Effect of alpha2A-adrenoceptor C-1291G genotype and maltreatment on hyperactivity and inattention in adolescents

Genetics of child aggression, a systematic review

Excessive and persistent aggressiveness is the most common behavioral problem that leads to psychiatric referrals among children. While half of the variance in childhood aggression is attributed to genetic factors, the biological mechanism and the interplay between genes and environment that results in aggression remains elusive. The purpose of this systematic review is to provide an overview of studies examining the genetics of childhood aggression irrespective of psychiatric diagnosis. PubMed, PsycINFO, and MEDLINE databases were searched using predefined search terms for aggression, genes and the specific age group. From the 652 initially yielded studies, eighty-seven studies were systematically extracted for full-text review and for further quality assessment analyses. Findings show that (i) investigation of candidate genes, especially of MAOA (17 studies), DRD4 (13 studies), and COMT (12 studies) continue to dominate the field, although studies using other research designs and methods including genome-wide association and epigenetic studies are increasing, (ii) the published articles tend to be moderate in sizes, with variable methods of assessing aggressive behavior and inconsistent categorizations of tandem repeat variants, resulting in inconclusive findings of genetic main effects, gene-gene, and gene-environment interactions, (iii) the majority of studies are conducted on European, male-only or male-female mixed, participants. To our knowledge, this is the first study to systematically review the effects of genes on youth aggression. To understand the genetic underpinnings of childhood aggression, more research is required with larger, more diverse sample sets, consistent and reliable assessments and standardized definition of the aggression phenotypes. The search for the biological mechanisms underlying child aggression will also benefit from more varied research methods, including epigenetic studies, transcriptomic studies, gene system and genome-wide studies, longitudinal studies that track changes in risk/ameliorating factors and aggression-related outcomes, and studies examining causal mechanisms.

Common and Unique Genetic Background between Attention-Deficit/Hyperactivity Disorder and Excessive Body Weight

Comorbidity studies show that children with ADHD have a higher risk of being overweight and obese than healthy children. This study aimed to assess the genetic alternations that differ between and are shared by ADHD and excessive body weight (EBW). The sample consisted of 743 Polish children aged between 6 and 17 years. We analyzed a unique set of genes and polymorphisms selected for ADHD and/or obesity based on gene prioritization tools. Polymorphisms in the KCNIP1, SLC1A3, MTHFR, ADRA2A, and SLC6A2 genes proved to be associated with the risk of ADHD in the studied population. The COMT gene polymorphism was one that specifically increased the risk of EBW in the ADHD group. Using the whole-exome sequencing technique, we have shown that the ADHD group contains rare and protein-truncating variants in the FBXL17, DBH, MTHFR, PCDH7, RSPH3, SPTBN1, and TNRC6C genes. In turn, variants in the ADRA2A, DYNC1H1, MAP1A, SEMA6D, and ZNF536 genes were specific for ADHD with EBW. In this way, we confirmed, at the molecular level, the existence of genes specifically predisposing to EBW in ADHD patients, which are associated with the biological pathways involved in the regulation of the reward system, intestinal microbiome, and muscle metabolism.

ADHD and Exposure to Maltreatment in Children and Youth: a Systematic Review of the Past 10 Years

PURPOSE OF THE REVIEW

The purpose of the current paper was to review and summarize the literature on ADHD and maltreatment over the past 10 years.

RECENT FINDINGS

The majority of research on ADHD and exposure to maltreatment focuses on the high rates of comorbidity, including international studies from Asia, South America, North America, and Europe. Longitudinal studies showed that early exposure to maltreatment is a risk factor for ADHD symptoms later in development; however, this finding was not consistent. There were some preliminary studies on the neurological and genetic mechanisms underlying the link between ADHD and exposure to maltreatment. Finally, ADHD and exposure to maltreatment were found to have an additive effect on clinically salient outcomes (e.g., aggression, suicide attempts). Results from the review have direct clinical and future implications, including the need to understand the effect of comorbid ADHD and exposure to maltreatment in treatment studies.

