Inferring candidate genes for attention deficit hyperactivity disorder (ADHD) assessed by the World Health Organization Adult ADHD Self-Report Scale (ASRS)

Temporal Structure in Sensorimotor Variability: A Stable Trait, But What For?

Human performance shows substantial endogenous variability over time, and this variability is a robust marker of individual differences. Of growing interest to psychologists is the realisation that variability is not fully random, but often exhibits temporal dependencies. However, their measurement and interpretation come with several controversies. Furthermore, their potential benefit for studying individual differences in healthy and clinical populations remains unclear. Here, we gather new and archival datasets featuring 11 sensorimotor and cognitive tasks across 526 participants, to examine individual differences in temporal structures. We first investigate intra-individual repeatability of the most common measures of temporal structures - to test their potential for capturing stable individual differences. Secondly, we examine inter-individual differences in these measures using: (1) task performance assessed from the same data, (2) meta-cognitive ratings of on-taskness from thought probes occasionally presented throughout the task, and (3) self-assessed attention-deficit related traits. Across all datasets, autocorrelation at lag 1 and Power Spectra Density slope showed high intra-individual repeatability across sessions and correlated with task performance. The Detrended Fluctuation Analysis slope showed the same pattern, but less reliably. The long-term component (d) of the ARFIMA(1,d,1) model showed poor repeatability and no correlation to performance. Overall, these measures failed to show external validity when correlated with either mean subjective attentional state or self-assessed traits between participants. Thus, some measures of serial dependencies may be stable individual traits, but their usefulness in capturing individual differences in other constructs typically associated with variability in performance seems limited. We conclude with comprehensive recommendations for researchers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42113-022-00162-1.

Attention deficit hyperactivity symptoms predict problematic mobile phone use

Attention-deficit-hyperactivity disorder (ADHD) is the most commonly diagnosed childhood disorder characterised by inattention, hyperactivity/impulsivity, or both. Some of the key traits of ADHD have previously been linked to addictive and problematic behaviours. The aim of the present study was to examine the relationship between problematic mobile phone use, smartphone addiction risk and ADHD symptoms in an adult population. A sample of 273 healthy adult volunteers completed the Adult ADHD Self-Report Scale (ASRS), the Mobile Phone Problem Usage Scale (MPPUS), and the Smartphone Addiction Scale (SAS). A significant positive correlation was found between the ASRS and both scales. More specifically, inattention symptoms and age predicted smartphone addiction risk and problematic mobile phone use. Our results suggest that there is a positive relationship between ADHD traits and problematic mobile phone use. In particular, younger adults with higher level of inattention symptoms could be at higher risk of developing smartphone addiction. The implication of our findings for theoretical frameworks of problematic mobile phone use and clinical practice are discussed.

Depressive mood changes are associated with self-perceptions of ADHD characteristics in adults

Subjective attention deficit/hyperactivity disorder (ADHD) symptoms seen in adult depressive patients have often become a pathophysiological topic in recent years. Screening questionnaires are widely used for detecting ADHD; however, the risk of misdiagnosis exists. The present study examined whether self-perceptions of ADHD-related characteristics were consistent regardless of changes in the severity of depressive symptoms. Between April to October 2018, newly diagnosed depressed outpatients aged 24-59 years with good social functioning and without a history of ADHD were asked to fill out the Adult ADHD Self-Report Scale version 1.1 (ASRS) and the Beck Depression Inventory (BDI) at baseline (n = 726) and 12-week follow-up (n = 202). A statistically significant correlation was found between a change in BDI and ASRS scores (score at baseline minus score at the endpoint; r = .57). In addition, the higher the rate of improvement in BDI, the lower the frequency of positive screening for ADHD by ASRS. This study showed that subjective ADHD symptoms were correlated with depressive states. Diagnostic evaluation of comorbid ADHD using self-report scales in a primary care setting should be made with caution.

The Emotional Dysregulation Questionnaire: Development and comparative analysis

OBJECTIVES

A widely used measure of emotion dysregulation, the Difficulties in Emotion Regulation Scale (DERS), may insufficiently cover a number of potentially important aspects of emotional dysregulation. A new measure of emotional dysregulation, the Emotional Dysregulation Questionnaire (EDQ) was therefore developed based upon an eight-factor model of the construct.

DESIGN AND METHOD

The DERS and the EDQ were administered to a community sample (N = 362; 183 female, 179 male), along with a number of measures of psychopathology associated with emotional dysregulation. The capacity of the EDQ and the DERS to account for the emotional dysregulation associated with these different types of psychopathology was then compared.

RESULTS

In several of the psychopathologies examined, the EDQ could account for more variation than the DERS, suggesting that it more comprehensively assessed the emotion regulation deficits associated with these issues.

CONCLUSIONS

Results suggest the EDQ possesses several advantages relative to the DERS, allowing for a more comprehensive and accurate assessment of emotional dysregulation.

PRACTITIONER POINTS

Emotional dysregulation is a common component of many psychological disorders. The Difficulties in Emotion Regulation Scale is one of the primary self-report measures used to asses these difficulties, however, concerns exist that it may not comprehensively assess the construct of emotional dysregulation. A new self-report measure of comparable length, the Emotional Dysregulation Questionnaire has been developed, with this new measure possessing several advantages relative to the DERS with regard to the assessment of emotional dysregulation. The use of this measure in clinical practice may more accurately identify the emotion regulation deficits present in clients.

Age and Gender Measurement Noninvariance of the Adult ADHD Self-Report Scale Screener

Objective: The nature and form of demographics-related differences in ADHD self-reported symptoms across adulthood is currently poorly understood. This study explored the psychometrics of the Adult ADHD Self-Report Scale Screener (ASRS-6), including its age- and gender-related measurement invariance. Method: Structural equation models were used to analyze adult data-aged 16 to 95 years-from the 2007 British Adult Psychiatric Morbidity Survey. Results: The three-factor model (disorganization, inattention, hyperactivity) outperformed one- and two-factor models. Self-reported attentional deficits may be more pathognomonic of overall self-reported ADHD in adults than other symptoms. All items exhibited age measurement noninvariance while only a subset exhibited gender measurement noninvariance. Individuals who are male and younger tend to have lower thresholds for endorsement for ASRS-6 items than individuals who are female and older. Conclusion: The ASRS-6 does not appear to be unidimensional, and self-reported ASRS-6 symptomatology changes in meaning with age.

