, ACEs, and respondents' diagnoses may improve understanding of comorbidity.

Which kindergarten children are at greatest risk for attention-deficit/hyperactivity and conduct disorder symptomatology as adolescents?

We sought to identify which kindergarten children are simultaneously at risk of moderate or severe symptomatology in both attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD) as adolescents. These risk factor estimates have not been previously available. We conducted multinomial logistic regression analyses of multiinformant ratings by the end of middle school of a population-based, longitudinal sample of children followed from kindergarten to eighth grade (N = 7,456). Kindergarten children from low SES households, those raised by mothers with depressive symptoms or experiencing emotional problems or substance abuse, or those who were punished by spanking were significantly more likely to later display severe levels of ADHD-CD symptomatology in eighth grade. Kindergarten children frequently engaging in ADHD-CD-type behaviors were more likely to later experience both moderate (covariate adjusted OR = 2.37) and severe (covariate adjusted OR = 3.63) ADHD-CD symptomatology. Low academic achievement uniquely increased the risk of both moderate and severe symptomatology (adjusted OR range = 1.7 to 2.24). The results should guide early screening and school-based intervention efforts for ADHD-CD. Reducing children's risk for adolescent ADHD-CD symptomatology may require remediating low behavioral and academic functioning by the end of kindergarten. When these 2 modifiable factors occur together they increase kindergarten children's odds of experiencing severe ADHD-CD symptomatology in eighth grade by a multiplicative factor of 8.1.

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.

Are all the 18 DSM-IV and DSM-5 criteria equally useful for diagnosing ADHD and predicting comorbid conduct problems?

In view of ICD-11 revision, we evaluate whether the 18 DSM-IV diagnostic items retained by DSM-5 could be further improved (i) in predicting ADHD 'caseness' and 'impairment' and (ii) discriminating ADHD without CD (ADHD - CD) cases from ADHD with CD (ADHD + CD) cases. In a multi-centre study sample consisting of 1497 ADHD probands and 291 unaffected subjects, 18 diagnostic items were examined for redundancy; then each item was evaluated for association with caseness, impairment and CD status using Classical Test Theory, Item-Response Theory and logistic regression methods. First, all 18 DSM-IV items contributed significantly and independently to the clinical diagnosis of ADHD. Second, not all the DSM-IV items carried equal weighting. "Often loses things", "forgetfulness" and "difficulty sustaining attention" mark severity for Inattentiveness (IA) items and "often unduly noisy", "exhibits a persistent pattern of restlessness", "leaves seat in class" and "often blurts out answers" for Hyperactivity/Impulsivity (HI) items. "Easily distracted", "inattentive to careless mistakes", "often interrupts" and "often fidgets" are associated with milder presentations. In the IA domain, "distracted" yields most information in the low-severity range of the latent trait, "careless" in the mid-severity range and "loses" in the high-severity range. In the HI domains, "interrupts" yields most information in the low-severity range and "motor" in the high-severity range. Third, all 18 items predicted impairment. Fourth, specific ADHD items are associated with ADHD + CD status. The DSM-IV diagnostic items were valid and not redundant; however, some carried more weight than others. All items were associated with impairment.

Attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a persistent neurodevelopmental disorder that affects 5% of children and adolescents and 2.5% of adults worldwide. Throughout an individual's lifetime, ADHD can increase the risk of other psychiatric disorders, educational and occupational failure, accidents, criminality, social disability and addictions. No single risk factor is necessary or sufficient to cause ADHD. In most cases ADHD arises from several genetic and environmental risk factors that each have a small individual effect and act together to increase susceptibility. The multifactorial causation of ADHD is consistent with the heterogeneity of the disorder, which is shown by its extensive psychiatric co-morbidity, its multiple domains of neurocognitive impairment and the wide range of structural and functional brain anomalies associated with it. The diagnosis of ADHD is reliable and valid when evaluated with standard criteria for psychiatric disorders. Rating scales and clinical interviews facilitate diagnosis and aid screening. The expression of symptoms varies as a function of patient developmental stage and social and academic contexts. Although there are no curative treatments for ADHD, evidenced-based treatments can markedly reduce its symptoms and associated impairments. For example, medications are efficacious and normally well tolerated, and various non-pharmacological approaches are also valuable. Ongoing clinical and neurobiological research holds the promise of advancing diagnostic and therapeutic approaches to ADHD. For an illustrated summary of this Primer, visit: http://go.nature.com/J6jiwl.