Low cholesterol levels in children predict impulsivity in young adulthood

OBJECTIVE

Severe behavioural issues such as impulsive action and suicide have since long been associated with low levels of cholesterol. While it is known that cholesterol plays a role in neural development and hence low levels of serum lipids could have long-term effects on behaviour, no longitudinal studies showed the association of serum lipids levels with impulsivity. We aimed to examine the prognostic properties of serum lipid levels during childhood and adolescence on measures of impulsivity during early adulthood in a representative birth cohort sample.

METHODS

We have investigated whether serum lipid levels measured at 9, 15, 18 and 25 years of age have an association with impulsivity in 25 years old young adults. This analysis was based on data of the birth cohort representative samples of the Estonian Children Personality Behaviour and Health Study (original n = 1238). Impulsivity was self-reported with the Adaptive and Maladaptive Impulsivity Scale.

RESULTS

Total and low-density lipoprotein (LDL) cholesterol measured in boys aged 9, 15 and 18 years predicted disinhibition and thoughtlessness in 25-year-old young adults. High scores of disinhibition were associated with low total and LDL cholesterol levels in males but, while less consistently, with high total and LDL cholesterol levels in females. Cross-sectional analysis did not result in systematic outcomes.

CONCLUSIONS

Serum lipid levels could have an impact on the development of Maladaptive Impulsivity starting from an early age. This effect of cholesterol continues throughout adolescence into young adulthood.

Nitric oxide synthase genotype interacts with stressful life events to increase aggression in male subjects in a population-representative sample

Nitric oxide signalling has been implicated in impulsive and aggressive traits and behaviours in both animals and humans. In the present study, we investigated the effects of a functional variable number of tandem repeats (VNTR) polymorphism in exon 1f (ex1f) of the nitric oxide synthase 1 (NOS1) gene (NOS1 ex1f-VNTR) and stressful life events on aggressive behaviour in population representative sample of adolescents followed up from third grade to 25 years of age. We studied the younger cohort of the longitudinal Estonian Children Personality, Behaviour and Health Study (subjects in the last study wave n = 437, males n = 193; mean age 24.8 ± 0.5 years). Aggressive behaviour was rated at age 25 with the Illinois Bully Scale and Buss-Perry Aggression Questionnaire. Life history of aggression was evaluated in a structured interview. Stressful life events and family relationships were self-reported at age 15. The hypothesized risk genotype (homozygosity for the short allele) was associated with higher levels of aggression in males (statistical significance withstanding the multiple correction procedure). Exposure to stressful life events or adverse family relationships was associated with increased aggressive behaviour in subjects homozygous for either of the alleles, and these associations were mostly observed in males. However, these associations in these stratified analyses did not survive correction for multiple testing. Aggressiveness was relatively unaffected by the NOS1 ex1f-VNTR genotype in the female subjects even when taking exposure to childhood adversity into account. Our findings support the hypothesized involvement of a functional NOS1 polymorphism on aggression in a population representative sample of young adults.

Family environment interacts with CRHR1 rs17689918 to predict mental health and behavioral outcomes

BACKGROUND

Corticotrophin-releasing hormone receptor-1 gene (CRHR1) variants have been implicated in mental health. However, little is known of the effects of CRHR1 on long-term mental health and behavior in presence of environmental stressors. We assess the effects of CRHR1 variant (rs17689918)-by-environment interactions on emotionality and behavioral traits, including anxiety, depression, aggression and antisocial behaviors. We also determine effects of rs17689918-by-environment-by-sex interactions on the above-mentioned outcomes.

METHODS

Genotypic assessments were carried out in 564 children (mean age 10 years, 52.5% females) from the ongoing longitudinal Estonian Children Personality Behaviour and Health Study (ECPBHS). Information on stressful life events and family relationships were available at baseline and information on behavioral and mental health outcomes (self- and parent-reports) were available at follow-up ages of 18 and 25 years. ANOVAs were used to determine associations of two-way CRHR1-by-environment and three-way CRHR1-by-sex-by-environment interactions on behavioral and mental health outcomes.

RESULTS

Two-way CRHR1 interaction effects showed associations between low familial warmth and hostility in individuals with the GG genotype. Associations of low familial warmth with aggression, of higher number of stressful life events with aggression, and of stressful live events with anxious-depressive symptoms were noted in male A-allele carriers and female GG homozygotes.

