Is Adult ADHD a Childhood-Onset Neurodevelopmental Disorder? Evidence From a Four-Decade Longitudinal Cohort Study

Associations between abuse/neglect and ADHD from childhood to young adulthood: A prospective nationally-representative twin study

Child maltreatment has consistently been found to be associated with attention deficit/hyperactivity disorder (ADHD). However, the robustness of this association and the direction of the link between maltreatment and ADHD remain unclear. We used data from the Environmental Risk (E-Risk) Longitudinal Twin Study, a cohort of 2232 British twins, to investigate the associations between exposure to abuse/neglect and ADHD in childhood and in young adulthood, and to test their robustness and specificity. We also aimed to test longitudinal associations between abuse/neglect and ADHD from childhood to young adulthood, controlling for confounders. Results indicated strong associations between abuse/neglect and ADHD in childhood and also in young adulthood. In childhood, the association was concentrated among children with comorbid conduct disorder. Longitudinal analyses showed that childhood ADHD predicted abuse/neglect in later years. This association was again concentrated among individuals with comorbid conduct disorder. Abuse/neglect in childhood was not associated with later ADHD in young adulthood after adjusting for childhood ADHD. Our study does not provide support of a causal link between child abuse/neglect and adult ADHD but highlights the possibility of a long-term effect of disruptive behaviors on the risk for experiencing abuse/neglect. These findings emphasize the need for clinicians treating people with ADHD, especially those with comorbid conduct disorder, to be aware of their increased risk for experiencing abuse/neglect. Interventions aimed at reducing risks of abuse/neglect should also focus on the environment of individuals with disruptive behaviors.

Association of Exposure to Diethylstilbestrol During Pregnancy With Multigenerational Neurodevelopmental Deficits

Importance

Animal evidence suggests that endocrine disruptors affect germline cells and neurodevelopment. However, to date, the third-generation neurodevelopmental outcomes in humans have not been examined.

Objective

To explore the potential consequences of exposure to diethylstilbestrol or DES across generations-specifically, third-generation neurodevelopment.

Design, Setting, and Participants

This cohort study uses self-reported health information, such as exposure to diethylstilbestrol during pregnancy and attention-deficit/hyperactivity disorder (ADHD) diagnosis, from 47 540 participants enrolled in the ongoing Nurses' Health Study II. The 3 generations analyzed in this study were the participants (F1 generation), their mothers (F0 generation), and their live-born children (F2 generation).

Main Outcomes and Measures

Participant- and mother-reported exposure to diethylstilbestrol during pregnancy and physician-diagnosed child ADHD.

Results

The total number of women included in this study was 47 540. Of the 47 540 F0 mothers, 861 (1.8%) used diethylstilbestrol and 46 679 (98.2%) did not while pregnant with the F1 participants. Use of diethylstylbestrol by F0 mothers was associated with an increased risk of ADHD among the F2 generation: 7.7% vs 5.2%, adjusted odds ratio (OR), 1.36 (95% CI, 1.10-1.67) and an OR of 1.63 (95% CI, 1.18-2.25) if diethylstilbestrol was taken during the first trimester of pregnancy. No effect modification was observed by the F2 children's sex.

Conclusions and Relevance

This study provides evidence that diethylstilbestrol exposure is associated with multigenerational neurodevelopmental deficits. The doses and potency level of environmental endocrine disruptors to which humans are exposed are lower than those of diethylstilbestrol, but the prevalence of such exposure and the possibility of cumulative action are potentially high and thus warrant consideration.

The economic consequences of attention-deficit hyperactivity disorder in the Scottish prison system

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) is highly prevalent amongst prison inmates and the criminal justice system (CJS) likely bears considerable costs for offenders with ADHD. We aimed to examine the relationship between ADHD and health-related quality of life (HRQoL) and quality-adjusted life years (QALY) amongst imprisoned adults; and to estimate the annual expenditure associated with ADHD status in prison.

METHODS

An observational study was performed in 2011-2013, at Porterfield Prison, Inverness, United Kingdom (UK). The all male sample included 390 adult prison inmates with capacity to consent and no history of moderate or severe intellectual disability. Participants were interviewed using the Diagnostic Interview for ADHD in Adults 2.0. The Health Utilities Index Mark 3 (HUI3) was used to measure health status, and to calculate attribute specific HRQoL scores and QALY. Health service utilisation was obtained through inspection of medical prison records. Inmates with ADHD were compared with inmates without ADHD.

RESULTS

Inmates with ADHD had significantly lower QALYs, with a clinically significant adjusted difference of 0.13. Psychiatric co-morbidity accounted for the variation of ADHD on the HUI3 emotion domain only. Medical costs for inmates with ADHD were significantly higher; and behaviour-related prison costs were similar to prisoners without ADHD, reflecting a low frequency of recorded critical incidents.

CONCLUSIONS

ADHD may directly contribute to adverse health and quality of life through cognitive and executive function deficits, and co-morbid disorders. The extrapolation of conservative cost estimates suggests that the financial burden of medical and behavior-related prison care for inmates with ADHD in the UK is approximately £11.7 million annually. The reported cost estimates are conservative as there is great variability in recorded critical incidents in prisons. In turn, for some prison establishments the prison care costs associated with prisoners with ADHD may be considerably greater.

Reduced prefrontal hemodynamic response in adult attention-deficit hyperactivity disorder as measured by near-infrared spectroscopy

AIM

Recent developments in near-infrared spectroscopy (NIRS) have enabled non-invasive clarification of brain functions in psychiatric disorders. In pediatric attention-deficit hyperactivity disorder (ADHD), reduced prefrontal hemodynamic responses have been observed with NIRS repeatedly. However, there are few studies of adult ADHD by multi-channel NIRS. Therefore, in this study, we used multi-channel NIRS to examine the characteristics of prefrontal hemodynamic responses during the Stroop Color-Word Task (SCWT) in adult ADHD patients and in age- and sex-matched control subjects.

METHODS

Twelve treatment-naïve adults with ADHD and 12 age- and sex-matched healthy control subjects participated in the present study after giving consent. We used 24-channel NIRS to measure the oxygenated hemoglobin (oxy-Hb) changes at the frontal lobes of participants during the SCWT. We compared the oxy-Hb changes between adults with ADHD and control subjects by t-tests with Bonferroni correction.

RESULTS

During the SCWT, the oxy-Hb changes observed in the ADHD group were significantly smaller than those in the control group in channels 11, 16, 18, 21, 22, 23, and 24, corresponding to the prefrontal cortex. At channels 16, 21, 23, and 24 of the ADHD group, there were negative correlations between the symptomatic severity and the oxy-Hb changes.

CONCLUSION

The present study suggests that adults with ADHD have reduced prefrontal hemodynamic response as measured by NIRS.