Using Sibling Designs to Understand Neurodevelopmental Disorders: From Genes and Environments to Prevention Programming

Neurodevelopmental disorders represent a broad class of childhood neurological conditions that have a significant bearing on the wellbeing of children, families, and communities. In this review, we draw on evidence from two common and widely studied neurodevelopmental disorders-autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD)-to demonstrate the utility of genetically informed sibling designs in uncovering the nature and pathogenesis of these conditions. Specifically, we examine how twin, recurrence risk, and infant prospective tracking studies have contributed to our understanding of genetic and environmental liabilities towards neurodevelopmental morbidity through their impact on neurocognitive processes and structural/functional neuroanatomy. It is suggested that the siblings of children with ASD and ADHD are at risk not only of clinically elevated problems in these areas, but also of subthreshold symptoms and/or subtle impairments in various neurocognitive skills and other domains of psychosocial health. Finally, we close with a discussion on the practical relevance of sibling designs and how these might be used in the service of early screening, prevention, and intervention efforts that aim to alleviate the negative downstream consequences associated with disorders of neurodevelopment.

The prevalence of psychopathology in siblings of children with mental health problems: a 20-year systematic review

While the importance of looking at the entire family system in the context of child and adolescent mental health is well recognised, siblings of children with mental health problems (MHPs) are often overlooked. The existing literature on the mental health of these siblings needs to be reviewed. A systematic search located publications from 1990 to 2011 in four electronic databases. Thirty-nine relevant studies reported data on the prevalence of psychopathology in siblings of target children with MHPs. Siblings of target children had higher rates of at least one type of psychopathology than comparison children. Risk of psychopathology varied across the type of MHP in the target child. Other covariates included sibling age and gender and parental psychopathology. Significant variations and limitations in methodology were found in the existing literature. Methodological guidelines for future studies are outlined. Implications for clinicians, parents, and for future research are discussed.

Parental psychopathology in families of children with attention-deficit/hyperactivity disorder and exposed to maternal smoking during pregnancy

BACKGROUND

Both genetic and environmental factors have been implicated in the etiology of attention-deficit/hyperactivity disorder (ADHD). We had previously suggested that exposure to maternal smoking during pregnancy (MSDP) may be a valid basis for delineating a distinct subtype of ADHD, where children exposed to MSDP present with a more severe clinical picture. Here, we examine the psychopathology of parents in this group, to better understand the etiology of ADHD.

METHODS

Using the Family Interview for Genetic Studies in a sample of 514 families of children with ADHD, we collected data pertaining to lifetime parental psychopathology. Families were stratified based on maternal smoking during the complete gestational period. The frequency of different disorders was compared using the χ2 statistic.

RESULTS

In the group where mothers smoked during pregnancy, both parents were significantly more likely to have antisocial personality disorder, and problems with alcohol and drug abuse. Mothers had a significantly higher frequency of major depressive disorder (MDD), while fathers showed a trend for both MDD and bipolar disorder.

CONCLUSIONS

Based on the pattern of psychopathology in parents of children exposed to MSDP, as well as earlier reports of the severe clinical, behavioral, and cognitive phenotype in these children, combined with the large body of epidemiological evidence, we propose that these children present a distinct subtype of ADHD with comorbid conduct disorder. Furthermore, we propose that MSDP may be a proxy measure to help delineate this subtype.

Psychiatric comorbidity in treatment-seeking substance use disorder patients with and without attention deficit hyperactivity disorder: results of the IASP study

AIMS

To determine comorbidity patterns in treatment-seeking substance use disorder (SUD) patients with and without adult attention deficit hyperactivity disorder (ADHD), with an emphasis on subgroups defined by ADHD subtype, taking into account differences related to gender and primary substance of abuse.

DESIGN

Data were obtained from the cross-sectional International ADHD in Substance use disorder Prevalence (IASP) study.

SETTING

Forty-seven centres of SUD treatment in 10 countries.

PARTICIPANTS

A total of 1205 treatment-seeking SUD patients.

MEASUREMENTS

Structured diagnostic assessments were used for all disorders: presence of ADHD was assessed with the Conners' Adult ADHD Diagnostic Interview for DSM-IV (CAADID), the presence of antisocial personality disorder (ASPD), major depression (MD) and (hypo)manic episode (HME) was assessed with the Mini International Neuropsychiatric Interview-Plus (MINI Plus), and the presence of borderline personality disorder (BPD) was assessed with the Structured Clinical Interview for DSM-IV Axis II (SCID II).

FINDINGS

The prevalence of DSM-IV adult ADHD in this SUD sample was 13.9%. ASPD [odds ratio (OR) = 2.8, 95% confidence interval (CI) = 1.8-4.2], BPD (OR = 7.0, 95% CI = 3.1-15.6 for alcohol; OR = 3.4, 95% CI = 1.8-6.4 for drugs), MD in patients with alcohol as primary substance of abuse (OR = 4.1, 95% CI = 2.1-7.8) and HME (OR = 4.3, 95% CI = 2.1-8.7) were all more prevalent in ADHD(+) compared with ADHD(-) patients (P < 0.001). These results also indicate increased levels of BPD and MD for alcohol compared with drugs as primary substance of abuse. Comorbidity patterns differed between ADHD subtypes with increased MD in the inattentive and combined subtype (P < 0.01), increased HME and ASPD in the hyperactive/impulsive (P < 0.01) and combined subtypes (P < 0.001) and increased BPD in all subtypes (P < 0.001) compared with SUD patients without ADHD. Seventy-five per cent of ADHD patients had at least one additional comorbid disorder compared with 37% of SUD patients without ADHD.