CONCLUSION

CRHR1-by-familial environment interactions influence both outwardly-directed aggression as well as mood and anxiety disorder symptoms in a sex-specific manner. The type of environmental stressor can also influence effects of CRHR1 on behavioral and mental health outcomes.

Effectiveness of a universal classroom-based preventive intervention (PAX GBG): A research protocol for a matched-pair cluster-randomized controlled trial

INTRODUCTION

The PAX Good Behavior Game (PAX GBG) is a universal classroom-based program that promotes children's mental health. In Estonia, the intervention is delivered to first grade students (aged seven to eight) within the regular school curriculum. The current work describes a protocol for a cluster-randomized controlled trial (RCT) of the PAX GBG conducted in Estonia.

DESIGN AND METHODS

This is an ongoing, pragmatic, two-year, matched-pair, cluster-RCT conducted in Estonian elementary schools. Schools were matched to pairs based on their geographical location and number of students per classroom. One school in each pair was randomly selected to receive the intervention and the other placed on a wait-list as a control. 42 schools provided baseline data during the autumn of 2016. Data is collected at two more points in time - seven months and 19 months post-baseline. Outcomes of children's mental health and behavior are measured by the teacher- and parent-rated Strengths and Difficulties Questionnaire, parent-rated Swanson, Nolan, and Pelham - IV Questionnaire and the Go/No-Go task completed by children. Teachers also rate their self-efficacy and overall classroom behavior.

DISCUSSION

This study aims to test the effectiveness of the intervention in Estonian classrooms with a newer version of the rigorously tested GBG program. To our knowledge, this study is the first to measure the effects of the intervention on children's inhibitory control, which has been associated with externalizing problems in the literature. The results from this trial will provide further understanding into how the program influences children's well-being and self-control.

TRIAL REGISTRATION

ClinicalTrials.gov registry (NCT02865603).

Nice guys: Homozygocity for the TPH2 -703G/T (rs4570625) minor allele promotes low aggressiveness and low anxiety

BACKGROUND

Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of serotonin. We examined whether the TPH2 polymorphism -703G/T (rs4570625) is associated with aggressiveness and impulsivity, and the prevalence of psychiatric disorders, in a population-representative sample.

METHODS

We used self and proxy reports on aggressive behaviour in the younger birth cohort of the longitudinal Estonian Children Personality, Behaviour and Health Study collected at age 25, and earlier collected impulsivity and related data of both ECPBHS cohorts.

RESULTS

The TT homozygous males reported less aggressive behaviour in the Life History of Aggression interview at age 25. They also had significantly lower scores in Illinois Bully Scale peer reports, and less ADHD symptoms rated by teachers both at ages 9 and 15. The TT homozygotes of both sexes had the lowest Maladaptive Impulsivity at ages 18 and 25, and the highest Adaptive Impulsivity at age 25. The TT homozygotes also had low depressiveness and trait anxiety by age 25, and the odds ratio for the prevalence of anxiety disorders was 9.38 for the G-allele carriers.

LIMITATIONS

The main limitation of the study is the naturally occurring low number of subjects with the TT genotype.

CONCLUSIONS

Subjects with the TPH2 rs4570625 TT genotype, especially males, exhibit less aggression and a favourable impulsivity profile, and develop anxiety disorders by young adulthood less often.

BDNF Val66Met genotype and neuroticism predict life stress: A longitudinal study from childhood to adulthood

The brain-derived neurotrophic factor gene (BDNF) Val66Met polymorphism and life stress have been associated with negative emotionality (e.g., neuroticism), but relevant evidence is far from unequivocal. Possible confounding factors include the type and timing of stressful events measured, such as childhood adversity vs. recent stressful events, and variable gene × environment interactions. The aim of this study was to longitudinally assess the BDNF Val66Met polymorphism and environment interaction effect on neuroticism in a population representative sample, depending upon the type of stress, gender and family relations. In the original older cohort of the Estonian Children Personality Behavior and Health Study (ECPBHS, n=593), neuroticism was measured at age 15 (parental assessment), 18 and 25 (self-assessments). Childhood stress was reported at age 15, quality of family relations was measured at age 18, and recent stressful life events at age 25. The BDNF Val66Met polymorphism interacted with recent stressful life events, but not with childhood adversities, to impact neuroticism. Interestingly, in female participants, neuroticism at age 18 predicted future stressful life events dependent upon genotype: individuals with Val/Val genotype and high neuroticism experienced higher, but Met-allele carriers with high neuroticism lower stress exposure at age 25. Similar tendencies were observed using parental assessments at age 15. The protective effect of Met-allele in the high stress exposure group could result from better early family environment. In conclusion, we herewith provide further evidence for a role of BDNF gene variance contributing to plasticity in response to environmental demands.