The relationship between sensory processing sensitivity and attention deficit hyperactivity disorder traits: A spectrum approach

The aim of the present study was to examine the relationship between sensory processing sensitivity (SPS) and symptoms of Attention Deficit Hyperactivity Disorder (ADHD) in adults. The Highly Sensitive Person Scale (HSPS) scale and the Adult ADHD Self-Report Scale (ASRS) were administered to a non-clinical group of 274 participants recruited from a university volunteers list. We found a highly significant positive correlation between number of self-reported ADHD traits and sensory sensitivity. Furthermore, ADHD traits and age were predictors of SPS and exploratory factor analysis revealed a factor that combined ADHD traits and items from the HSPS. The psychometric properties of the HSPS were also examined supporting the unidimensional nature of the concept. To our knowledge, this is the first study to identify a positive relationship between HSPS and ADHD traits in the general population. Our results further support recent findings suggesting abnormal sensory processing in ADHD.

[The combined effect of genetic factors and attention deficit hyperactivity disorder on the development of dependence on synthetic cannabinoids]

AIM

To develop a model of assessment of individual risk of dependence on synthetic cannabinoids based on genetic factors and diagnosis of attention deficit hyperactivity disorder (ADHD).

MATERIAL AND METHODS

The study included 146 male adolescents using synthetic cannabinoids and 136 healthy people. The genetic study considered the combination of dependence on synthetic cannabinoids and ADHD. Six polymorphisms in the genes of dopaminergic and serotonergic systems were genotyped.

RESULTS AND CONCLUSION

In general, the results of this work confirm the important role of the dopaminergic and serotonergic systems in the pathogenesis of substance use disorders, and the significance of changes in the nucleotide sequences of DRD2, SLC6A3, HTR2A genes in the development of dependence on synthetic cannabinoids with ADHD.

German validation of the Conners Adult ADHD Rating Scales (CAARS) II: Reliability, validity, diagnostic sensitivity and specificity

Background

The German version of the Conners Adult ADHD Rating Scales (CAARS) has proven to show very high model fit in confirmative factor analyses with the established factors inattention/memory problems, hyperactivity/restlessness, impulsivity/emotional lability, and problems with self-concept in both large healthy control and ADHD patient samples. This study now presents data on the psychometric properties of the German CAARS-self-report (CAARS-S) and observer-report (CAARS-O) questionnaires.

Methods

CAARS-S/O and questions on sociodemographic variables were filled out by 466 patients with ADHD, 847 healthy control subjects that already participated in two prior studies, and a total of 896 observer data sets were available. Cronbach's-alpha was calculated to obtain internal reliability coefficients. Pearson correlations were performed to assess test-retest reliability, and concurrent, criterion, and discriminant validity. Receiver Operating Characteristics (ROC-analyses) were used to establish sensitivity and specificity for all subscales.

Results

Coefficient alphas ranged from .74 to .95, and test-retest reliability from .85 to .92 for the CAARS-S, and from .65 to .85 for the CAARS-O. All CAARS subscales, except problems with self-concept correlated significantly with the Barrett Impulsiveness Scale (BIS), but not with the Wender Utah Rating Scale (WURS). Criterion validity was established with ADHD subtype and diagnosis based on DSM-IV criteria. Sensitivity and specificity were high for all four subscales.

Conclusion

The reported results confirm our previous study and show that the German CAARS-S/O do indeed represent a reliable and cross-culturally valid measure of current ADHD symptoms in adults.

Association between tendencies for attention-deficit/hyperactivity disorder (ADHD) and the 2D:4D digit ratio: a cross-cultural replication in Germany and China

Prenatal testosterone is considered to be a possible factor contributing to the development of attention-deficit/hyperactivity disorder (ADHD) symptomatology, but findings regarding the connection between individual variations in prenatal testosterone exposure as (indirectly) indexed by the second-to-fourth digit (2D:4D) ratio and ADHD remain inconsistent. To clarify the inconsistent findings and to facilitate generalization on the association between subclinical variations in ADHD tendencies and lower 2D:4D ratios the current study applied a cross-cultural replication approach employing independent healthy adult cohorts from Germany and China. Samples from Germany and China were matched for gender and age (in each sample n_males = 96, n_females = 96; age_Germany: M = 21.47, SD = 2.55; age_China: M = 21.36, SD = 2.28). All participants filled in the Adult ADHD Self-Report Scale Symptom Checklist (ASRS) and provided hand scans to measure 2D:4D ratios. The German sample had significantly higher 2D:4D ratios than the Chinese sample but in both samples males had significantly lower 2D:4D ratios than females. The hypothesised negative association between 2D:4D ratios and ADHD tendencies was observed on a descriptive level in German and Chinese males and with one exception in Chinese females. But only in German males correlations gained significance (range: r = -0.198 to r = -0.177). The observed effect sizes are in line with former research that was conducted in samples from different cultures. In future research on the connection between testosterone and ADHD not only prenatal but also postnatal testosterone as well as possible moderators like childhood maltreatment should be taken into account.

Reliability and correlates of intraindividual variability in the oculomotor system

Even if all external circumstances are kept equal, the oculomotor system shows intraindividual variability over time, affecting measures such as microsaccade rate, blink rate, pupil size, and gaze position. Recently, some of these measures have been associated with ADHD on a between-subject level. However, it remains unclear to what extent these measures constitute stable individual traits. In the current study, we investigate the intraindividual reliability of these oculomotor features. Combining results over three experiments (> 100 healthy participants), we find that most measures show good intra-individual reliability over different time points (repeatability) as well as over different conditions (generalisation). However, we find evidence against any correlation with self-assessed ADHD tendencies, mind wandering, and impulsivity. As such, the oculomotor system shows reliable intra-individual reliability, but its benefit for investigating self-assessed individual differences in healthy subjects remains unclear. With our results, we highlight the importance of reliability and statistical power when studying between-subject differences.

