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Recent studies have emphasized an important role for neurotrophins, such as brain-derived neurotrophic factor (BDNF), in regulating the plasticity of neural circuits involved in the pathophysiology of stress-related diseases. The aim of the present study was to examine the interplay of the BDNF Val(66)Met and the serotonin transporter promoter (5-HTTLPR) polymorphisms in moderating the impact of early-life adversity on BDNF plasma concentration and depressive symptoms. Participants were taken from an epidemiological cohort study following the long-term outcome of early risk factors from birth into young adulthood. In 259 individuals (119 males, 140 females), genotyped for the BDNF Val(66)Met and the 5-HTTLPR polymorphisms, plasma BDNF was assessed at the age of 19 years. In addition, participants completed the Beck Depression Inventory (BDI). Early adversity was determined according to a family adversity index assessed at 3 months of age. Results indicated that individuals homozygous for both the BDNF Val and the 5-HTTLPR L allele showed significantly reduced BDNF levels following exposure to high adversity. In contrast, BDNF levels appeared to be unaffected by early psychosocial adversity in carriers of the BDNF Met or the 5-HTTLPR S allele. While the former group appeared to be most susceptible to depressive symptoms, the impact of early adversity was less pronounced in the latter group. This is the first preliminary evidence indicating that early-life adverse experiences may have lasting sequelae for plasma BDNF levels in humans, highlighting that the susceptibility to this effect is moderated by BDNF Val(66)Met and 5-HTTLPR genotype.
Recent research suggests an important role of FKBP5, a glucocorticoid receptor regulating co-chaperone, in the development of stress-related diseases such as depression and anxiety disorders. The present study aimed to replicate and extend previous evidence indicating that FKBP5 polymorphisms moderate hypothalamus-pituitary-adrenal (HPA) function by examining whether FKBP5 rs1360780 genotype and different measures of childhood adversity interact to predict stress-induced cortisol secretion. At age 19 years, 195 young adults (90 males, 105 females) participating in an epidemiological cohort study completed the Trier Social Stress Test (TSST) to assess cortisol stress responsiveness and were genotyped for the FKBP5 rs1360780. Childhood adversity was assessed using the Childhood Trauma Questionnaire (CTQ) and by a standardized parent interview yielding an index of family adversity. A significant interaction between genotype and childhood adversity on cortisol response to stress was demonstrated for exposure to childhood maltreatment as assessed by retrospective self-report (CTQ), but not for prospectively ascertained objective family adversity. Severity of childhood maltreatment was significantly associated with attenuated cortisol levels among carriers of the rs1360780 CC genotype, while no such effect emerged in carriers of the T allele. These findings point towards the functional involvement of FKBP5 in long-term alterations of neuroendocrine stress regulation related to childhood maltreatment, which have been suggested to represent a premorbid risk or resilience factor in the context of stress-related disorders. (C) 2013 Elsevier B.V. and ECNR This is an open access article under the CC BY-NC-ND license.
There is ample evidence that the early initiation of alcohol use is a risk factor for the development of later alcohol-related problems. The purpose of the current study was to examine whether this association can be explained by indicators of a common underlying susceptibility or whether age at drinking onset may be considered as an independent predictor of later drinking behavior, suggesting a potential causal relationship. Participants were drawn from a prospective cohort study of the long-term outcomes of early risk factors followed up from birth onwards. Structured interviews were administered to 304 participants to assess age at first drink and current drinking behavior. Data on risk factors, including early family adversity, parental alcohol use, childhood psychopathology and stressful life events, were repeatedly collected during childhood using standardized parent interviews. In addition, information on genotype was considered. Results confirmed previous work demonstrating that hazardous alcohol consumption is related to early-adolescent drinking onset. A younger age of first drink was significantly predicted by 5-HTTLPR genotype and the degree of preceding externalizing symptoms, and both factors were related to increased consumption or harmful alcohol use at age 19. However, even after controlling for these potential explanatory factors, earlier age at drinking onset remained a strong predictor of heavy alcohol consumption in young adulthood. The present longitudinal study adds to the current literature indicating that the early onset - adult hazardous drinking association cannot solely be attributed to shared genetic and psychopathologic risk factors as examined in this study.