Perception of emotion in facial stimuli: The interaction of ADRA2A and COMT genotypes, and sex

Emotional facial stimuli are important social signals that are essential to be perceived and recognized in order to make appropriate decisions and responses in everyday communication. The ability to voluntarily guide attention to perceive and recognize emotions, and react to them varies largely across individuals, and has a strong genetic component (Friedman et al., 2008). Two key genetic variants of the catecholamine system that have been related to emotion perception and attention are the catechol-O-methyl transferase genetic variant (COMT Val158Met) and the α2A-receptor gene promoter polymorphism (ADRA2A C-1291G) accordingly. So far, the interaction of the two with sex in emotion perception has not been studied. Multilevel modeling method was applied to study how COMT Val158Met, ADRA2A C-1291G and sex are associated with measures of emotion perception in a large sample of young adults. Participants (n=506) completed emotion recognition and behavioral emotion detection tasks. It was found that COMT Val158Met genotype in combination with the ADRA2A C-1291G and sex predicts emotion detection, and perception of valence and arousal. In simple visual detection, the ADRA2A C-1291G G-allele leads to slower detection of a highly arousing face (scheming), which is modulated by each additional COMT Val158Met Met-allele and male sex predicting faster responses. The combination of G-allele, Met-allele and male sex also predicts higher perceived negativity in sad faces. No effects of C-1291G, Val158Met, and sex were found on verbal emotion recognition. Applying the findings to study the interplay between catecholamine-O-methyl transferase activity and α2A-receptors in emotion perception disorders (such as ADHD, autism and schizophrenia) in men and women would be the next step towards understanding individual differences in emotion perception.

[A pharmacogenetic analysis of dopaminergic and opioidergic genes in opioid addicts treated with the combination of naltrexone and guanfacine]

AIM

To evaluate an effect of opioid receptor and dopamine system gene polymorphisms on the efficacy of combined treatment with oral naltrexone and guanfacine in a randomized double blinded double dummy placebo controlled clinical trial.

MATERIAL AND METHODS

Three hundred and one patients with opioid dependence were randomized into 4 treatment groups: naltrexone 50 mg/day + guanfacine 1 mg/day (N+G); naltrexone + placebo guanfacine (N+GP); placebo naltrexone + guanfacine (NP+G); double placebo (NP+GP). The primary outcome was treatment retention. All enrolled participants were genotyped for polymorphisms in the following genes: mu- (OPRM1), kappa-opioid receptors (OPRK1), catechol-O-methyltransferase (COMT), dopamine receptors types 2 (DRD2) and 4 (DRD4), dopamine-beta-hydroxylase, and dopamine transporter (SLC6A3, DAT1) and alpha-2-adrenoreceptor (ADRA2A) a pharmacological target of guanfacine.