CONCLUSIONS

Treatment-seeking substance use disorder patients with attention deficit hyperactivity disorder are at a very high risk for additional externalizing disorders.

Attention deficit/hyperactivity disorders with co-existing substance use disorder is characterized by early antisocial behaviour and poor cognitive skills

BACKGROUND

Attention Deficit/Hyperactivity Disorder (ADHD) is associated with an increased risk of co-existing substance abuse. The Swedish legislation on compulsory healthcare can be applied to persons with severe substance abuse who can be treated involuntarily during a period of six months. This context enables a reliable clinical assessment of ADHD in individuals with severe substance use disorder (SUD).

METHODS

In the context of compulsory care for individuals with severe SUD, male patients were assessed for ADHD, co-morbid psychiatric symptoms, psychosocial background, treatment history, and cognition. The data from the ADHD/SUD group (n = 60) was compared with data from (1) a group of individuals with severe substance abuse without known ADHD (SUD group, n = 120), as well as (2) a group with ADHD from an outpatient psychiatric clinic (ADHD/Psych group, n = 107).

RESULTS

Compared to the general SUD group in compulsory care, the ADHD/SUD group had already been significantly more often in compulsory care during childhood or adolescence, as well as imprisoned more often as adults. The most common preferred abused substance in the ADHD/SUD group was stimulant drugs, while alcohol and benzodiazepine abuse was more usual in the general SUD group. Compared to the ADHD/Psych group, the ADHD/SUD group reported more ADHD symptoms during childhood and performed poorer on all tests of general intellectual ability and executive functions.

CONCLUSIONS

The clinical characteristics of the ADHD/SUD group differed from those of both the SUD group and the ADHD/Psych group in several respects, indicating that ADHD in combination with SUD is a particularly disabling condition. The combination of severe substance abuse, poor general cognitive ability, severe psychosocial problems, including indications of antisocial behaviour, and other co-existing psychiatric conditions should be considered in treatment planning for adults with ADHD and SUD.

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.

A small-scale randomized controlled trial of the self-help version of the New Forest Parent Training Programme for children with ADHD symptoms

The efficacy of a self-help parent training programme for children with attention deficit hyperactivity disorder (ADHD) was evaluated. The New Forest Parenting Programme Self-help (NFPP-SH) is a 6-week written self-help psychological intervention designed to treat childhood ADHD. Forty-three children were randomised to either NFPP-SH intervention or a waiting list control group. Outcomes were child ADHD symptoms measured using questionnaires and direct observation, self-reported parental mental health, parenting competence, and the quality of parent-child interaction. Measures of child symptoms and parental outcomes were assessed before and after the intervention. ADHD symptoms were reduced, and parental competence was increased by self-help intervention. Forty-five percent of intervention children showed clinically significant reductions in ADHD symptoms. Self-help intervention did not lead to improvements in parental mental health or parent-child interaction. Findings provide support for the efficacy of self-help intervention for a clinical sample of children with ADHD symptoms. Self-help may provide a potentially cost-effective method of increasing access to evidence-based interventions for clinical populations.

Can pediatric bipolar-I disorder be diagnosed in the context of posttraumatic stress disorder? A familial risk analysis

Despite ongoing concerns that traumatized children with severe symptoms of emotional dysregulation may be inappropriately receiving a diagnosis of pediatric bipolar-I (BP-I) disorder, this issue has not been adequately examined in the literature. Because both pediatric BP-I disorder and posttraumatic stress disorder (PTSD) are familial disorders, if children with both BP-I and PTSD were to be truly affected with BP-I disorder, their relatives would be at high risk for BP-I disorder. To this end, we compared patterns of familial aggregation of BP-I disorder in BP-I children with and without PTSD with age and sex matched controls. Participants were 236 youths with BP-I disorder and 136 controls of both sexes along with their siblings. Participants completed a large battery of measures designed to assess psychiatric disorders, psychosocial, educational, and cognitive parameters. Familial risk analysis revealed that relatives of BP-I probands with and without PTSD had similar elevated rates of BP-I disorder that significantly differed from those of relatives of controls. Pediatric BP-I disorder is similarly highly familial in probands with and without PTSD indicating that their co-occurrence is not due to diagnostic error.