Prenatal exposure to bisphenol A and hyperactivity in children: a systematic review and meta-analysis

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) has increased in prevalence in the past decade. Studies attempting to identify a specific genetic component have not been able to account for much of the heritability of ADHD, indicating there may be gene-environment interactions underlying the disorder, including early exposure to environmental chemicals. Based on several relevant studies, we chose to examine bisphenol A (BPA) as a possible contributor to ADHD in humans. BPA is a widespread environmental chemical that has been shown to disrupt neurodevelopment in rodents and humans.

OBJECTIVES

Using the Office of Health Assessment and Translation (OHAT) framework, a systematic review and meta-analysis was designed to determine the relationship between early life exposure to BPA and hyperactivity, a key diagnostic criterion of ADHD.

DATA SOURCES

Searches of PubMed, Web of Science, and Toxline were completed for all literature to January 1, 2017.

STUDY ELIGIBILITY CRITERIA

For inclusion, the studies had to publish original data, be in the English language, include a measure of BPA exposure, and assess if BPA exposure affected hyperactive behaviors in mice, rats or humans. Exposure to BPA had to occur at <3 months of age for humans, up to postnatal day 35 for rats and up to postnatal day 40 for mice. Exposure could occur either gestationally (via maternal exposure) or directly to the offspring.

STUDY APPRAISAL AND SYNTHESIS METHODS

Studies were evaluated using the OHAT risk of bias tool. The effects in humans were assessed qualitatively. For rodents exposed to 20 μg/kg/day BPA, we evaluated the study findings in a random effects meta-analytical model.

RESULTS

A review of the literature identified 29 rodent and 3 human studies. A random effects meta-analysis showed significantly increased hyperactivity in male rodents. In humans, early BPA exposure was associated with hyperactivity in boys and girls.

LIMITATIONS, CONCLUSIONS, AND IMPLICATIONS OF KEY FINDINGS

We concluded that early life BPA exposure is a presumed human hazard for the development of hyperactivity. Possible limitations of this systematic review include deficiencies in author reporting, exclusion of some literature based on language, and insufficient similarity between human studies. SRs that result in hazard-based conclusions are the first step in assessing and mitigating risks. Given the widespread exposure of BPA and increasing diagnoses of ADHD, we recommend immediate actions to complete such risk analyses and take next steps for the protection of human health. In the meantime, precautionary measures should be taken to reduce exposure in pregnant women, infants and children. The present analysis also discusses potential mechanisms by which BPA affects hyperactivity, and the most effective avenues for future research.

SYSTEMATIC REVIEW REGISTRATION NUMBER

Not available.

Performance of the Adult ADHD Self-Report Scale-v1.1 in Adults with Major Depressive Disorder

Attention deficit/hyperactivity disorder (ADHD) is an under-recognized comorbid disorder among patients with mood disorders. ADHD is an independent risk factor for suicidal ideation and behavior and contributes to many aspects of impaired function in adults. Diagnosis of ADHD in Major Depressive Disorder (MDD) patients is challenging due to the overlap in cognitive symptoms between the two disorders. The ADHD Self-Report Scale, version 1.1 (ASRS-v1.1) is a widely used screening instrument for ADHD in adults but its accuracy has not been evaluated previously in treatment-seeking MDD patients. We administered the ASRS-v1.1 to 55 healthy controls and 40 adults with a primary psychiatric diagnosis of MDD who were participating in clinical research studies. ADHD diagnosis was assessed via structured interview with the adult ADHD module of the Mini International Neuropsychiatric Interview Plus version 6.0.0 (MINI) along with a psychiatrist’s assessment. Overall, full-syndrome ADHD was diagnosed in 12.5% of the MDD patients. MDD patients endorsed all 18 items of the ASRS-v1.1 more frequently than the healthy controls and the number of ASRS-v1.1 items endorsed correlated with levels of anxiety in the MDD patients. The ASRS-v1.1 demonstrated fair performance for identifying full syndrome DSM-IV ADHD diagnosis, with sensitivity 60%, specificity: 68.6%, positive predictive value 21.4%, negative predictive value 92.3% and total classification accuracy of 67.5%. Positive predictive value improved substantially when the ADHD criterion requiring symptom onset before age 7 was omitted. In adult MDD patients, a negative ASRS-v1.1 screen strongly suggests the absence of ADHD but positive screen results require careful evaluation to determine whether self-reported ADHD symptoms simply emerge from depression or whether comorbid ADHD is present.

A prospective longitudinal investigation of the (dis)continuity of mental health difficulties between mid- to late-childhood and the predictive role of familial factors

Understanding individual variation in the continuity of youth mental health difficulties is critical for identifying the factors that promote recovery or chronicity. This study establishes the proportion of children showing psychopathology at 9 years, whose pathology had either remitted or persisted at 13. It describes the socio-demographic and clinical profiles of these groups, and examines the factors in 9-year-olds' familial environments that predict longitudinal remission vs. persistence of psychopathology. The study utilised data from a prospective longitudinal study of 8568 Irish children. Child psychopathology was assessed using the Strengths and Difficulties Questionnaire (SDQ). Analysis established the rates of continuity of SDQ classifications between 9 and 13 years. Analysis also investigated the familial factors that predicted the remission vs. persistence of psychopathological symptoms, controlling for socio-demographic and child factors. Average SDQ scores improved between the ages of 9 and 13, F(1, 7292) = 276.52, p < 0.001, [Formula: see text] = 0.04. Of children classified Abnormal aged 9, 41.1% remained so classified at 13, 21.4% were reclassified Borderline, and 37.6% Normal. Demographic and child risk factors for persistence of pathology were maleness (β = -1.00, p = 0.001, CI = 0.20-0.67), one-carer households (β = -0.71, p = 0.04, CI = 0.25-0.97), poor physical health (β = -0.64, p = 0.03, CI = 0.30-0.92), and low cognitive ability (β = 0.61, p = 0.002, CI = 1.26-2.70). Controlling for these factors, the only familial variable at 9 years that predicted subsequent pathological persistence was caregiver depression (β = -0.07, p = 0.03, CI = 0.87-0.99). The analysis highlights substantial rates of psychopathological discontinuity in a community sample and identifies the children most at risk of chronic mental health problems. These results will inform the targeting of early interventions and distribution of clinical resources.

ADHD is associated with migraine: a systematic review and meta-analysis

An association between primary headaches and attention-deficit/hyperactivity disorder (ADHD) has long been suggested. Moreover, headache is regarded as a common side effect of stimulants, the most effective treatment for ADHD. So far, no systematic review has evaluated the potential association between ADHD and headache. We performed a systematic review of the literature and a meta-analysis of all reported studies on ADHD and primary headaches. Our analysis showed a positive association between ADHD and migraine (OR 1.322, 95% CI 1.018-1717, p value 0.036), but not with tension-type headache. There is a significant association between migraine and ADHD. The mechanisms underlying this association remain to be elucidated, warranting further studies.