RESULTS

The efficacy of the combination of naltrexone and guanfacine was comparable to naltrexone monotherapy. Regardless of treatment, several gene polymorphisms were associated with higher chance to complete the treatment program: allele Т DRD4 - 521 С/Т (rs1800955) (р=0.039; OR (95% CI)=3.7 (1.1-12.7); log-rank test: р=0.01); allele С DRD2 С957Т (rs6277) (р=0.03; HR=0.6 (0.34-0.95); genotype combination: DRD4 VNTR (LL) + OPRM1 A118G (rs1799971) (AA), р=0.051; DRD2 C957T (ТТ) + OPRM1 (rs1074287) (СС), р=0.025; DRD2 - 141С (II) + OPRM1 (rs510769) (АА), р=0.035; DBH Fau(СС) + OPRM1 (rs1074287) (СС), р=0.0497. Regardless of treatment several polymorphisms were associated with high risk of relapse: allele Т (rs510769) OPRM1 (р=0.053), allele А (rs1799971, A118G) OPRM1 (р=0.056), allele S exon III 48 bp DRD4 VNTR (р=0.001; HR=3.1 (ДИ 95% 1.57-6.18); genotype combinations: DRD4 - 521 С/Т (ТТ) + DRD2 Nco I (TT), р=0.026; DRD4 -521 С/Т (ТТ) + DRD2 -141 С (II), р=0.011; DRD4 - 521 С/Т (ТТ) + OPRM1 A118G (rs1799971) (AA), р=0.011; DRD2 Nco I(ТТ) + ADRA2A (СС), р=0.012; DRD2 Nco I(ТТ) + OPRM1 A118G (AA), р=0.02. The effects dependent on the treatment group were as follows: 1) in the N+G group, patients with the DRD4 -521 С/Т TT genotype had higher probability of completion of treatment program in comparison with other genotypes (CC and CT) (log-rank test: p=0.002); 2) in NP + GP group, patients with the OPRM1 rs510769 T allele had higher risk of relapse compared to the genotype GG (p=0.008) (FDR p<0.0125).

CONCLUSION

The additive effect of opioid receptor genes and dopaminergic system genes on outcomes of treatment opioid dependence with oral naltrexone and guanfacine was shown. Pharmacological effects of naltrexone and guanfacine were associated with genetic variants of the DRD4 - 521C/T polymorphism, since its effect was shown only in the N+G group. The effect of the OPRM1 rs510769 polymorphism was demonstrated in the double placebo group that was associated with personality traits (temperament, character) and determined compliance. Genetic analysis is useful for determining potential responders to treatment of opioid dependence; genotyping can increase the efficacy of pharmacotherapy.

Genetic and environmental contributions to the association between attention deficit hyperactivity disorder and alcohol dependence in adulthood: A large population-based twin study

Previous research indicates that attention deficit hyperactivity disorder (ADHD) frequently co-occurs with alcohol dependence; however, the extent to which shared genetic risk factors underpin this association remains unclear. The aim of this study is to investigate the relative importance of genetic, shared, and nonshared environmental factors for the overlap between ADHD and alcohol dependence in adults. Almost 18,000 adult twins aged 20-45 years, from more than 12,000 twin pairs (5,420 complete pairs), from the population-representative Swedish Twin Registry, were included. Self-ratings were used to assess symptoms of ADHD and alcohol dependence. Twin analysis was used to determine the role of additive genetic (A), shared (C), and nonshared environmental (E) factors. As a result, we found a significant association between ADHD and alcohol dependence (odds ratio 3.58; 95% confidence interval, 2.85-4.49). Twin analysis suggested that shared genetic risk factors explained 64% of the overlap between ADHD and alcohol dependence. Nonshared environmental factors accounted for the remaining 36%, whereas the contribution of shared environmental factors was minimal. We found no support for statistically significant sex differences in the overlap between ADHD and alcohol dependence. In conclusion the overlap between ADHD and alcohol dependence in adulthood was largely explained by shared genetic risk factors. This is an important step toward understanding the underlying nature of the risk of alcohol dependence in patients with ADHD and suggests that individuals with ADHD and their family members are important targets for alcohol prevention and treatment. © 2015 Wiley Periodicals, Inc.

Neuropeptide S receptor gene variant and environment: contribution to alcohol use disorders and alcohol consumption