High loading of polygenic risk for ADHD in children with comorbid aggression

OBJECTIVE Although attention deficit hyperactivity disorder (ADHD) is highly heritable, genome-wide association studies (GWAS) have not yet identified any common genetic variants that contribute to risk. There is evidence that aggression or conduct disorder in children with ADHD indexes higher genetic loading and clinical severity. The authors examine whether common genetic variants considered en masse as polygenic scores for ADHD are especially enriched in children with comorbid conduct disorder. METHOD Polygenic scores derived from an ADHD GWAS meta-analysis were calculated in an independent ADHD sample (452 case subjects, 5,081 comparison subjects). Multivariate logistic regression analyses were employed to compare polygenic scores in the ADHD and comparison groups and test for higher scores in ADHD case subjects with comorbid conduct disorder relative to comparison subjects and relative to those without comorbid conduct disorder. Association with symptom scores was tested using linear regression. RESULTS Polygenic risk for ADHD, derived from the meta-analysis, was higher in the independent ADHD group than in the comparison group. Polygenic score was significantly higher in ADHD case subjects with conduct disorder relative to ADHD case subjects without conduct disorder. ADHD polygenic score showed significant association with comorbid conduct disorder symptoms. This relationship was explained by the aggression items. CONCLUSIONS Common genetic variation is relevant to ADHD, especially in individuals with comorbid aggression. The findings suggest that the previously published ADHD GWAS meta-analysis contains weak but true associations with common variants, support for which falls below genome-wide significance levels. The findings also highlight the fact that aggression in ADHD indexes genetic as well as clinical severity.

Genome-wide association study of inattention and hyperactivity-impulsivity measured as quantitative traits

Genome-wide association studies (GWAS) of attention-deficit/hyperactivity disorder (ADHD) offer the benefit of a hypothesis-free approach to measuring the quantitative effect of genetic variants on affection status. Generally the findings of GWAS relying on ADHD status have been non-significant, but the one study using quantitative measures of symptoms found SLC9A9 and SLC6A1 were associated with inattention and hyperactivity-impulsivity. Accordingly, we performed a GWAS using quantitative measures of each ADHD subtype measured with the Strengths and Weaknesses of ADHD and Normal Behaviour (SWAN) scale in two community-based samples. This scale captures the full range of attention and kinetic behavior; from high levels of attention and appropriate activity to the inattention and hyperactivity-impulsivity associated with ADHD within two community-based samples. Our discovery sample comprised 1,851 participants (mean age = 22.8 years [4.8]; 50.6% female), while our replication sample comprised 155 participants (mean age = 26.3 years [3.1]; 68.4% females). Age, sex, age × sex, and age2 were included as covariates and the results from each sample were combined using meta-analysis, then analyzed with a gene-based test to estimate the combined effect of markers within genes. We compare our results with markers that have previously been found to have a strong association with ADHD symptoms. Neither the GWAS nor subsequent meta-analyses yielded genome-wide significant results; the strongest effect was observed at rs2110267 (4.62 × 10-7) for symptoms of hyperactivity-impulsivity. The strongest effect in the gene-based test was for GPR139 on symptoms of inattention (6.40 × 10-5). Replication of this study with larger samples will add to our understanding of the genetic etiology of ADHD.

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.

Genome-wide association study of motor coordination problems in ADHD identifies genes for brain and muscle function

OBJECTIVES

Motor coordination problems are frequent in children with attention deficit/hyperactivity disorder (ADHD). We performed a genome-wide association study to identify genes contributing to motor coordination problems, hypothesizing that the presence of such problems in children with ADHD may identify a sample of reduced genetic heterogeneity.

METHODS

Children with ADHD from the International Multicentre ADHD Genetic (IMAGE) study were evaluated with the Parental Account of Children's Symptoms. Genetic association testing was performed in PLINK on 890 probands with genome-wide genotyping data. Bioinformatics enrichment-analysis was performed on highly ranked findings. Further characterization of the findings was conducted in 313 Dutch IMAGE children using the Developmental Coordination Disorder Questionnaire (DCD-Q).

RESULTS

Although none of the findings reached genome-wide significance, bioinformatics analysis of the top-ranked findings revealed enrichment of genes for motor neuropathy and amyotrophic lateral sclerosis. Genes involved in neurite outgrowth and muscle function were also enriched. Among the highest ranked genes were MAP2K5, involved in restless legs syndrome, and CHD6, causing motor coordination problems in mice. Further characterization of these findings using DCD-Q subscales found nominal association for 15 SNPs.

CONCLUSIONS

Our findings provide clues about the aetiology of motor coordination problems, but replication studies in independent samples are necessary.