Co-Occurrence of ASD and ADHD Traits in an Adult Population

Objective: ADHD and autism spectrum disorder (ASD) can be viewed as the extreme end of traits found in the general population. Clinical and genetic studies suggest that ADHD and ASD often co-occur and share genetic susceptibility. The aim of this study was to examine co-occurrence of ADHD and ASD traits in the general population. Method: In total, 334 participants were recruited from a population-based sample. Four questionnaires assessing current and retrospective ADHD and ASD traits were administered online: the Adult ADHD Self-Report Scale (ASRS) Symptom Checklist, the Wender Utah Rating Scale (WURS-25), the Broad Autism Phenotype Questionnaire (BAPQ), and the Autism Spectrum Quotient (AQ). Results: A significant correlation was found between ADHD and autistic traits. In particular, higher inattention and overall ADHD scores were associated with self-reported deficits in communication and social skills. Conclusion: Our findings are similar to results from studies on clinical populations, suggesting that ADHD and ASD might share common etiology.

Evaluation of Risk Factors for ADHD and Co-Morbid Psychiatric Disorders Among the Parents of Children With ADHD

OBJECTIVE

The aim of this study is to investigate the presence of ADHD and other psychiatric disorders among parents with at least one child with ADHD relative to parents with children who do not have ADHD.

METHOD

Eighty five parents of children with ADHD with 68 control parents who had healthy children without ADHD were interviewed for participation in present study. Each parent was evaluated for co-existing psychiatric disorders using the Structured Clinical Interview for the DSM IV Axis I Disorders (SCID I).

RESULTS

We found that ADHD and co-morbid psychiatric symptoms were increased in the parents of children with ADHD in comparison with the healthy control group.

CONCLUSION

Psychiatric co-morbidity was more common among the parents of patients with inattentive and combined presentations. Adult ADHD is associated with psychiatric co-morbidities including anxiety disorders, mood disorders, and somatoform disorders as well as substantial role impairment.

The relationship between internet addiction, attention deficit hyperactivity symptoms and online activities in adults

AIM

The objective of this study was to examine the relationship between Internet Addiction (IA), Attention Deficit Hyperactivity Disorder (ADHD) symptoms and online activities in an adult population.

METHODS

A sample of 400 individuals aged 18 to 70 completed the Adult ADHD Self-Report Scale (ASRS), Young's Internet Addiction Test, and their preferred online activities.

RESULTS

A moderate association was found between higher levels of ADHD symptoms and IA. The best predictors of IA scores were ADHD symptoms, age, playing online games and spending more time online.

CONCLUSION

Our findings further support a positive relationship between ADHD symptoms and excessive internet use.

Interaction Between Season of Birth and COMT Val158Met (rs4680) in ADHD in a Large Sample of Chinese Han Participants

OBJECTIVE

To investigate the interaction between catechol-O-methyltransferase gene (COMT) Val108/158Met (rs4680) and season of birth (SOB) on ADHD and its symptoms.

METHOD

We conducted transmission disequilibrium tests (TDTs) in 976 trios, then further performed the above analyses in subgroups according to SOB. Quantitative analyses were performed for ADHD symptoms evaluated by ADHD Rating Scale-IV in 1,530 ADHD cases.

RESULTS

Overall, there was no association between COMT and ADHD. After stratification, we found an increased transmission of the Val allele in the trios born in spring, while a decreased transmission was observed in the autumn months. We also observed a significant interaction between Val108/158Met and SOB on ADHD symptoms. Among those born in spring, Met carriers had milder ADHD symptoms compared with Val homozygotes, whereas opposite association was found in those born in autumn.

CONCLUSION

Our study provided evidence for the modifying effect of SOB on the association between COMT and ADHD along with its symptoms.

Problematic Video Game Play and ADHD Traits in an Adult Population

This study examined the relationship between problematic video game play (PVGP), video game usage, and attention deficit hyperactivity disorder (ADHD) traits in an adult population. A sample of 205 healthy adult volunteers completed the Adult ADHD Self-Report Scale (ASRS), a video game usage questionnaire, and the Problem Video Game Playing Test (PVGT). A significant positive correlation was found between the ASRS and the PVGT. More specifically, inattention symptoms and time spent playing video games were the best predictors of PVGP. No relationship was found between frequency and duration of play and ADHD traits. Hyperactivity symptoms were not associated with PVGP. Our results suggest that there is a positive relationship between ADHD traits and problematic video game play. In particular, adults with higher level of self-reported inattention symptoms could be at higher risk of PVGP.

The relationship between ADHD traits and sensory sensitivity in the general population

Preliminary studies in children and adults with Attention Deficit Hyperactivity Disorder (ADHD) report both hypo-responsiveness and hyper-responsiveness to sensory stimuli, as well as problems modulating sensory input. As it has been suggested that those with ADHD exist at the extreme end of a continuum of ADHD traits, which are also evident in the general population, we investigated the link between ADHD and sensory sensitivity in the general population. Two online questionnaires measuring ADHD traits and sensory responsivity across various sensory domains were administered to 234 participants. Results showed a highly significant positive correlation between the number of ADHD traits and the frequency of reported sensory processing problems. An increased number of sensory difficulties across all modalities were associated with the level of ADHD. Furthermore, ADHD traits predicted sensory difficulties and exploratory factor analysis revealed a factor that combined ADHD trait and sensory processing items. This is the first study to identify a positive relationship between sensory processing and ADHD traits in the general population. Our results suggest that sensory difficulties could be part of the ADHD phenotype.