The dopamine transporter role in psychiatric phenotypes

The dopamine transporter (DAT) is one of the most relevant and investigated neurotransmitter transporters. DAT is a plasma membrane protein which plays a homeostatic role, controlling both extracellular and intracellular concentrations of dopamine (DA). Since unbalanced DA levels are known to be involved in numerous mental disorders, a wealth of investigations has provided valuable insights concerning DAT role into normal brain functioning and pathological processes. Briefly, this extensive but non-systematic review discusses what is recently known about the role of SLC6A3 gene which encodes the dopamine transporter in psychiatric phenotypes. DAT protein, SLC6A3 gene, animal models, neuropsychology, and neuroimaging investigations are also concisely discussed. To conclude, current challenges are reviewed in order to provide perspectives for future studies.

Late-Onset ADHD Reconsidered With Comprehensive Repeated Assessments Between Ages 10 and 25

OBJECTIVE

Adolescents and young adults without childhood attention deficit hyperactivity disorder (ADHD) often present to clinics seeking stimulant medication for late-onset ADHD symptoms. Recent birth-cohort studies support the notion of late-onset ADHD, but these investigations are limited by relying on screening instruments to assess ADHD, not considering alternative causes of symptoms, or failing to obtain complete psychiatric histories. The authors address these limitations by examining psychiatric assessments administered longitudinally to the local normative comparison group of the Multimodal Treatment Study of ADHD.

METHOD

Individuals without childhood ADHD (N=239) were administered eight assessments from comparison baseline (mean age=9.89 years) to young adulthood (mean age=24.40 years). Diagnostic procedures utilized parent, teacher, and self-reports of ADHD symptoms, impairment, substance use, and other mental disorders, with consideration of symptom context and timing.

RESULTS

Approximately 95% of individuals who initially screened positive on symptom checklists were excluded from late-onset ADHD diagnosis. Among individuals with impairing late-onset ADHD symptoms, the most common reason for diagnostic exclusion was symptoms or impairment occurring exclusively in the context of heavy substance use. Most late-onset cases displayed onset in adolescence and an adolescence-limited presentation. There was no evidence for adult-onset ADHD independent of a complex psychiatric history.

CONCLUSIONS

Individuals seeking treatment for late-onset ADHD may be valid cases; however, more commonly, symptoms represent nonimpairing cognitive fluctuations, a comorbid disorder, or the cognitive effects of substance use. False positive late-onset ADHD cases are common without careful assessment. Clinicians should carefully assess impairment, psychiatric history, and substance use before treating potential late-onset cases.

A case for methodological overhaul and increased study of executive function in the domestic dog (Canis lupus familiaris)

Executive function (EF) allows for self-regulation of behavior including maintaining focus in the face of distraction, inhibiting behavior that is suboptimal or inappropriate in a given context, and updating the contents of working memory. While EF has been studied extensively in humans, it has only recently become a topic of research in the domestic dog. In this paper, I argue for increased study of dog EF by explaining how it might influence the owner-dog bond, human safety, and dog welfare, as well as reviewing the current literature dedicated to EF in dogs. In "EF and its Application to "Man's Best Friend" section, I briefly describe EF and how it is relevant to dog behavior. In "Previous investigations into EF in dogs" section, I provide a review of the literature pertaining to EF in dogs, specifically tasks used to assess abilities like inhibitory control, cognitive flexibility, and working memory capacity. In "Insights and limitations of previous studies" section, I consider limitations of existing studies that must be addressed in future research. Finally, in "Future directions" section, I propose future directions for meaningful research on EF in dogs.

How neuropsychology can inform our understanding of preschool ADHD: Clinical and research implications

Neuropsychological assessments in preschoolers have not received as much attention as in older children and adults. Attention-deficit/hyperactivity disorder (ADHD) is a common disorder that occurs in early childhood associated with poor academic and personal outcomes, such as learning and social difficulties. Preschoolers with ADHD may present cognitive deficits that are related with the ADHD symptoms of inattention, hyperactivity, and impulsivity, but may also interfere, beyond and above the ADHD symptoms, with everyday functioning. Most importantly, cognitive deficits in preschoolers seem to predict future ADHD symptoms. Yet, the practice of neuropsychological assessment in this age-group has been limited. The present selective review highlights the contribution of comprehensive neuropsychological assessments to the early identification of symptomatic preschoolers and to our understanding of the nature and developmental trajectory of ADHD.

Screening for attention-deficit/hyperactivity disorder in borderline personality disorder

BACKGROUND

A valid screening instrument is needed to detect attention-deficit/hyperactivity disorder (ADHD) in treatment-seeking borderline personality disorder (BPD) patients. We aimed to test the performance of the widely-used Adult ADHD Self-Report Scale v1.1 screener (ASRS-v1.1).

METHODS

317 BPD subjects were systematically assessed for comorbid ADHD and completed the ASRS-v1.1. 79 BPD patients also completed the Wender Utah Rating Scale (WURS-25).

RESULTS

The prevalence of adult ADHD was of 32.4%. The overall positive predictive value of the ASRS-v1.1 was of 38.5%, the negative predictive value 77.0%, the sensitivity 72.8%, and the specificity 43.9%. Combining WURS-25 and ASRS-v1.1 improved sensitivity to 81.8% and specificity to 59.6%.

LIMITATIONS

Cross-sectional study on treatment-seeking patients.

CONCLUSIONS

We found a high prevalence of ADHD using structured interviews. The ASRS-v1.1 was not a sensitive screener for identifying possible ADHD cases in a BPD population, with a high number of false positives. When combined with the WURS-25, it offered improved screening.

Treatment of adult ADHD: a clinical perspective

Adult attention deficit/hyperactivity disorder (ADHD) has moved from the blurred edge of clinical focus to clear recognition as a prevalent and significant disorder in its own right. It is a relatively common comorbidity which if identified and treated may open the door to better outcomes for hard-to-treat patients. Conversely, failure to identify and treat adult ADHD is linked to negative outcomes. The recognition of the importance of adult ADHD in a subset of our patients challenges us to overcome our anxiety about this diagnosis and prevent the societal marginalization of vulnerable patients. Adult ADHD responds well to integrated pharmacological and psychotherapeutic intervention. Its treatment responsiveness reduces disability and allows the comorbidity which is typically present to be addressed. Mastering this challenge can make the diagnosis and treatment of adult ADHD a rewarding experience.