The impact of study design and diagnostic approach in a large multi-centre ADHD study. Part 1: ADHD symptom patterns

BACKGROUND

The International Multi-centre ADHD Genetics (IMAGE) project with 11 participating centres from 7 European countries and Israel has collected a large behavioural and genetic database for present and future research. Behavioural data were collected from 1068 probands with the combined type of attention deficit/hyperactivity disorder (ADHD-CT) and 1446 'unselected' siblings. The aim was to analyse the IMAGE sample with respect to demographic features (gender, age, family status, and recruiting centres) and psychopathological characteristics (diagnostic subtype, symptom frequencies, age at symptom detection, and comorbidities). A particular focus was on the effects of the study design and the diagnostic procedure on the homogeneity of the sample in terms of symptom-based behavioural data, and potential consequences for further analyses based on these data.

METHODS

Diagnosis was based on the Parental Account of Childhood Symptoms (PACS) interview and the DSM-IV items of the Conners' teacher questionnaire. Demographics of the full sample and the homogeneity of a subsample (all probands) were analysed by using robust statistical procedures which were adjusted for unequal sample sizes and skewed distributions. These procedures included multi-way analyses based on trimmed means and winsorised variances as well as bootstrapping.

RESULTS

Age and proband/sibling ratios differed between participating centres. There was no significant difference in the distribution of gender between centres. There was a significant interaction between age and centre for number of inattentive, but not number of hyperactive symptoms. Higher ADHD symptom frequencies were reported by parents than teachers. The diagnostic symptoms differed from each other in their frequencies. The face-to-face interview was more sensitive than the questionnaire. The differentiation between ADHD-CT probands and unaffected siblings was mainly due to differences in hyperactive/impulsive symptoms.

CONCLUSIONS

Despite a symptom-based standardized inclusion procedure according to DSM-IV criteria with defined symptom thresholds, centres may differ markedly in probands' ADHD symptom frequencies. Both the diagnostic procedure and the multi-centre design influence the behavioural characteristics of a sample and, thus, may bias statistical analyses, particularly in genetic or neurobehavioral studies.

Die Bedeutung von Ängstlichkeit für die Phänotypisierung dissozialer Störungen des Kindes- und Jugendalters

In den letzten Jahren wurden vermehrt neurobiologische Marker dissozialen Verhaltens bei Kindern mit hohem Risiko für einen ungünstigen Verlauf (so genannter early-starter Subtyp der Conduct disorder, CD nach DSM-IV) identifiziert. Trotz einer Fokussierung auf diese Subpopulation innerhalb eines sehr heterogenen Störungsbildes liegen bisher widersprüchliche Befunde vor. Es deutet sich an, dass die zunehmenden methodischen Möglichkeiten der Untersuchung biologischer Marker eine detaillierte Phänotypisierung der untersuchten Stichproben notwendig macht. Die vorliegende Übersichtsarbeit betont die Berücksichtigung komorbider Ängstlichkeit als ein potenziell wichtiges Differenzierungsmerkmal, welches zu einer konsistenteren Befundlage vor allem im Bereich neuroendokriner Studien beitragen könnte. Möglicherweise bestehen darüber hinaus auch Assoziationen zu neurostrukturellen und neurofunktionellen Veränderungen des Gehirns. Es wird weiter der Einfluss des Merkmals Ängstlichkeit auf aggressives Verhalten sowie auf die Prognose der Betroffenen aufgezeigt. Eine detaillierte psychometrische und neurobiologische Charakterisierung könnte dazu beitragen, die an dissozialen Entwicklungen beteiligten neurobiologischen Mechanismen besser zu verstehen und die Effektivität derzeitiger therapeutische Optionen zu steigern.

Predictability of oppositional defiant disorder and symptom dimensions in children and adolescents with ADHD combined type

BACKGROUND

Oppositional defiant disorder (ODD) is frequently co-occurring with attention deficit hyperactivity disorder (ADHD) in children and adolescents. Because ODD is a precursor of later conduct disorder (CD) and affective disorders, early diagnostic identification is warranted. Furthermore, the predictability of three recently confirmed ODD dimensions (ODD-irritable, ODD-headstrong and ODD-hurtful) may assist clinical decision making.

METHOD

Receiver-operating characteristic (ROC) analysis was used in order to test the diagnostic accuracy of the Conners' Parent Rating Scale revised (CPRS-R) and the parent version of the Strength and Difficulties Questionnaire (PSDQ) in the prediction of ODD in a transnational sample of 1093 subjects aged 5-17 years from the International Multicentre ADHD Genetics study. In a second step, the prediction of three ODD dimensions by the same parent rating scales was assessed by backward linear regression analyses.

RESULTS

ROC analyses showed adequate diagnostic accuracy of the CPRS-R and the PSDQ in predicting ODD in this ADHD sample. Furthermore, the three-dimensional structure of ODD was confirmed by confirmatory factor analysis and the CPRS-R emotional lability scale significantly predicted the ODD irritable dimension.