Multisensory integration and ADHD-like traits: Evidence for an abnormal temporal integration window in ADHD

Abnormalities in multimodal processing have been found in many developmental disorders such as autism and dyslexia. However, surprisingly little empirical work has been conducted to test the integrity of multisensory integration in Attention Deficit Hyperactivity Disorder (ADHD). The main aim of the present study was to examine links between symptoms of ADHD (as measured using a self-report scale in a healthy adult population) and the temporal aspects of multisensory processing. More specifically, a Simultaneity Judgement (SJ) and a Temporal Order Judgement (TOJ) task were used in participants with low and high levels of ADHD-like traits to measure the temporal integration window and Just-Noticeable Difference (JND) (respectively) between the timing of an auditory beep and a visual pattern presented over a broad range of stimulus onset asynchronies. The Point of Subjective Similarity (PSS) was also measured in both cases. In the SJ task, participants with high levels of ADHD-like traits considered significantly fewer stimuli to be simultaneous than participants with high levels of ADHD-like traits, and the former were found to have significantly smaller temporal windows of integration (although no difference was found in the PSS in the SJ or TOJ tasks, or the JND in the latter). This is the first study to identify an abnormal temporal integration window in individuals with ADHD-like traits. Perceived temporal misalignment of two or more modalities can lead to distractibility (e.g., when the stimulus components from different modalities occur separated by too large of a temporal gap). Hence, an abnormality in the perception of simultaneity could lead to the increased distractibility seen in ADHD.

Attention-Deficit Hyperactivity Disorder-Like Traits and Distractibility in the Visual Periphery

We examined the performance of nonclinical subjects with high and low levels of self-reported attention-deficit hyperactivity disorder (ADHD)-like traits in a novel distractibility paradigm with far peripheral visual distractors, the likely origin of many distractors in everyday life. Subjects were tested on a Sustained Attention to Response Task with distractors appearing before some of the target or nontarget stimuli. When the distractors appeared 80 ms before the targets or nontargets, participants with high levels of ADHD-like traits were less affected in their reaction times than those with lower levels. Reducing the distractor-target or nontarget interval to 10 ms removed the reaction time advantage for the high group. We suggest that at 80 ms, the distractors were cueing the arrival of the target or nontarget, and that those with high levels of ADHD-like traits were more sensitive to the cues. Increased sensitivity to stimuli in the visual periphery is consistent with hyperresponsiveness at the level of the superior colliculus.

Child maltreatment and ADHD symptoms in a sample of young adults

OBJECTIVE

The present study investigated the relationship between different types of childhood maltreatment (emotional, sexual, overall abuse, and no abuse) and the symptoms of attention deficit hyperactivity disorder (ADHD) in young adulthood.

METHOD

Data were collected from a Danish national study conducted by The Danish National Centre for Social Research in 2008 and 2009. A sample of 4,718 young adults (24 years of age) were randomly selected using the total birth cohort of children born in 1984. Structured interviews were conducted with a response rate of 63%, equating to a total sample size of 2,980 participants.

RESULTS

Chi-square analyses revealed significant relationships between child maltreatment groups and a probable diagnosis of ADHD using the Adult ADHD Self-Report Scale (ASRS). Binary logistic regression analysis showed that the overall abuse class was more strongly associated with probable ADHD (OR=5.08), followed by emotional abuse (OR=3.09) and sexual abuse (OR=2.07).

CONCLUSIONS

The results showed that childhood maltreatment was associated with increased risk of ADHD symptoms in young adulthood. The findings of this study are discussed within the existing literature and suggestions for future research are outlined in order to replicate these findings in other adult populations.

Gently restless: association of ADHD-like traits with response inhibition and interference control

Impairment of inhibition-related functions is one of the most pronounced cognitive deficits found in attention-deficit/hyperactivity disorder (ADHD). Compelling evidence from studies of unaffected relatives of patients with ADHD and of ADHD-like traits in healthy subjects suggest the continuous distribution of ADHD symptoms in the population. A more subtle inhibitory deficit can also be found in healthy relatives of patients and in subjects with high ADHD-like traits. Here, we examined the relationship between inhibitory performance and ADHD-like traits, for the first time, in a large sample of healthy adults by applying multiple, widely used tests of inhibition-related functions. ADHD-like traits, in general, were independently predicted by Stroop interference score and, at trend level, by go/no-go commission error rate while controlling for socio-demographic factors, verbal intelligence and neuroticism. Additionally, higher inattentive traits were related to worse Stroop performance at trend level, and higher hyperactive/impulsive traits were significantly associated with more go/no-go commission errors. ADHD-like traits were strongly related to neuroticism. The study shows that individual differences in ADHD-like traits are related to variance in fundamental inhibition-related functions over and above effects of negative affect regulation, but the relationships tend to be small. The results suggest the quasi-dimensionality of ADHD and raise further questions about the relationship between genetic factors and the deficit of inhibition-related functions in the ADHD spectrum.

Dopamine receptor DRD4 gene and stressful life events in persistent attention deficit hyperactivity disorder

We performed a case-control association study in persistent ADHD considering eight candidate genes (DRD4, DAT1/SLC6A3, COMT, ADRA2A, CES1, CYP2D6, LPHN3, and OPRM1) and found additional evidence for the involvement of the Dup 120bp and VNTR 48bp functional variants within the dopamine receptor DRD4 gene in the etiology of adult ADHD. We subsequently investigated the interaction of stressful life events with these two DRD4 polymorphisms, and the impact of such events on the severity of ADHD symptomatology. The gene-by-environment analysis revealed an independent effect of stressful experiences on the severity of persistent ADHD, and a gene-by-environment interaction on the inattentive dimension of the disorder, where non carriers of the Dup 120bp (L) - VNTR 48bp (7R) haplotype were more sensitive to environmental adversity than carriers. These results are in agreement with previous works reporting a relationship between DRD4 and the effect of adverse experiences, which may explain the discordant findings in previous genetic studies and strengthen the importance of gene-by-environment interactions on the severity of ADHD. © 2015 Wiley Periodicals, Inc.

Reduced neural error signaling in left inferior prefrontal cortex in young adults with ADHD

OBJECTIVE

The neural network involved in inhibition of inappropriate response tendencies shares commonalities with the error-processing network, signaling failure of inhibition. Most studies on error processing in ADHD have been conducted in children using electrophysiological methods.

METHOD

Using event-related functional magnetic resonance imaging, the authors studied 14 adults with ADHD and 12 group-matched healthy control participants while performing a modified version of a combined Eriksen Flanker-Go/NoGo-task.

RESULTS

Patients with ADHD demonstrated significantly reduced error signaling in the left inferior frontal gyrus bordering the anterior insular cortex (BA 47), computed from the contrast of unsuccessful minus successful inhibition trials.