International Consensus Statement on Screening, Diagnosis and Treatment of Substance Use Disorder Patients with Comorbid Attention Deficit/Hyperactivity Disorder

Adult attention deficit/hyperactivity disorder (ADHD) often co-occurs with substance use disorders (SUD) and is associated with early onset and more severe development of SUD and with reduced treatment effectiveness. Screening tools allow for a good recognition of possible ADHD in adults with SUD and should be used routinely, followed by an ADHD diagnostic process initiated as soon as possible. Simultaneous and integrated treatment of ADHD and SUD, using a combination of pharmaco- and psychotherapy, is recommended. Long-acting methylphenidate, extended-release amphetamines, and atomoxetine with up-titration to higher dosages may be considered in patients unresponsive to standard doses. This paper includes evidence- and consensus-based recommendations developed to provide guidance in the screening, diagnosis and treatment of patients with ADHD-SUD comorbidity.

Emotion dysregulation in attention-deficit/hyperactivity disorder and borderline personality disorder

There is ongoing debate on the overlap between Attention-Deficit/Hyperactivity Disorder (ADHD) and Borderline Personality Disorder (BPD), particularly regarding emotion dysregulation (ED). In this paper, we present a narrative review of the available evidence on the association of these two disorders from several standpoints. First, we discuss the unique and shared diagnostic criteria for ADHD and BPD, focusing particularly on ED. We consider the methodology of ecological momentary assessment and discuss why this approach could be an alternative and more accurate way to qualitatively distinguish between ADHD and BPD. We summarise key findings on the genetic and environmental risk factors for ADHD and BPD and the extent to which there are shared or unique aetiological and neurobiological risk factors. Finally, we discuss the clinical relevance of considering both disorders in the assessment of patients presenting with trait-like behavioural syndromes, distinguishing the two conditions and implications for treatment.

Attention Deficit Hyperactivity Disorder (ADHD): Controversy, Developmental Mechanisms, and Multiple Levels of Analysis

Controversy abounds regarding the symptom dimensions of attention problems, impulsivity, and hyperactivity, developmentally extreme and impairing levels of which compose the diagnostic category of attention deficit hyperactivity disorder (ADHD). I highlight causal factors, underlying mechanisms, developmental trajectories, and female manifestations of ADHD, integrating the psychobiological underpinnings of this syndrome with contextual factors related to its clinical presentation, impairments, and soaring increases in diagnosed prevalence. Indeed, despite strong heritability, ADHD is expressed via transactional patterns of influence linked to family-, school-, peer-, neighborhood-, and policy-related factors. Moreover, intervention strategies must take into account both pharmacologic and behavioral modalities if the goal is to enhance competencies, rather than symptom reduction per se. A comprehensive understanding of ADHD mandates multiple levels of analysis-spanning genes, neurotransmission, brain pathways, individual skill levels, family socialization, peer relationships, and educational and cultural forces-which must be integrated and synthesized to surpass reductionist accounts, reduce stigma, and maximize the impact of prevention- and intervention-related efforts.

Attending to adult ADHD: a review of the neurobiology behind adult ADHD

Background

Attention deficit hyperactivity disorder (ADHD) is a common disorder in childhood, which progresses to adulthood in about a fifth of cases. For various reasons, adult ADHD is a disorder not comprehensively assessed by psychiatrists, not least because the biological underpinnings are only recently being unmasked.

Aims

This selective review targets psychiatrists without a background in neuroscience and aims to describe the neurobiological basis of ADHD.

Methods

In total, 40 articles from a PubMed search were selected for inclusion based on sample population and methodology (neuroimaging studies). Studies focussing on adult participants were selected preferentially for inclusion. Seminal articles relevant to childhood populations were included for the purpose of understanding general concepts around ADHD.

Results

The neuropathology of ADHD is not rooted in a single anatomical area, but in multiple parallel and intersecting pathways, which have demonstrated impaired functional connectivity in ADHD brains. Dysfunction in executive function, reward processing, attention networks and default networks play major roles in the neuropathology of this condition. Biological findings vary between individuals, with some showing greater dysfunction at cortical levels and others at subcortical levels, which is in keeping with its clinical heterogeneity.

Conclusion

Improved symptomatology in adulthood is linked to a number of factors. Maturation of the prefrontal cortex in early adulthood contributes to symptom attenuation in many cases, meaning that individuals with cortical dysfunction are more likely to grow out of symptoms, whereas individuals with subcortical dysfunction may be less likely to do so. There is emerging evidence for a similar but distinct disorder arising de novo in adulthood.

Evidence of sexual dimorphism of HTR1B gene on major adult ADHD comorbidities

Attention-deficit/hyperactivity disorder (ADHD) is a very common psychiatric disorder across the life cycle and frequently presents comorbidities. Since ADHD is highly heritable, several studies have focused in the underlying genetic factors involved in its etiology. One of the major challenges in this search is the phenotypic heterogeneity, which could be partly attributable to the sexual dimorphism frequently seen in psychiatric disorders. Taking into account the well-known sexual dimorphic effect observed in serotonergic system characteristics, we differentially tested the influence of HTR1B SNPs (rs11568817, rs130058, rs6296 and rs13212041) on ADHD susceptibility and on its major comorbidities according to sex. The sample comprised 564 adults with ADHD diagnosed according to DSM-IV criteria and 635 controls. There was no association of any HTR1B SNPs tested in relation to ADHD susceptibility. As for the comorbidities evaluated, after correction for multiple tests, significant associations were observed for both rs11568817 and rs130058 with substance use disorders (P_corr = 0.009 and P_corr = 0.018, respectively) and for rs11568817 with nicotine dependence (P_corr = 0.025) in men with ADHD. In women with ADHD, the same rs11568817 was associated with generalized anxiety disorder (P_corr = 0.031). The observed effects of rs11568817 G allele presence conferring risk to either substance use disorders or generalized anxiety disorder according to sex, suggest an overall scenario where a higher transcriptional activity of HTR1B, resulting from the presence of this allele, is related to externalizing behaviors in men and internalizing behaviors in women. These results are consistent with and expand previous evidence of sexual dimorphism of the serotoninergic system.

Neurobiological support to the diagnosis of ADHD in stimulant-naïve adults: pattern recognition analyses of MRI data

OBJECTIVE

In adulthood, the diagnosis of attention-deficit/hyperactivity disorder (ADHD) has been subject of recent controversy. We searched for a neuroanatomical signature associated with ADHD spectrum symptoms in adults by applying, for the first time, machine learning-based pattern classification methods to structural MRI and diffusion tensor imaging (DTI) data obtained from stimulant-naïve adults with childhood-onset ADHD and healthy controls (HC).

METHOD

Sixty-seven ADHD patients and 66 HC underwent high-resolution T1-weighted and DTI acquisitions. A support vector machine (SVM) classifier with a non-linear kernel was applied on multimodal image features extracted on regions of interest placed across the whole brain.