The functional polymorphism Asn(107) Ile (rs324981, A > T) of the neuropeptide S receptor (NPSR1) gene is involved in the modulation of traits that affect alcohol use. Hence, we have examined whether the NPSR1 A/T polymorphism is associated with alcohol use disorders (AUD) and alcohol use in a population-representative sample. Lifetime AUD were assessed by the MINI psychiatric interview (n = 501) in the older cohort of the longitudinal Estonian Children Personality Behaviour and Health Study at age 25. Alcohol use, environmental adversities and personality were reported by both the younger (original n = 583) and the older cohort (original n = 593) in three study waves. NPSR1 associations with AUD and alcohol use differed by sex. In females, both AUD [odds ratio (OR) = 7.20 (0.94-55.0), P = 0.029] and harmful alcohol use were more prevalent in A-allele carriers. In contrast, in males, AUD was more frequent in T-allele carriers [OR = 2.75 (1.19-6.36), P = 0.017], especially if exposed to adverse environments at age 15 [OR = 10 (1.18-84.51), P = 0.019]. Alcohol use was higher in male T-allele carriers at ages 15 and 18 as well. Similarly to females, however, the risk allele for higher alcohol use for males at age 25 was the A-allele. Many of the effects on alcohol use were explained by genotype effects on measures of personality. In the general population, the NPSR1 Asn(107) Ile polymorphism is associated with AUD and alcohol consumption, dependent on sex, environment and age. The results are in line with the impulsivity and personality regulating role of the NPSR1.

Interaction of the neuropeptide S receptor gene Asn¹⁰⁷Ile variant and environment: contribution to affective and anxiety disorders, and suicidal behaviour

Neuropeptide S is involved in anxiety and arousal modulation, and the functional polymorphism Asn107Ile (rs324981, A > T) of the neuropeptide S receptor gene (NPSR1) is associated with panic disorder and anxiety/fear-related traits. NPSR1 also interacts with the environment in shaping personality and impulsivity. We therefore examined whether the NPSR1 A/T polymorphism is associated with affective and anxiety disorders in a population-representative sample. Lifetime psychiatric disorders were assessed by MINI interview (n = 501) in the older cohort of the longitudinal Estonian Children Personality, Behaviour and Health Study (ECPBHS). Anxiety (STAI), self-esteem (RSES), depression (MÅDRS), suicide attempts and environmental factors were self-reported in both the younger (original n = 583) and the older cohort (original n = 593). Most of the NPSR1 effects were sex-specific and depended on environmental factors. Females with the functionally least active NPSR1 AA genotype and exposed to environmental adversity had affective/anxiety disorders more frequently; they also exhibited higher anxiety and depressiveness, and lower self-esteem. Female AA homozygotes also reported suicidal behaviour more frequently, and this was further accentuated by adverse family environment. In the general population, the NPSR1 A/T polymorphism together with environmental factors is associated with anxious, depressive and activity-related traits, increased prevalence of affective/anxiety disorders and a higher likelihood of suicidal behaviour.

A functional NPSR1 gene variant and environment shape personality and impulsive action: a longitudinal study

Neuropeptide S and its receptor NPSR1 are involved in the regulation of arousal, attention and anxiety. We examined whether the NPSR1 gene functional polymorphism Asn¹⁰⁷Ile (rs324981, A>T) influences personality, impulsivity, and attention-deficit/hyperactivity disorder (ADHD)-related symptoms in a population-representative sample, and whether any eventual associations depend on age, sex, family relations and stressful life events (SLE). We used self-reports or teachers' ratings for both the younger (n=593) and older (n=583) cohort of the longitudinal Estonian Children Personality, Behaviour and Health Study. Males with the TT genotype displayed more ADHD-related symptoms. Adaptive impulsivity and Extraversion increased the most from age 18 to 25. While highest increases were observed in AA men, TT women exhibited the largest decreases. For participants with the AA genotype, Warmth in family was inversely associated with Neuroticism, and positively associated with Extraversion and Adaptive impulsivity. High exposure to SLE increased impulsivity and ADHD scores in TT genotype subjects. We conclude that the NPSR1 A/T polymorphism is associated with impulsivity, ADHD symptoms and personality, mirroring the activity- and anxiety-mediating role of NPSR1. Heterozygous individuals were the least sensitive to environmental factors, whereas subjects with the AA genotype and TT genotype reacted to different types of environmental adversities.

Mitigating aggressiveness through education? The monoamine oxidase A genotype and mental health in general population

OBJECTIVE

Monoamine oxidase A (MAOA) gene promoter region includes a variable number of tandem repeat (VNTR) associated with antisocial behaviour in adverse environment. We have examined the effect of the MAOA-uVNTR on mental health and academic success by using a population representative sample and a longitudinal design.