CONCLUSIONS

The PSDQ and the CPRS-R are both suitable screening instruments in the identification of ODD. The emotional lability scale of the CPRS-R is an adequate predictor of irritability in youth referred for ADHD.

Self-perception of self-regulatory skills in children with attention-deficit/hyperactivity disorder aged 8-10 years

Several studies have reported a characteristic "positive illusory bias" in the self-evaluation of children with ADHD. However, results are controversial. The aim of the present study was to investigate whether children with ADHD aged 8 to 10 years can rate their self-regulatory skills accurately when assessed with an age appropriate instrument. Twenty-seven children with ADHD and 27 matched normal control children completed the Self-rating Scale of Self-regulatory Function (SelfReg), a new rating scale that has been specifically designed for this age group. As expected, children with ADHD rated themselves significantly more dysfunctional than control children. In most domains, self-ratings of children with ADHD did not diverge from parent and teacher ratings to a greater extent than self-ratings of control children, although overall results indicated a moderate tendency toward a positive bias. When a cluster analysis based on discrepancies between children's and adults' evaluations was carried out, three groups with different self-rating patterns emerged: A "positive bias" group containing exclusively children with ADHD, a "negative bias" group containing both children with ADHD and control children, and the largest group of accurate self-raters which also included children from both diagnostic groups. It is concluded that overly positive self-judgments are not a ubiquitous finding in ADHD, but may be confined to a specific subgroup of children whose specific characteristics remain to be determined.

Contribution of LPHN3 to the genetic susceptibility to ADHD in adulthood: a replication study

Attention-deficit/hyperactivity disorder (ADHD) is a common and highly heritable developmental disorder characterized by a persistent impairing pattern of inattention and/or hyperactivity-impulsivity. Using families from a genetic isolate, the Paisa population from Colombia, and five independent datasets from four different populations (United States, Germany, Norway and Spain), a highly consistent association was recently reported between ADHD and the latrophilin 3 (LPHN3) gene, a brain-specific member of the LPHN subfamily of G-protein-coupled receptors that is expressed in ADHD-related regions, such as amygdala, caudate nucleus, cerebellum and cerebral cortex. To replicate the association between LPHN3 and ADHD in adults, we undertook a case-control association study in 334 adult patients with ADHD and 334 controls with 43 single nucleotide polymorphisms (SNPs) covering the LPNH3 gene. Single- and multiple-marker analyses showed additional evidence of association between LPHN3 and combined type ADHD in adulthood [P = 0.0019; df = 1; odds ratio (OR) = 1.82 (1.25-2.70) and P = 5.1e-05; df = 1; OR = 2.25 (1.52-3.34), respectively]. These results further support the LPHN3 contribution to combined type ADHD, and specifically to the persistent form of the disorder, and point at this new neuronal pathway as a common susceptibility factor for ADHD throughout the lifespan.

Zur Komorbidität von aggressivem Verhalten und ADHS

Bei Kindern und Jugendlichen treten aggressives Verhalten und ADHS häufig gemeinsam auf und führen vielfach zu erheblichen psychosozialen Belastungen. Durch eine Metaanalyse wird eine verlässliche Maßzahl zum komorbiden Auftreten von ADHS und aggressivem Verhalten bestimmt. Anhand der Datenbanken PsycINFO und Pubmed wurden Studien identifiziert, die neben den relevanten Suchbegriffen ausgewählte Einschlusskriterien erfüllten, unter anderem „Allgemeinbevölkerung“ und „strukturierte Interviewverfahren“. In die Berechnung gingen acht epidemiologische Studien ein (N = 29980). Die metaanalytische Betrachtung bestätigt die hohe Komorbidität von ADHS und aggressivem Verhalten mit einem mittleren Odds Ratio von 21. Dieses Ergebnis wird für die Ätiologie und den Krankheitsverlauf diskutiert. Relevante Schlussfolgerungen für Diagnostik und Therapie werden aufgezeigt.

Increased echogenicity of the substantia nigra in children and adolescents with attention-deficit/hyperactivity disorder

BACKGROUND

Recent neurobiological models on attention-deficit/hyperactivity disorder (ADHD) as well as findings from imaging studies suggest a crucial involvement of dopaminergic midbrain nuclei, especially the substantia nigra (SN), in the pathogenesis of ADHD symptoms. The current study aimed to investigate whether alterations in the sonographic features of the SN could serve as a biological marker in ADHD patients.

METHODS

The current study employed transcranial sonography in 29 children and adolescents with ADHD and 27 healthy control participants to assess midbrain abnormalities in ADHD.

RESULTS

The ADHD patients showed an increase in echogenic size of the SN that was correlated with symptoms of inattention, hyperactivity, and impulsivity but not oppositional or dissocial symptoms. Hyperechogenicity, defined as echogenic size above the 90th percentile in the control group, was present in 48% of ADHD patients.