CONCLUSION

Hypoactivation of the left inferior frontal cortex during error signaling might represent a neurofunctional marker of a crucial prerequisite for error processing in adults with ADHD. This possibly indicates a dysfunction of the neural system that operates task-set related representations and monitoring of erroneous performances in service of ensuing posterror processing.

Parenting Behavior Mediates the Intergenerational Association of Parent and Child Offspring ADHD Symptoms

Although there are likely to be multiple mechanisms underlying parent attention-deficit/hyperactivity disorder (ADHD) symptoms as a key risk factor for offspring ADHD, potential explanatory factors have yet to be reliably identified. Given that parent ADHD symptoms independently predict parenting behavior and child ADHD symptoms, we tested whether individual differences in multiple dimensions of positive and negative parenting behavior (i.e., corporal punishment, inconsistent discipline, positive parenting behavior, observed negative talk, and observed praise) mediated the association between parental and offspring ADHD. We used a prospective design that featured predictors (i.e., parent ADHD symptoms) and mediators (i.e., parenting behavior) that temporally preceded the outcome (i.e., offspring ADHD symptoms). Using a well-characterized sample of 120 children with and without ADHD (ages 5-10 at Wave 1, 7-12 at Wave 2) and their biological parents, we examined multimethod (i.e., observed, self-report) measures of positive and negative parenting behavior as simultaneous mediators of the association of Wave 1 parent and Wave 2 offspring ADHD symptoms. Using a multiple mediation framework, consisting of rigorous bootstrapping procedures and controlling for parent depression, child's baseline ADHD and oppositional defiant disorder, and child's age, corporal punishment significantly and uniquely mediated the association of Wave 1 parent ADHD symptoms and Wave 2 offspring ADHD. We consider the role of parenting behavior in the intergenerational transmission of ADHD as well as implications of these findings for the intervention and prevention of childhood ADHD.

The association between the catechol-O-methyltransferase Val108/158Met polymorphism and hyperactive-impulsive and inattentive symptoms in youth

RATIONALE

Hyperactivity, impulsivity, and inattention are major symptoms occurring in attention-deficit/hyperactivity disorder. This disorder is highly heritable, multifactorial, polygenic, and associated primarily with dysfunctions of dopaminergic, noradrenergic, and serotonergic systems.

OBJECTIVES

The present study tested the possible association of the catechol-O-methyltransferase (COMT) Val108/158Met (rs4680) polymorphism with hyperactive-impulsive and inattentive symptoms in male youth.

METHOD

Polymorphism COMT Val108/158Met was analyzed in 807 male unrelated Caucasian young subjects: 231 healthy controls, 195 subjects with moderate hyperactive symptoms and 254 subjects with moderate inattentive symptoms, 111 subjects with severe hyperactive symptoms and 90 subjects with severe inattentive symptoms, all evaluated using Swanson, Nolan, and Pelham Questionnaire IV criteria.

RESULTS

The frequency of the COMT genotypes, alleles, and the homozygous Met/Met genotype versus Val carriers (χ²) test with standardized residuals) differed significantly between subjects without and subjects with hyperactive-impulsive and inattentive symptoms. In addition, significantly higher hyperactive-impulsive and inattentive scores were found in subjects with the Met/Met genotype compared to carriers of other COMT genotypes. These significant results were due to the more frequent occurrence of Met/Met genotype or the Met allele in subjects with moderate and severe hyperactive-impulsive and inattentive symptoms compared to matched controls.

CONCLUSION

These results suggest that the Met/Met genotype or the Met allele of the COMT Val108/158Met, contributing to higher dopaminergic activity, are significantly overrepresented in subjects with moderate or severe hyperactive-impulsive and inattentive symptoms, and that this polymorphism is significantly associated with hyperactive-impulsive and inattentive symptoms in young boys and adolescents.

Impulsivity is related to striatal dopamine transporter availability in healthy males

Impulsivity characterises various psychiatric disorders, particularly attention-deficit/hyperactivity disorder (ADHD). Evidence shows that ADHD symptoms are associated with dopamine dysfunction and alleviated with methylphenidate, a drug that reduces dopamine transporter availability. ADHD-like symptoms and impulsive traits are continuously distributed across the general population. Here, we aimed to investigate the dopaminergic basis of impulsivity and other ADHD-related traits in healthy individuals by studying the association of these traits with striatal dopamine transporter availability. Single-photon emission computed tomography with [(123)I] FP-CIT was performed on 38 healthy males. Impulsivity was measured using the Barratt Impulsiveness Scale (BIS) and hyperactivity-impulsivity and inattention using the Adult ADHD Self-Report Scale (ASRS). We found that greater dopamine transporter availability was associated with higher BIS impulsivity but not with ADHD-related traits. The association with BIS was significant after accounting for individual differences in age and neuroticism. These results suggest that individual differences in the dopamine system may be a neural correlate of trait impulsivity in healthy individuals.

The genetics of attention deficit/hyperactivity disorder in adults, a review

The adult form of attention deficit/hyperactivity disorder (aADHD) has a prevalence of up to 5% and is the most severe long-term outcome of this common neurodevelopmental disorder. Family studies in clinical samples suggest an increased familial liability for aADHD compared with childhood ADHD (cADHD), whereas twin studies based on self-rated symptoms in adult population samples show moderate heritability estimates of 30-40%. However, using multiple sources of information, the heritability of clinically diagnosed aADHD and cADHD is very similar. Results of candidate gene as well as genome-wide molecular genetic studies in aADHD samples implicate some of the same genes involved in ADHD in children, although in some cases different alleles and different genes may be responsible for adult versus childhood ADHD. Linkage studies have been successful in identifying loci for aADHD and led to the identification of LPHN3 and CDH13 as novel genes associated with ADHD across the lifespan. In addition, studies of rare genetic variants have identified probable causative mutations for aADHD. Use of endophenotypes based on neuropsychology and neuroimaging, as well as next-generation genome analysis and improved statistical and bioinformatic analysis methods hold the promise of identifying additional genetic variants involved in disease etiology. Large, international collaborations have paved the way for well-powered studies. Progress in identifying aADHD risk genes may provide us with tools for the prediction of disease progression in the clinic and better treatment, and ultimately may help to prevent persistence of ADHD into adulthood.