RESULTS

The discrimination between a mixed-gender ADHD subgroup and individually matched HC (n = 58 each) yielded area-under-the-curve (AUC) and diagnostic accuracy (DA) values of up to 0.71% and 66% (P = 0.003) respectively. AUC and DA values increased to 0.74% and 74% (P = 0.0001) when analyses were restricted to males (52 ADHD vs. 44 HC).

CONCLUSION

Although not at the level of clinically definitive DA, the neuroanatomical signature identified herein may provide additional, objective information that could influence treatment decisions in adults with ADHD spectrum symptoms.

Genetic and environmental aspects in the association between attention-deficit hyperactivity disorder symptoms and binge-eating behavior in adults: a twin study

BACKGROUND

Prior research demonstrated that attention-deficit hyperactivity disorder (ADHD) is associated with binge-eating behavior, binge-eating disorder (BED), and bulimia nervosa (BN). The aim of this study was to investigate these associations in an adult twin population, and to determine the extent to which ADHD symptoms and binge-eating behavior share genetic and environmental factors.

METHODS

We used self-reports of current ADHD symptoms and lifetime binge-eating behavior and associated characteristics from a sample of over 18 000 adult twins aged 20-46 years, from the population-based Swedish Twin Registry. Mixed-effects logistic regression was used to examine the association between ADHD and lifetime binge-eating behavior, BED, and BN. Structural equation modeling was used in 13 773 female twins to determine the relative contribution of genetic and environmental factors to the association between ADHD symptoms and binge-eating behavior in female adult twins.

RESULTS

ADHD symptoms were significantly associated with lifetime binge-eating behavior, BED, and BN. The heritability estimate for current ADHD symptoms was 0.42 [95% confidence interval (CI) 0.41-0.44], and for lifetime binge-eating behavior 0.65 (95% CI 0.54-0.74). The genetic correlation was estimated as 0.35 (95% CI 0.25-0.46) and the covariance between ADHD and binge-eating behavior was primarily explained by genetic factors (91%). Non-shared environmental factors explained the remaining part of the covariance.

CONCLUSIONS

The association between adult ADHD symptoms and binge-eating behavior in females is largely explained by shared genetic risk factors.

Age-dependent effects of acute methylphenidate on amygdala reactivity in stimulant treatment-naive patients with Attention Deficit/Hyperactivity Disorder

In the present study, we investigate whether methylphenidate (MPH) affects emotional processing and whether this effect is modulated by age. We measured amygdala reactivity with functional Magnetic Resonance Imaging (fMRI) during processing of angry and fearful facial expressions in male stimulant treatment-naive patients with ADHD (N = 35 boys; N = 46 men) and 23 healthy control subjects (N = 11 boys; N = 12 men). In ADHD patients, we also measured amygdala reactivity 90min after an acute oral challenge with MPH (0.5mg/kg). Mean amygdala reactivity was analyzed for all subjects using a repeated measures analysis of variance (ANOVA). Whole-brain maps were analyzed for the patients only. At baseline, we found a age*diagnosis effect approaching significance (p = 0.05) in the right amygdala due to lower reactivity in children with Attention Deficit/Hyperactivity Disorder (ADHD) vs. controls (-31%), but higher reactivity in adults with ADHD vs. controls (+31%). MPH significantly reduced right amygdala reactivity in all patients, resulting in further reductions in children. In the left amygdala, reduction of amygdala reactivity was confined to adult ADHD patients whereas there was no change in children with ADHD. MPH-induced decrease of amygdala reactivity in adults might be a promising avenue for managing emotional dysregulation when replicated for chronic MPH treatment.

Late-Onset ADHD: Understanding the Evidence and Building Theoretical Frameworks

PURPOSE OF REVIEW

The traditional definition of Attention-Deficit/Hyperactivity Disorder (ADHD), assuming onset in childhood, has been challenged by evidence from four recent birth-cohort studies that reported most adults with ADHD lacked a childhood categorical ADHD diagnosis.

RECENT FINDINGS

Late onset of symptoms was evaluated in the long-term follow-up of the Multimodal Treatment study of ADHD (MTA). In most cases, other factors were present that discounted the late onset of ADHD symptoms and excluded the diagnosis of ADHD. We offer two theoretical frameworks for understanding the ADHD trajectory throughout the life cycle: (1) the complex phenotype model, and (2) the restricted phenotype model. We conclude that (a) late onset (after age 12) is a valid trajectory for ADHD symptoms, (b) the percentage of these cases with onset after adolescence is yet uncertain, and

Is adult-onset attention deficit/hyperactivity disorder frequent in clinical practice?

Recent population-based longitudinal studies concluded that most adults with attention deficit/hyperactivity disorder (ADHD) symptoms would not have a childhood history of ADHD, leading to the concept of adult-onset ADHD. In a large, well-characterized clinical population of 446 adults with a primary complaint of ADHD, we reported a low frequency of adult-onset ADHD (6.9%), being a primary isolated condition in 2.8%. They had less severe symptoms and tendencies for higher hypersomnolence disorder comorbidity than patients with typical childhood-onset ADHD. Our findings reinforce the requirement to exclude other disorders that might overlap with ADHD or mimic ADHD symptoms in adulthood onset patients.

Instrumental conditioning for food reinforcement in the spontaneously hypertensive rat model of attention deficit hyperactivity disorder

Background

The spontaneously hypertensive rat is thought to show good validity as a model of attention deficit hyperactivity disorder, in part because of impaired delayed reinforcement behaviour, corresponding to the dynamic developmental theory of the disorder. However, some previous studies may have been confounded use of fluid reward. Therefore, the objective of this study was to assess the spontaneously hypertensive rat and two comparison strains (Wistar and Wistar Kyoto) using a non-delayed food reinforcement paradigm in an attempt to advance knowledge of basic learnt behaviour in this strain, without potentially confounding reward sensitivity, which could impact on motivation to learn. Rats were trained on a fixed ratio 1 two choice discrimination schedule, extinction, reacquisition and reversal. We also tested non-reinforced spontaneous alternation to facilitate data interpretation.

Results

The spontaneously hypertensive rat displayed slower shaping and reduced on task activity during task acquisition, contrasting with previous results which indicate either enhanced responding and an impairment only when a delay is used; we suggest several reasons for this. In line with previous work, the same strain exhibited poor extinguishing of behaviour but were not impaired to the same extent on reversal of the discrimination. Finally, non-reinforced alternations on a Y-maze were also reduced in the spontaneously hypertensive rat.

Conclusions

In sum, the spontaneously hypertensive rat appear to show poor response inhibition in reinforced and non-reinforced contexts. However, impaired response inhibition was reduced during reversal when an opposite response produced food reward alongside presentation of the conditioned stimulus. We discuss the possibility of enhanced attribution of incentive salience to cues in this strain and highlight several points of caution for researchers conducting behavioural assessments using the spontaneously hypertensive rat and their associated comparison strains.