CONCLUSIONS

Our findings indicate an increased vulnerability of the nigrostriatal system in ADHD. Transcranial sonography could be successfully used in the future to explore whether ADHD patients with distinct SN hyperechogenicity constitute a specific subgroup or whether hyperechogenicity relates functionally to differences in reward processing, learning, and motor function.

Does the cortisol response to stress mediate the link between expressed emotion and oppositional behavior in Attention-Deficit/Hyperactivity-Disorder (ADHD)?

Background

Expressed Emotions (EE) are associated with oppositional behavior (OPB) in children with Attention Deficit/Hyperactivity Disorder (ADHD). EE has been linked to altered stress responses in some disorders, but ADHD has not been studied. We test the hypothesis that OPB in ADHD is mediated by altered stress-related cortisol reactivity to EE.

Methods

Two groups of children (with/without ADHD) and their respective parents were randomly assigned to two different conditions with/without negative emotion and participated in an emotion provocation task. Parents' EE, their ratings of their children's OPB and their children's salivary cortisol levels were measured.

Results

Low parental warmth was associated with OPB in ADHD. High levels of parental EE elicited a larger cortisol response. Stress-related cortisol reactivity mediated the EE-OPB link for all children. This highlights the general importance of parent-child interactions on externalizing behavior problems.

Conclusion

High EE is a salient stressor for ADHD children that leads to increased levels of cortisol and OPB. The development of OPB might be mediated by the stress-response to high EE.

Attention deficit hyperactivity disorder in men and women newly committed to prison: clinical characteristics, psychiatric comorbidity, and quality of life

Attention deficit hyperactivity disorder (ADHD) is associated with comorbid psychiatric diagnoses and antisocial behaviors that contribute to criminality, yet studies of ADHD in offenders are few. The authors evaluate a random sample of 319 offenders using a version of the Mini International Neuropsychiatric Interview and Medical Outcome Survey Health Survey. ADHD was present in 68 subjects (21.3%). Offenders with ADHD were more likely to report problems with emotional and social functioning and to have higher suicide risk scores (p < .001). They also had higher rates of mood, anxiety, psychotic, and somatoform disorders. Antisocial and borderline personality disorders were also more common among offenders with ADHD. The authors conclude that ADHD is common in offenders and is associated with comorbid disorders, worse quality of life, and higher risk for suicidal behaviors. Its presence should alert prison staff that the offender is likely to require more intensive mental health services.

Phenotypic and measurement influences on heritability estimates in childhood ADHD

Twin studies described a strongly heritable component of attention-deficit/hyperactivity disorder (ADHD) in children and adolescents. However, findings varied considerably between studies. In addition, ADHD presents with a high rate of comorbid disorders and associated psychopathology. Therefore, this literature review reports findings from population-based twin studies regarding the influence of subtypes, assessment instruments, rater effects, sex differences, and comorbidity rates on ADHD heritability estimates. In addition, genetic effects on the persistence of ADHD are discussed. By reviewing relevant factors influencing heritability estimates more homogeneous subtypes relevant for molecular genetic studies can be elicited. A systematic search of population-based twin studies in ADHD was performed, using the databases PubMed and PsycInfo. Results of family studies were added in case insufficient or contradictory findings were obtained in twin studies. Heritability estimates were strongly influenced by rater effects and assessment instruments. Inattentive and hyperactive-impulsive symptoms were likely influenced by common as well as specific genetic risk factors. Besides persistent ADHD, ADHD accompanied by symptoms of conduct or antisocial personality disorder might be another strongly genetically determined subtype, however, family environmental risk factors have also been established for this pattern of comorbidity.

The genetics of attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a complex neurodevelopmental disorder that almost certainly represents the common outcome of multiple causal pathways and it is now generally accepted that genetic factors make a significant contribution to these pathways. Behavioral studies suggest a heritability of approximately 0.76. While molecular genetic approaches have identified a range of potential candidate genes, it is now clear that the genetics of ADHD are characterized by a number of genes each of which makes a small but significant contribution to the overall risk. Several genome-wide linkage studies have been conducted and, although there are considerable differences in findings between studies, several regions have been supported across several studies (bin 16.4, 5p13, 11q22-25, 17p11). The contribution of several candidate genes has been supported by meta-analyses (DRD4, DRD5, DAT1, HTR1B and SNAP25). Genome-wide association scans are starting to appear but have not yet had sufficient power to produce conclusive results. Gene-environment interactions, which are as yet relatively understudied, are likely to be of importance in fully understanding the role of genes in ADHD and will be discussed.