METHODS

The data of the older cohort (n = 593, aged 15 years at the original sampling) of the longitudinal Estonian Children Personality, Behaviour and Health Study (ECPBHS) were used. Follow-ups were conducted at ages 18 and 25 years. Aggressiveness, inattention and hyperactivity were reported by class teachers or, at older age, self-reported. Stressful life events, psychological environment in the family and interactions between family members were self-reported. Data of general mental abilities and education were obtained at the age of 25, and lifetime psychiatric disorder assessment was carried out with the Mini-International Neuropsychiatric Interview (MINI) interview.

RESULTS

MAOA-uVNTR genotype had no independent effect on aggressiveness, hyperactive and inattentive symptoms, and neither was there a genotype interaction with adverse life events. Interestingly, the proportion of male subjects with higher education by the age of 25 was significantly larger among those with MAOA low-activity alleles (χ² = 7.13; p = 0.008). Logistic regression revealed that MAOA low-activity alleles, higher mental abilities, occurrence of anxiety disorders and absence of substance-use disorder were significant independent predictors for higher education in male subjects.

CONCLUSIONS

In a population representative sample of young subjects, the MAOA-uVNTR 'risk genotype' predicted better life outcomes as expressed in higher level of education.

Candidate gene associations with withdrawn behavior

BACKGROUND

Social withdrawal is a core neuropsychiatric phenomenon in developmental psychopathology. Its presence predicts psychopathology across many domains, including depression, psychosis, autism, anxiety, and suicide. Withdrawn behavior is highly heritable, persistent, and characteristically worsens without intervention. To date, few studies have successfully identified genetic associations with withdrawn behavior, despite the abundance of evidence of its heritability. This may be due to reliance of categorical over dimensional measures of the behaviorally inhibited phenotype. The aim of this study is to identify associations between known psychiatric candidate genes and a dimensionally derived measure of withdrawn behavior.

METHODS

Genetic information was collected on 20 single-nucleotide polymorphisms (SNPs) from a custom-designed SNP chip and TAQMAN arrays of 4 variable number of tandem repeat (VNTR) genes for 551 individuals from 187 families. Linear mixed modeling was employed to examine the relationship between genotypes of interest and Child Behavior Checklist (CBCL) Withdrawn Behavior Subscale Score (WBS) while controlling for gender and age through multiple linear regressions.

RESULTS

Withdrawn behavior was highly associated with polymorphism rs6314 of the serotonin receptor 2A (HTR2A) [p = .009, estimate = 0.310 (bootstrap 95% CI 0.155-0.448), bootstrap p = .001] and rs1800544 of the alpha 2-adrenergic (ADRA2A) [p = .001, estimate = -0.310 (bootstrap 95% CI -0.479 to -0.126), bootstrap p = .001] genes after correction for gender and age. The association between withdrawn behavior and ADRA2A was stronger for younger children.

CONCLUSIONS

HTR2A and ADRA2A genes are associated with withdrawn behavior. This reinforces the role of catecholaminergic genes in the heritability of withdrawn behavior.

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.

Preventing risky driving: A novel and efficient brief intervention focusing on acknowledgement of personal risk factors

Impulsive personality is an important predictor of risky driving. Acknowledging their impulsive tendencies may help novice drivers to drive more safely. The aim of this study was to evaluate the efficacy of a novel brief intervention targeting novice drivers' risky behavior in traffic, taking into account potential moderator effects. Driving school students (n=1866) were divided into an intervention group and a control group. The intervention consisted of a lecture and group work (1.5h). Subjects' traffic offenses and crashes were monitored during the following year using police and traffic insurance fund databases. The groups were similar in their baseline characteristics. The intervention group had half as many speeding violations in the year following the intervention compared with the controls. The proportion of speeders was significantly lower in the intervention group compared with the control group in subgroups of subjects with medium cognitive abilities and low or medium BIS-11 impulsiveness levels. In alpha(2A)-adrenoceptor gene (ADRA2A) G allele carriers, general traffic risk and speeding decreased in response to the intervention, unlike in subjects with the CC genotype. It is concluded that brief interventions that are integrated into the driving education program and focus on personal psychological risk factors may be effective for improving traffic safety.