Electronic supplementary material

The online version of this article (10.1186/s13104-017-2857-5) contains supplementary material, which is available to authorized users.

Adult Attention-Deficit/Hyperactivity Disorder (ADHD) and Insomnia: an Update of the Literature

PURPOSE OF REVIEW

Insomnia is diagnosed when there is dissatisfaction with sleep quantity or quality. It has a prevalence in the general population ranging from 31 to 56%. Insomnia has previously been associated with adult attention-deficit/hyperactivity disorder (ADHD). In this review, we address three topics: (1) the cross-sectional relationship between ADHD and insomnia in adulthood, (2) the longitudinal relationship between ADHD and insomnia, and (3) insomnia as a side effect of pharmacological treatments for adult ADHD.

RECENT FINDINGS

Three cross-sectional, clinical, and population studies report a prevalence of insomnia in ADHD adults ranging from 43 to 80%. Longitudinal evidence for a link between childhood-onset ADHD and insomnia at later age is mixed, with one study confirming and another study not supporting such a longitudinal association. In randomized, placebo-controlled trials, insomnia is reported significantly more often in the treatment arm than in the placebo arm. In varying percentages of trial participants, insomnia is a treatment-emergent adverse effect in triple-bead mixed amphetamine salts (40-45%), dasotraline (35-45%), lisdexamfetamine (10-19%), and extended-release methylphenidate (11%). Ten to seventeen percent of subjects in placebo-controlled trials of atomoxetine report insomnia, possibly related to poor metabolizer status. The mechanisms explaining the relationship between ADHD and sleep problems are incompletely understood, but both genetic and non-shared environmental influences may be involved. Adults with ADHD should be assessed for insomnia, which is frequently comorbid, and both conditions should be treated.

Diagnosis and treatment of attention deficit hyperactivity disorder

Attention-deficit hyperactivity disorder (ADHD) is a neurobehavioral disorder characterized by signs and symptoms of inattention, hyperactivity, and impulsivity that typically begin in childhood. ADHD can persist into adulthood, causing impairments in occupational performance and peer and family relationships. This article reviews the epidemiology, diagnosis, and treatment of ADHD.

Organisation of services for managing ADHD

There is considerable variation in practice, both between and with different countries in the management of attention deficit hyperactivity disorder (ADHD). Whilst there is no one optimal model of service organisation there are general principles of care that can be introduced to reduce this variability. There are frequent debates and discussions about which professional group is best placed to manage ADHD at different points in the life cycle. Who delivers care is however less important than ensuring that training schemes provide adequate exposure, training and experience to both the core and non-core skills required to provide a comprehensive package of care. Most evidence-based guidelines recommend a multi-modal, multi-professional and multi-agency approach. Many also promote the use of both stepped care and shared care approaches for the management of ADHD. As most of those with ADHD continue to have ADHD-related problems into adulthood, it is important to consider how best to transition care into adulthood and think about who should deliver care to adults with ADHD. Young people with ADHD should generally be transferred to adult mental health services if they continue to have significant symptoms of ADHD or other coexisting conditions that require treatment. Unfortunately services for adults with ADHD remain relatively scarce across much of the world and some adult psychiatrists remain unsure of the diagnosis and uncertain about the appropriate use of ADHD medications in adults, but there is a strong case for increased services for adults. ADHD is on the one hand easy to treat; it is much more difficult to treat well. Although optimised care for ADHD requires routine measurement of outcomes, this often does not happen in routine clinical practice. Focusing on optimising symptoms and minimising adverse effects can significantly improve both short- and long-term outcomes.

ADHD and maturation of brain white matter: A DTI study in medication naive children and adults

Several diffusion tensor imaging (DTI) studies in attention deficit hyperactivity disorder (ADHD) have shown a delay in brain white matter (WM) development. Because these studies were mainly conducted in children and adolescents, these WM abnormalities have been assumed, but not proven to progress into adulthood. To provide further insight in the natural history of WM maturation delay in ADHD, we here investigated the modulating effect of age on WM in children and adults. 120 stimulant-treatment naive male ADHD children (10-12 years of age) and adults (23-40 years of age) with ADHD (according to DSM-IV; all subtypes) were included, along with 23 age and gender matched controls. Fractional anisotropy (FA) values were compared throughout the WM by means of tract-based spatial statistics (TBSS) and in specific regions of interest (ROIs). On both TBSS and ROI analyses, we found that stimulant-treatment naive ADHD children did not differ in FA values from control children, whereas adult ADHD subjects had reduced FA values when compared to adult controls in several regions. Significant age × group interactions for whole brain FA (p = 0.015), as well as the anterior thalamic radiation (p = 0.015) suggest that ADHD affects the brain WM age-dependently. In contrast to prior studies conducted in medicated ADHD children, we did not find WM alterations in stimulant treatment naïve children, only treatment-naïve adults. Thus, our findings suggest that the reported developmental delay in WM might appear after childhood, and that previously reported differences between ADHD children and normal developing peers could have been attributed to prior ADHD medications, and/or other factors that affect WM development, such as age and gender.

Brain imaging genetics in ADHD and beyond - Mapping pathways from gene to disorder at different levels of complexity

Attention-deficit/hyperactivity disorder (ADHD) is a common and often persistent neurodevelopmental disorder. Beyond gene-finding, neurobiological parameters, such as brain structure, connectivity, and function, have been used to link genetic variation to ADHD symptomatology. We performed a systematic review of brain imaging genetics studies involving 62 ADHD candidate genes in childhood and adult ADHD cohorts. Fifty-one eligible research articles described studies of 13 ADHD candidate genes. Almost exclusively, single genetic variants were studied, mostly focussing on dopamine-related genes. While promising results have been reported, imaging genetics studies are thus far hampered by methodological differences in study design and analysis methodology, as well as limited sample sizes. Beyond reviewing imaging genetics studies, we also discuss the need for complementary approaches at multiple levels of biological complexity and emphasize the importance of combining and integrating findings across levels for a better understanding of biological pathways from gene to disease. These may include multi-modal imaging genetics studies, bioinformatic analyses, and functional analyses of cell and animal models.