Issues in the management of patients with complex attention-deficit hyperactivity disorder symptoms

Patients with attention-deficit hyperactivity disorder (ADHD) exhibit a wide range of symptoms related to functional impairment. Psychiatric comorbidities are highly prevalent among these patients, often emerging at an early age and persisting (or reoccurring) into adulthood. Among the most common types of comorbidities in children and adults are disruptive behaviour disorders such as oppositional defiant disorder and conduct disorder, mood disorders, anxiety disorders, and substance use disorders. The heterogeneous clinical presentation of ADHD, which also changes with maturation into adulthood, may often obscure the presence of psychiatric comorbidity. Co-occurring disorders frequently go undetected and lead to negative effects on psychosocial and long-term functional outcomes. As with uncomplicated ADHD, medication therapy combined with psychosocial interventions may be necessary. With comorbid disorders, two or more medications may be considered to appropriately manage both ADHD and the comorbid disorder. However, there are few studies that discuss combination medication treatments and there are no current US FDA-approved combined treatments for ADHD and comorbid conditions. This raises significant challenges and risks for poor tolerability and drug-drug interactions. Nevertheless, identification and appropriate treatment must be given a high priority for these highly vulnerable patients to derive optimal benefits from treatment.

A small-scale randomized controlled trial of the revised new forest parenting programme for preschoolers with attention deficit hyperactivity disorder

The revised new forest parenting programme (NFPP) is an 8-week psychological intervention designed to treat ADHD in preschool children by targeting, amongst other things, both underlying impairments in self-regulation and the quality of mother-child interactions. Forty-one children were randomized to either the revised NFPP or treatment as usual conditions. Outcomes were ADHD and ODD symptoms measured using questionnaires and direct observation, mothers' mental health and the quality of mother-child interactions. Effects of the revised NFPP on ADHD symptoms were large (effect size >1) and significant and effects persisted for 9 weeks post-intervention. Effects on ODD symptoms were less marked. There were no improvements in maternal mental health or parenting behavior during mother-child interaction although there was a drop in mothers' negative and an increase in their positive comments during a 5-min speech sample. The small-scale trial, although limited in power and generalizability, provides support for the efficacy of the revised NFPP. The findings need to be replicated in a larger more diverse sample.

Genetic risk for conduct disorder symptom subtypes in an ADHD sample: specificity to aggressive symptoms

OBJECTIVE

Recent studies have suggested an association between candidate genes (i.e., COMT, SLC6A4) and conduct disorder (CD). However, it is not clear if these relations extend to CD within the context of attention-deficit/hyperactivity disorder (ADHD). Also, it is uncertain whether the risk is specific to aggressive symptoms or is a risk for CD generally. The aim of this study was to examine the role of the COMT and SLC6A4 genes in the risk for CD and its symptomatic subtypes in the context of ADHD.

METHOD

We examined subjects with ADHD (n = 444, age range 6-55 years) aggregated across four completed studies. Psychiatric diagnoses were determined by structured interviews. We tested the association between genotype and the diagnosis of CD and aggressive and covert symptom counts.

RESULTS

There was no significant association between variations in functional polymorphisms of either the COMT gene or the SLC6A4 gene and the risk for CD. The COMT gene was associated with increased aggressive CD symptoms but not covert CD symptoms. The SLC6A4 gene was not associated with either symptom subtype.

CONCLUSIONS

These findings contribute to our understanding of the genetic basis of antisocial behavior in the ADHD population and provide additional support for the notion that aggressive and covert CD symptom subtypes are etiologically distinct.

Conduct disorder and ADHD: evaluation of conduct problems as a categorical and quantitative trait in the international multicentre ADHD genetics study

Attention-deficit/hyperactivity disorder (ADHD) is typically characterized by inattention, excessive motor activity, impulsivity, and distractibility. Individuals with ADHD have significant impairment in family and peer relations, academic functioning, and show high co-morbidity with a wide range of psychiatric disorders including oppositional defiant disorder (ODD), conduct disorder (CD), anxiety disorder, depression, substance abuse, and pervasive developmental disorder (PDD). Family studies suggest that ADHD + CD represents a specific subtype of the ADHD disorder with familial risk factors only partly overlapping with those of ADHD alone. We performed a hypothesis-free analysis of the GAIN-ADHD sample to identify markers and genes important in the development of conduct problems in a European cohort of individuals with ADHD. Using the Family-Based Association Test (FBAT) package we examined three measures of conduct problems in 1,043,963 autosomal markers. This study is part of a series of exploratory analyses to identify candidate genes that may be important in ADHD and ADHD-related traits, such as conduct problems. We did not find genome-wide statistical significance (P < 5 x 10(-7)) for any of the tested markers and the three conduct problem traits. Fifty-four markers reached strong GWA signals (P < 10(-5)). We discuss these findings in the context of putative candidate genes and the implications of these findings in the understanding of the etiology of ADHD + CD. We aimed to achieve insight into the genetic etiology of a trait using a hypothesis-free study design and were able to identify a number of biologically interesting markers and genes for follow-up studies.