Linking neurogenetics and individual differences in language learning: the dopamine hypothesis

Fundamental advances in neuroscience have come from investigations into neuroplasticity and learning. These investigations often focus on identifying universal principles across different individuals of the same species. Increasingly, individual differences in learning success have also been observed, such that any seemingly universal principle might only be applicable to a certain extent within a particular learner. One potential source of this variation is individuals' genetic differences. Adult language learning provides a unique opportunity for understanding individual differences and genetic bases of neuroplasticity because of the large individual differences in learning success that have already been documented, and because of the body of empirical work connecting language learning and neurocognition. In this article, we review the literature on the genetic bases of neurocognition, especially studies examining polymorphisms of dopamine (DA)-related genes and procedural learning. This review leads us to hypothesize that there may be an association between DA-related genetic variation and language learning differences. If this hypothesis is supported by future empirical findings we suggest that it may point to neurogenetic markers that allow for language learning to be personalized.

New marker using bioimpedance technology in screening for attention deficit/hyperactivity disorder (ADHD) in children as an adjunct to conventional diagnostic methods

Background

Diagnosis of attention deficit/hyperactivity disorder (ADHD) in children is not straightforward and misdiagnosis may occur, which leads to the possibility of errors in treatment, with numerous possible side effects that could be especially damaging in view of the age of the population. For this reason, a tool that is easy to use, fast, and cost-effective, which provides an addition to conventional diagnosis and treatment monitoring of ADHD children, is needed. In this study, electro interstitial scans (EIS) were used to perform bioimpedance measurements. The results of conductivity measurements taken using forehead electrodes in a group of children conventionally diagnosed with ADHD and in a control group not showing any symptoms of ADHD were compared.

Method

Sixty children without any ADHD symptoms (group 1) and 52 children diagnosed with ADHD following psychiatric examination (group 2) underwent an examination with the EIS system. Statistical analysis was performed to compare the conductivity measurements at the level of the forehead electrodes, using independent t-tests and a receiver-operating characteristic curve (ROC) to determine the specificity and sensitivity of the test.

Results

The mean of the conductivity measurements of two pathways between the forehead electrodes (from left forehead to right forehead and from right forehead to left forehead) in the ADHD group was 33.11 micro Siemens (mS) (range 2–113 mS). This was significantly higher (P < 0.001) than mean of the conductivity measurements of two pathways between the forehead electrodes of the control group (2.75 mS, range 1.75–27.4 mS). In terms of the ROC results, comparing the two groups using the reference of the mean of conductivity measurements of the two pathways between the forehead electrodes, the test showed a specificity of 98% and sensitivity of 80% and P = 0.0001 (95% confidence interval) with a cutoff value at 7.4 mS.

Conclusion

The EIS marker related to the conductivity measurements of the forehead pathway has a high specificity and high sensitivity and use of this could provide practitioners with a noninvasive, low-cost system that is easy to use in the office and could offer an adjunct to the conventional diagnosis of ADHD children. It could also assist in treatment monitoring, and allow for earlier intervention.

Activation of Inhibition: Diminishing Impulsive Behavior by Direct Current Stimulation over the Inferior Frontal Gyrus

A common feature of human existence is the ability to reverse decisions after they are made but before they are implemented. This cognitive control process, termed response inhibition, refers to the ability to inhibit an action once initiated and has been localized to the right inferior frontal gyrus (rIFG) based on functional imaging and brain lesion studies. Transcranial direct current stimulation (tDCS) is a brain stimulation technique that can facilitate as well as impair cortical function. To explore whether response inhibition can be improved through rIFG electrical stimulation, we administered focal tDCS before subjects performed the stop signal task (SST), which measures response inhibition. Notably, activation of the rIFG by unilateral anodal stimulation significantly improved response inhibition, relative to a sham condition, whereas the same tDCS protocol did not affect response time in the go trials of the SST and in a control task. Furthermore, the SST was not affected by tDCS at a control site, the right angular gyrus. Our results are the first demonstration of response inhibition improvement with brain stimulation over rIFG and further confirm the rIFG involvement in this task. Although this study was conducted in healthy subjects, present findings with anodal rIFG stimulation support the use of similar paradigms for the treatment of cognitive control impairments in pathological conditions.

Persistent nonmedical use of prescription stimulants among college students: possible association with ADHD symptoms

OBJECTIVE

To investigate the possible association between untreated ADHD symptoms (as measured by the Adult ADHD Self-Report Scale) and persistent nonmedical use of prescription stimulants.

METHOD

Multinomial regression modeling was used to compare ADHD symptoms among three groups of college students enrolled in a longitudinal study over 4 years: (1) persistent nonmedical users of prescription stimulants, (2) persistent users of marijuana who did not use prescription stimulants nonmedically, and (3) consistent nonusers of drugs.

RESULTS

ADHD symptoms were associated with being a persistent nonmedical user of prescription stimulants after adjustment for race/ethnicity, sex, socioeconomic status, and other illicit drug use. No associations were observed between ADHD symptoms and being a persistent marijuana user or nonuser.

CONCLUSION

ADHD symptoms, and in particular inattention symptoms, appeared to be associated with nonmedical use of prescription stimulants.

Sex modulates the associations between the COMT gene and personality traits

Previous research has shown inconsistent findings regarding the relations between the functional Val158Met polymorphisms of the catechol-O-methyltransferase (COMT) gene and individual differences in personality traits. This study attempts to overcome some of the weaknesses of previous research, namely, small sample sizes, clinical samples, ethnic stratification, wide age ranges, neglecting sex differences, and single measures of personality traits. A large sample (n = 556, 250 male, 306 female) of healthy Chinese college students (mean age = 20.5 ± 1 years) was given a battery of personality scales, including the temperament and character inventory-revised, the behavioral inhibition system and behavioral approach system scale, the Beck depression inventory, and the Beck anxiety inventory. Factor analysis of the affect-related personality traits revealed two factors that corresponded to positive (PEM) and negative emotionality (NEM). We found a consistent COMT-by-sex interaction effect on affect-related personality traits. Compared with males with Met/Met alleles, males with Val/Val alleles showed significantly higher scores on NEM, but lower scores on PEM. Females, however, showed an opposite but nonsignificant pattern. Our results supported the role of the COMT gene in personality traits for males and contributed to the growing literature on sex differences in gene-behavior connections.