Association between childhood and adult attention deficit hyperactivity disorder symptoms in Korean young adults with Internet addiction

Background and aims Attention deficit hyperactivity disorder (ADHD) is one of the most common psychiatric comorbidities of Internet addiction (IA); however, the possible mechanisms that contribute to this high comorbidity are still under debate. This study aims to analyze these possible mechanisms by comparing the effect of IA severity and childhood ADHD on inattention, hyperactivity, and impulsivity in young adults with IA. We hypothesized that IA might have associations with ADHD-like cognitive and behavior symptoms aside from childhood ADHD. Methods Study participants consisted of 61 young male adults. Participants were administered a structured interview. The severity of IA, childhood and current ADHD symptoms, and psychiatry comorbid symptoms were assessed through self-rating scales. The associations between the severity of IA and ADHD symptoms were examined through hierarchical regression analyses. Results Hierarchical regression analyses showed that the severity of IA significantly predicted most dimensions of ADHD symptoms. By contrast, childhood ADHD predicted only one dimension. Discussion The high comorbidity of inattention and hyperactivity symptoms in IA should not solely be accounted by an independent ADHD disorder but should consider the possibility of cognitive symptoms related to IA. Functional and structural brain abnormalities associated with excessive and pathologic Internet usage might be related to these ADHD-like symptoms. Conclusion Inattention and hyperactivity in young adults with IA are more significantly associated with the severity of IA than that of childhood ADHD.

Defining the Neural Substrate of the Adult Outcome of Childhood ADHD: A Multimodal Neuroimaging Study of Response Inhibition

OBJECTIVE

Understanding the neural processes tied to the adult outcome of childhood attention deficit hyperactivity disorder (ADHD) could guide novel interventions to improve its clinical course. It has been argued that normalization of prefrontal cortical activity drives remission from ADHD, while anomalies in subcortical processes are "fixed," present even in remission. Using multimodal neuroimaging of inhibitory processes, the authors tested these hypotheses in adults followed since childhood, contrasting remitted against persistent ADHD.

METHOD

Adult participants (persistent ADHD, N=35; remit-ted ADHD, N=47; never affected, N=99) were scanned with functional MRI (fMRI) (N=85), magnetoencephalography (N=33), or both (N=63) during a response inhibition task.

RESULTS

In fMRI analyses, during inhibition, right caudate anomalies reflected a childhood ADHD history and were present even among those who remitted. By contrast, differences related to adult outcome emerged in cortical (right inferior frontal and inferior parietal/precuneus) and cerebellar regions. The persistent ADHD group showed under-activation, whereas the remitted ADHD group did not differ significantly from the never-affected group. Magnetoencephalography showed that the association between adult symptom severity and prefrontal neuronal activity was confined to the time window covering the act of inhibition (300 ms-350 ms). Group differences in cerebellar and parietal neuronal activity occurred during the time window of performance monitoring processes (500 ms-600 ms).

CONCLUSIONS

By combining fMRI and magnetoencephalography, the location and time window of neuronal activity that underpins the adult outcome of ADHD was pinpointed. Thus, the cortico-cerebellar processes tied to the clinical course of ADHD are separated from the subcortical processes that are not.

Adult ADHD and comorbid disorders: clinical implications of a dimensional approach

Attention-deficit/hyperactivity disorder (ADHD) in the adult population is frequently associated with comorbid psychiatric diseases that complicate its recognition, diagnosis and management.The prevalence of ADHD in the general adult population is 2.5% and it is associated with substantial personal and individual burden. The most frequent comorbid psychopathologies include mood and anxiety disorders, substance use disorders, and personality disorders. There are strong familial links and neurobiological similarities between ADHD and the various associated psychiatric comorbidities. The overlapping symptoms between ADHD and comorbid psychopathologies represent challenges for diagnosis and treatment. Guidelines recommend that when ADHD coexists with other psychopathologies in adults, the most impairing condition should generally be treated first.Early recognition and treatment of ADHD and its comorbidities has the potential to change the trajectory of psychiatric morbidity later in life. The use of validated assessment scales and high-yield clinical questions can help identify adults with ADHD who could potentially benefit from evidence-based management strategies.

Trajectories of attention-deficit/hyperactivity disorder dimensions in adults

OBJECTIVE

There is a lack of available information on the trajectories of attention-deficit/hyperactivity disorder (ADHD) dimensions during adulthood. This study investigates the course and the predictors of change for each ADHD domain in a clinical sample of adults with ADHD.

METHOD

Adults with ADHD (n = 344) were followed up for 7 years, with a final retention rate of 66.0%. Trajectories of inattention, hyperactivity, and impulsivity and their potential predictors were examined.

RESULTS

On average, symptoms declined in all ADHD domains during follow-up. Despite this, rises in inattentive, hyperactive, and impulsive symptoms were observed in approximately 13%, 25%, and 17% of patients respectively. Different predictors influenced the trajectory of each ADHD dimension. Oppositional defiant disorder and social phobia were associated with the maintenance of symptoms, while alcohol use disorder was associated with both maintenance and rise of symptoms.

CONCLUSION

Unexpectedly, a rise in the symptoms after 7 years was not uncommon in adults with ADHD. Prevalent comorbidities have the potential to influence the neurodevelopment and the trajectory of ADHD. Therefore, such predictors should be investigated in population cohorts to better characterize the course of ADHD. Additionally, these findings may be relevant in prevention studies and in strategies for ADHD treatment.

Subjective Distress Associated with Adult ADHD: evaluation of a new self-report

The current study aims at documenting the psychometric properties of the Subjective Distress Associated with Adult ADHD-Self-Report (SDAAA-SR), a newly developed instrument for the assessment of psychological suffering in ADHD adults. The SDAAA-SR was administered to 247 students and 142 ADHD adults. Factor structure, internal consistency, test-retest reliability, convergent validity and discriminant validity were assessed. Sensitivity to change was examined in a subsample of 25 ADHD patients who participated in a 1-year therapy. The initial pool of 62 items was reduced to 33 items distributed in a three-component structure. Internal consistency was excellent for the "distress due to inattention/disorganization" subscale and good for the "distress due to hyperactivity/impulsivity" and "distress due to self-esteem deficit" subscales. Test-retest reliability in a subsample of 98 students was substantial for all three subscales. ADHD patients scored significantly higher than students on distress due to "inattention/disorganization" and "hyperactivity/impulsivity," but no difference was observed for "self-esteem deficit." The components "inattention/disorganization" and "hyperactivity/impulsivity" displayed moderate to large correlations with the corresponding dimensions of the Adult Self-Report Scale for ADHD (ASRS-V1.1). Distress due to "inattention/disorganization" and "self-esteem deficit" was significantly associated with lower satisfaction with social behaviors (QFS, social functioning questionnaire) and quality of life (WHOQOL-BREF). Distress due to "inattention/disorganization" and "self-esteem deficit" significantly decreased after a 1-year therapy. The SDAAA-SR represents a reliable and valid measure of adult ADHD-associated distress, an important but often undocumented parameter in the clinical setting. Its use as an outcome variable in psychological interventions deserves further investigation.