Association of positive and negative parenting behavior with childhood ADHD: interactions with offspring monoamine oxidase A (MAO-A) genotype

Relatively little is known about the potential interplay between genetic and environmental influences on attention-deficit/hyperactivity disorder (ADHD), including gene-environment interaction (G×E). There is evidence that parenting behavior interacts with offspring genotype in the development of externalizing problems, but studies have largely focused on explicit maltreatment rather than differentiated measures of parenting behavior, including positive and negative parenting. We tested the interactive effects of the 30-base pair variable number tandem repeat (VNTR) polymorphism of the monoamine oxidase A gene (MAO-A) with positive and negative parenting behavior on parent- and teacher ratings of inattention and hyperactivity symptoms among 150 6-9 year-old boys with and without ADHD. Negative parenting predicted parent and teacher ratings of inattention symptoms, but only among boys with high-activity MAO-A genotype. MAO-A genotype did not moderate the association of positive parenting and parent- and teacher ratings of ADHD. We discuss the potential role of interactive exchanges between parenting behavior and child genotype in the development and persistence of ADHD and related behavior problems.

Effects of the serotonin transporter (5-HTTLPR) and α2A-adrenoceptor (C-1291G) genotypes on substance use in children and adolescents: a longitudinal study

RATIONALE AND OBJECTIVE

Twin studies suggest that substance use initiation in children and adolescents is determined primarily by environmental influences, whereas the establishment of use patterns is strongly controlled by genetic factors. The present study analysed the effects of the serotonin transporter promoter polymorphism [5-HT transporter gene-linked polymorphic region (5-HTTLPR)] and the α(2A)-adrenoceptor C-1291G genotype (ADRA2A C-1291G) as well as their interaction effects on alcohol, tobacco and drug use from preadolescence to the late adolescence.

METHODS

Initial sample of 9-year-old children of Estonian Children Personality Behaviour and Health Study (n = 583) was recalled at ages 15 and 18. Participants reported in all waves how frequently they smoked and used alcohol and illicit drugs.

RESULTS

5-HTTLPR had age-dependent effects on alcohol, tobacco and drug use: substance use did not differ by genotype at age 9, but at age 15, the participants with the short (s)/s genotype had higher tobacco use, and at age 18, they were more active alcohol, drug and tobacco users. Effects of ADRA2A C-1291G on drug use were dependent on gender, age and 5-HTTLPR. Males (age 18) with ADRA2A CG genotype, when compared to other participants, tended to have higher drug use especially when they had s/s genotype of 5-HTTLPR.

CONCLUSIONS

Our results reveal that expression of genetic vulnerability for substance use in children and adolescents may depend on age, gender, interaction of genes, and type of substance.

A functional NOS1 promoter polymorphism interacts with adverse environment on functional and dysfunctional impulsivity

RATIONALE

Neuronal nitric oxide synthase (NOS1) knockout results in increased impulsive aggression in mice under adverse housing conditions. In line with this, we have previously shown that a functional promoter polymorphism of NOS1, termed NOS1 ex1f-VNTR, is associated with impulsivity-related traits and related disorders.

OBJECTIVE

This study aims to examine whether adverse environment interacts with the risk allele on impulsivity-related measures.

METHODS

We here studied a population-based cohort of Estonian pupils, recruited at the age of 9 years and followed up for another 9 years. For 435 subjects, measures on impulsivity (Adaptive and Maladaptive Impulsivity Scale, BIS-11, Stop Signal data, and Visual Comparison Test, VCT), environmental conditions (stressful life events and family environment), and NOS1 ex1f-VNTR genotype were available.

RESULTS

We found a genotype main effect in that presence of a short NOS1 ex1f-VNTR allele was associated with higher levels of adaptive impulsivity, especially in males, but also worse performance in the VCT and the Stop Signal test. Both stressful life events as well as adverse family environment interacted with the risk genotype to increase maladaptive impulsivity.

CONCLUSIONS

This study provides further evidence that short alleles of NOS1 ex1f-VNTR go along with impulsive behavior. In the absence of adverse environmental conditions, this may lead to a beneficial effect as functional forms of impulsivity are affected. This however is reversed under negative conditions, as dysfunctional impulsivity is increased under these circumstances. This data provides evidence that NOS1 ex1f-VNTR is subject to balancing selection potentially explaining persistence of the risk allele in the population.