Epigenetics in Developmental Disorder: ADHD and Endophenotypes

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

The interaction between serotonin receptor 2A and catechol-O-methyltransferase gene polymorphisms is associated with the novelty-seeking subscale impulsiveness

OBJECTIVE

Novelty seeking is a trait that has been consistently associated with problem behaviours. There is evidence for heritability of novelty seeking, but the molecular genetic basis of the trait is still widely unclear.

METHODS

The interaction between polymorphisms of catechol-O-methyltransferase (COMT) and serotonin receptor 2A genes was examined in relation to novelty seeking and its different subscales in healthy Finnish adults. A subsample of 1214 participants derived from a population-based sample was genotyped for the COMT Val158Met (rs4680) and HTR2A T102C (rs6313) genes. Novelty seeking was measured twice, with a 4-year interval, using Cloninger's Temperament and Character Inventory.

RESULTS

The interaction between COMT Val158Met and HTR2A T102C polymorphisms was found to be associated with subscale impulsiveness. T/T carriers of HTR2A T102C polymorphism, that also had Met/Met genotype of COMT Val158Met single nucleotide polymorphism, scored significantly higher on impulsiveness than Val allele carriers (P=0.005).

CONCLUSION

Our results suggest that the interaction between dopaminergic and serotonergic genes might underlie impulsiveness. Together with earlier research our results also stress the importance of considering novelty seeking as a heterogeneous trait with its subscales having different genetic backgrounds.

Scales for the identification of adults with attention deficit hyperactivity disorder (ADHD): a systematic review

Attention deficit hyperactivity disorder (ADHD) is prevalent in the adult population. The associated co-morbidities and impairments can be relieved with treatment. Therefore, several rating scales have been developed to identify adults with ADHD who may benefit from treatment. No systematic review has yet sought to evaluate these scales in more detail. The present systematic review was undertaken to describe the properties, including psychometric statistics, of the currently available adult ADHD rating scales and their scoring methods, along with the procedure for development. Descriptive synthesis of the data is presented and study quality has been assessed by an objective quality assessment tool. The properties of each scale are discussed to make judgements about their validity and usefulness. The literature search retrieved 35 validation studies of adult ADHD rating scales and 14 separate scales were identified. The majority of studies were of poor quality and reported insufficient detail. Of the 14 scales, the Conners' Adult ADHD Rating scale and the Wender Utah Rating Scale (short version) had more robust psychometric statistics and content validity. More research into these scales, with good quality studies, is needed to confirm the findings of this review. Future studies of ADHD rating scales should be reported in more detail so that further reviews have more support for their findings.

DAT1 and COMT effects on delay discounting and trait impulsivity in male adolescents with attention deficit/hyperactivity disorder and healthy controls

Choice impulsivity has been linked to dopamine function and is consistently observed in attention deficit/hyperactivity disorder (ADHD) as a preference for smaller-immediate over larger-delayed rewards using choice-delay paradigms. More sophisticated delay discounting paradigms have yielded inconsistent results. Context and sample characteristics may have contributed to these variations. In this study we examine the effect of type (real vs hypothetical) and magnitude of reward as well as of variation in dopamine genes on choice impulsivity. We selected 36 male adolescents with ADHD-combined subtype (ADHD-CT) and 32 controls (mean age=15.42, SD=2.05) to form four roughly equally sized subgroups on the basis of DAT1(10/6) haplotype dosage (2 copies and <2 copies). Participants, who were also genotyped for the COMT(val158met) and DRD4(48bp-VNTR) polymorphisms, performed a hypothetical and a real-time discounting task and provided self-ratings of trait impulsivity. The ADHD-CT group discounted rewards more steeply than controls only in the hypothetical task, with delay, but not reward magnitude, influencing choices. They also rated themselves as more impulsive compared with controls. DAT1(10/6) dosage and the COMT(Val158Met) genotype predicted trait impulsivity and discounting rates in the hypothetical task, but not in the real-time task. Our results directly link variation in genes putatively influencing dopamine signaling in the prefrontal cortex (COMT(Val158Met)) and the striatum (DAT1(10/6)) with discounting rates in a hypothetical task (but not a real-time task) and self-ratings of trait impulsivity in ADHD-CT and healthy controls. The lack of magnitude effects in the hypothetical task suggests that discounting in this task may be influenced by different processes in ADHD-CT than in healthy controls.

German validation of the Conners Adult ADHD Rating Scales-self-report (CAARS-S) I: factor structure and normative data

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) often persists into adulthood. Instruments for diagnosing ADHD in childhood are well validated and reliable, but diagnosis of ADHD in adults remains problematic. Attempts have been made to develop criteria specific for adult ADHD, resulting in the development of self-report and observer-rated questionnaires. To date, the Conners Adult ADHD Rating Scales (CAARS) are the international standard for questionnaire assessment of ADHD. The current study evaluates a German version of the CAARS self-report (CAARS-S).

METHODS

Eight hundred and fifty healthy German control subjects were recruited to fill out the CAARS-S and to answer questions on sociodemographic variables. Explorative and confirmative factor analyses were conducted to obtain the factor structure for the German model and to replicate the factor structure of the original American model. Analyses on gender, age, and education level were calculated for normative data.

RESULTS

The explorative factor analysis of the German sample results in a six-factor solution that explained 52% of the variance. A confirmative analysis that was based on the 42 items of the original American model showed a high model-fit. Analyses of normative data showed significant influences of age, gender, and education level on the emerging subscales.

CONCLUSION

Even though the explorative factor analysis yields a solution different from the American original, the confirmative factor analysis results in such a high model-fit that use of the American version is justified with respect to international multicenter studies, for which this instrument will be highly valuable.