Age-dependent, lasting effects of methylphenidate on the GABAergic system of ADHD patients

Stimulants are the main pharmacological treatment for patients with attention-deficit/hyperactivity disorder (ADHD). Their current prescription rates are rising, both in children, adolescents and adults. Related to the impulse control phenotype, both preclinical and clinical studies have demonstrated lower γ-amino butyric acid (GABA) levels in prefrontal brain regions in ADHD. Whereas stimulant treatment increases GABA levels, preclinical studies have suggested that stimulant treatment effects may be age-dependent. As the long-term consequences of stimulant use in ADHD children and adolescents have so far been poorly studied, we used magnetic resonance spectroscopy to assess GABA+ and glutamate + glutamine (Glx) levels in the medial prefrontal cortex (mPFC) of adult ADHD patients, both before and after an oral methylphenidate (MPH) challenge. Three groups were studied: 1) ADHD patients who were first treated with stimulants before 16 years of age, i.e. during periods of ongoing brain development (early-stimulant-treated, EST); 2) patients first treated with stimulants in adulthood (i.e. > 23 years) (late-stimulant-treated, LST), and 3) stimulant-treatment-naive (STN) ADHD patients. Reduced basal GABA+ levels were found in EST compared to LST patients (p = 0.04), while after an MPH challenge, only the EST patients showed significant increases in GABA+ (p = 0.01). For Glx, no differences were found at baseline, nor after an MPH challenge. First stimulant exposure at a young age is thus associated with lower baseline levels of GABA+ and increased responsivity in adulthood. This effect could not be found in patients that started treatment at an adult age. Hence, while adult stimulant treatment seems to exert no major effects on GABA+ levels in the mPFC, MPH may induce long-lasting alterations in the adult mPFC GABAergic system when treatment was started at a young age.

Neurodevelopmental disorders

Neurodevelopmental disorders such as attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder, although most commonly considered in childhood, can be lifelong conditions. In this Personal View that is shaped by clinical experience and research, we adopt a conceptual approach. First, we discuss what disorders are neurodevelopmental and why such a grouping is useful. We conclude that both distinction and grouping are helpful and that it is important to take into account the strong overlap across neurodevelopmental disorders. Then we highlight some challenges in bridging research and clinical practice. We discuss the complexity of clinical phenotypes and the importance of the social context. We also argue the importance of viewing neurodevelopmental disorders as traits but highlight that this is not the only approach to use. Finally, we consider developmental change across the life-span. Overall, we argue strongly for a flexible approach in clinical practice that takes into consideration the high level of heterogeneity and overlap in neurodevelopmental disorders and for research to link more closely to what is observed in real-life practice.

Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is a common, early-onset, persistent developmental disorder of childhood and adolescence, with a prevalence of approximately 5%.

METHODS

This article is based on publications retrieved by a selective search in PubMed with an emphasis on pertinent guidelines and systematic reviews.

RESULTS

At least 75% of affected children and adolescents develop a comorbid disorder, which impedes diagnosis and treatment and worsens prognosis. The etiology of ADHD is complex and heterogeneous, involving a major genetic component and diverse neurobiological alterations. Prenatal environmental factors also seem to elevate the risk of ADHD. The mainstays of treatment are psychoeducation, behavioral therapy, and psychoactive drugs, which generally have only mild side effects, such as insomnia or decreased appetite. The indication for treatment in the individual case is based on severity, comorbidity, previous therapy attempts, and the familial, social, and educational framework conditions.

CONCLUSION

Translational research is needed to clarify the etiology of ADHD. Epidemiological studies published since 1987 do not reveal any increase in the prevalence of ADHD among children and adolescents. Improved diagnosis necessitates an evidence-based and need-adapted approach to treatment.

Reward-related ventral striatum activity links polygenic risk for attention-deficit/hyperactivity disorder to problematic alcohol use in young adulthood

BACKGROUND

Problematic alcohol use in adolescence and adulthood is a common and often debilitating correlate of childhood attention-deficit/hyperactivity disorder (ADHD). Converging evidence suggests that ADHD and problematic alcohol use share a common additive genetic basis, which may be mechanistically related to reward-related brain function. In the current study, we examined whether polygenic risk for childhood ADHD is linked to problematic alcohol use in young adulthood through alterations in reward-related activity of the ventral striatum, a neural hub supporting appetitive behaviors and reinforcement learning.

METHODS

Genomic, neuroimaging, and self-report data were available for 404 non-Hispanic European-American participants who completed the ongoing Duke Neurogenetics Study. Polygenic risk scores for childhood ADHD were calculated based on a genome-wide association study meta-analysis conducted by the Psychiatric Genomics Consortium and tested for association with reward-related ventral striatum activity, measured using a number-guessing functional magnetic resonance imaging paradigm, and self-reported problematic alcohol use. A mediational model tested whether ventral striatum activity indirectly links polygenic risk for ADHD to problematic alcohol use.

RESULTS

Despite having no main effect on problematic alcohol use, polygenic risk for childhood ADHD was indirectly associated with problematic alcohol use through increased reward-related ventral striatum activity.

CONCLUSIONS

Individual differences in reward-related brain function may, at least in part, mechanistically link polygenic risk for childhood ADHD to problematic alcohol use.

Familial aggregation of attention-deficit/hyperactivity disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) aggregates in families. To date, the strength, pattern, and characteristics of the familial aggregation have not been thoroughly assessed in a population-based family sample.

METHODS

In this cohort study, we identified relative pairs of twins, full and half-siblings, and full and half cousins from 1,656,943 unique individuals born in Sweden between 1985 and 2006. The relatives of index persons were followed from their third birthday to 31 December 2009 for ADHD diagnosis. Birth year adjusted hazard ratio (HR), that is, the rate of ADHD in relatives of ADHD-affected index persons compared with the rate of ADHD in relatives of unaffected index persons, was estimated in the different types of relatives using Cox proportional hazards model.

RESULTS

During the follow-up, 31,865 individuals were diagnosed with ADHD (male to female ratio was 3.7). The birth year adjusted HRs were as follows: 70.45 for monozygotic twins; 8.44 for dizygotic twins; 8.27 for full siblings; 2.86 for maternal half-siblings; 2.31 for paternal half-siblings; 2.24 for full cousins; 1.47 for half cousins. Maternal half-siblings had significantly higher HR than in paternal half-siblings. The HR did not seem to be affected by index person's sex. Full siblings of index persons with ADHD diagnosis present at age 18 or older had a higher rate of ADHD (HR: 11.49) than full siblings of index persons with ADHD diagnosis only before age 18 (HR: 4.68).

CONCLUSIONS

Familial aggregation of ADHD increases with increasing genetic relatedness. The familial aggregation is driven by not only genetic factors but also a small amount of shared environmental factors. Persistence of ADHD into adulthood indexes stronger familial aggregation of ADHD.