Molecular genetics of attention deficit hyperactivity disorder

Although twin studies demonstrate that ADHD is a highly heritable condition, molecular genetic studies suggest that the genetic architecture of ADHD is complex. The handful of genome-wide linkage and association scans that have been conducted thus far show divergent findings and are, therefore, not conclusive. Similarly, many of the candidate genes reviewed here (ie, DBH, MAOA, SLC6A2, TPH-2, SLC6A4, CHRNA4, GRIN2A) are theoretically compelling from neurobiological systems perspective but available data are sparse and inconsistent. However, candidate gene studies of ADHD have produced substantial evidence implicating several genes in the etiology of the disorder, with meta-analyses supportive of a role of the genes coding for DRD4, DRD5, SLC6A3, SNAP-25, and HTR1B in the etiology of ADHD.

Dopamine and serotonin systems modify environmental effects on human behavior: a review

The relative influences of genetic and environmental factors in the development of human behavior have been a long-term topic for an intense debate. Recent behavioral genetic studies suggest focusing on the joint effect of genes and environment, and especially on the life-course developmental interplay between nature and nurture. Vulnerability to environmental adversities and sensitivity to its benefits may be conditional on genetic background, and regarding psychological outcomes, these kinds of gene x environment interactions may be of higher importance than direct gene-trait associations. In our recent series of studies, we have shown that different variants of serotonergic and dopaminergic genes may moderate the influence of environmental conditions on a range of psychological outcomes, i.e. temperament, depression, hostility, and educational attainment. These studies suggest that depending on their genotype, people may be differentially sensitive to the environmental conditions they encounter. In the light of these results it seems highly plausible that the effects of genes may become evident only when studied in the context of environmental factors.

Catechol-O-methyltransferase Val 158 Met polymorphism and antisaccade eye movements in schizophrenia

The catechol-O-methyltransferase (COMT) enzyme catabolizes dopamine. The val(158)met single nucleotide polymorphism (rs4680) in the COMT gene has received considerable attention as a candidate gene for schizophrenia as well as for frontally mediated cognitive functions. Antisaccade performance is a good measure of frontal lobe integrity. Deficits on the task are considered a trait marker for schizophrenia. The aim of this study was to investigate the association of COMT val(158)met polymorphism with antisaccade eye movements in schizophrenia patients and healthy controls. Schizophrenia patients (N = 105) and healthy controls (N = 95) underwent infrared oculographic assessment of antisaccades. Subjects were genotyped for COMT val(158)met and divided into 3 groups according to genotype (val/val, val/met, and met/met). Patients displayed significantly more reflexive errors, longer and more variable latency, and lower amplitude gain than controls (all P < 0.02). A greater number of val(158) alleles was associated with shorter (P = 0.045) and less variable (P = 0.028) antisaccade latency and, nonsignificantly, with lower reflexive error rate (P = 0.056). None of these variables showed a group-by-genotype interaction (P > 0.1). There were no significant associations of genotype with measures of amplitude gain or spatial error (P > 0.2). The results suggest that COMT val(158) carrier status is associated with better performance on the antisaccade task. Possible explanations of this finding are discussed.

Self-reported adult attention-deficit/hyperactivity disorder symptoms among college students

OBJECTIVE

Report the distribution of scores from the Adult ADHD Self-Report Scale (ASRS) and estimate the prevalence of self-reported attention-deficit/hyperactivity disorder (ADHD) symptoms as compared to clinical diagnoses.

PARTICIPANTS

Participants were 1,080 college students, divided into 3 groups: (1) no ADHD diagnosis (n = 972), (2) diagnosed with ADHD but no current pharmacologic treatment (n = 54), and (3) diagnosed with ADHD with current pharmacologic treatment (n = 54).

METHODS

The ASRS was administered during the fourth annual interview of an ongoing longitudinal cohort study.

RESULTS

As expected, individuals who were never clinically diagnosed with ADHD had lower ASRS scores (M = 4.0, SD = 3.3) than individuals diagnosed with ADHD who were either under current pharmacologic treatment (M = 7.9, SD = 4.0) or not under treatment (M = 6.3, SD = 3.7). Overall, 10.3%wt of individuals without an existing clinical diagnosis of ADHD had high levels of ADHD symptoms.

CONCLUSIONS

A substantial minority of undiagnosed individuals may benefit from a clinical assessment for ADHD.

Attention-deficit/hyperactivity disorder phenotype is influenced by a functional catechol-O-methyltransferase variant

The catechol-O-methyltransferase gene (COMT) plays a crucial role in the metabolism of catecholamines in the frontal cortex. A single nucleotide polymorphism (Val(158)Met SNP, rs4680) leads to either methionine (Met) or valine (Val) at codon 158, resulting in a three- to fourfold reduction in COMT activity. The aim of the present study was to assess the COMT Val(158)Met SNP as a risk factor for attention-deficit/hyperactivity disorder (ADHD), ADHD symptom severity and co-morbid conduct disorder (CD) in 166 children with ADHD. The main finding of the present study is that the Met allele of the COMT Val(158)Met SNP was associated with ADHD and increased ADHD symptom severity. No association with co-morbid CD was observed. In addition, ADHD symptom severity and early adverse familial environment were positive predictors of lifetime CD. These findings support previous results implicating COMT in ADHD symptom severity and early adverse familial environment as risk factors for co-morbid CD, emphasizing the need for early intervention to prevent aggressive and maladaptive behavior progressing into CD, reducing the overall severity of the disease burden in children with ADHD.

The effect of ADHD symptoms on performance monitoring in a non-clinical population

Recent studies suggested deficits in error processing in patients with Attention Deficit Hyperactivity Disorder (ADHD), but some inconsistencies are still present. Using the ADHD screening questionnaire, the Adult ADHD Self-Report Scale, we investigated the association between the amount of inattention and hyperactivity/impulsivity symptoms in a non-clinical population of healthy students (n=56) and the neural correlates of error processing measured with event-related potentials. We found reduced amplitudes of error-positivity (Pe) with increasing symptoms of inattention, but no correlation with error-related negativity. These results suggest that attention deficits reduce the conscious evaluation of an error as reflected by reduced Pe amplitudes.