Epigenetic modulations are a hypothesized link between environmental factors and the development of psychiatric disorders. Research has suggested that patients with depression or bipolar disorder exhibit higher methylation levels in the glucocorticoid receptor gene NR3C1. We aimed to investigate whether NR3C1 methylation changes are similarly associated with externalizing disorders such as aggressive behavior and conduct disorder. NR3C1 exon 1F methylation was analyzed in young adults with a lifetime diagnosis of an externalizing disorder (N = 68) or a depressive disorder (N = 27) and healthy controls (N = 124) from the Mannheim Study of Children at Risk. The externalizing disorders group had significantly lower NR3C1 methylation levels than the lifetime depressive disorder group (p = 0.009) and healthy controls (p = 0.001) This report of lower methylation levels in NR3C1 in externalizing disorders may indicate a mechanism through which the differential development of externalizing disorders as opposed to depressive disorders might occur.
Findings on the etiology of aggressive behavior have provided evidence for an effect both of genetic factors, such as variation in the monoamine oxidase A (MAOA) gene, and adverse environmental factors. Recent studies have supported the existence of gene × environment interactions, with early experiences playing a key role. In the present study, the effects of prenatal nicotine exposure, MAOA genotype and their interaction on aggressive behavior during young adulthood were examined. In a sample of 272 young adults (129 males, 143 females) from an epidemiological cohort study, smoking during pregnancy was measured with a standardized parent interview at the offspring’s age of 3 months. Aggressive behavior was assessed between the ages of 19 and 25 years using the Young Adult Self-Report. DNA was genotyped for the MAOA 5′ untranslated region variable number of tandem repeats polymorphism (VNTR). Results revealed a significant interaction between MAOA and smoking during pregnancy, indicating higher levels of aggressive behavior in young adults carrying the MAOA low-expressing genotype who had experienced prenatal nicotine exposure (n = 8, p = .025). In contrast, in carriers of the MAOA high-expressing genotype, maternal smoking during pregnancy had no effect on aggressive behavior during young adulthood (n = 20, p = .145). This study extends earlier findings demonstrating an interaction between MAOA genotype and prenatal nicotine exposure on aggressive behavior into young adulthood. The results point to the long-term adverse effects of smoking during pregnancy on the offspring’s mental health, possibly underlining the importance of smoking cessation during pregnancy. According to the nature of the study (particularly sample size and power), analyses are exploratory and results need to be interpreted cautiously.
Converging evidence emphasizes the role of an interaction between monoamine oxidase A (MAOA) genotype, environmental adversity, and sex in the pathophysiology of aggression. The present study aimed to clarify the impact of this interaction on neural activity in aggression-related brain systems. Functional magnetic resonance imaging was performed in 125 healthy adults from a high-risk community sample followed since birth. DNA was genotyped for the MAOA-VNTR (variable number of tandem repeats). Exposure to childhood life stress (CLS) between the ages of 4 and 11 years was assessed using a standardized parent interview, aggression by the Youth/Young Adult Self-Report between the ages of 15 and 25 years, and the VIRA-R (Vragenlijst Instrumentele En Reactieve Agressie) at the age of 15 years. Significant interactions were obtained between MAOA genotype, CLS, and sex relating to amygdala, hippocampus, and anterior cingulate cortex (ACC) response, respectively. Activity in the amygdala and hippocampus during emotional face-matching increased with the level of CLS in male MAOA-L, while decreasing in male MAOA-H, with the reverse pattern present in females. Findings in the opposite direction in the ACC during a flanker NoGo task suggested that increased emotional activity coincided with decreased inhibitory control. Moreover, increasing amygdala activity was associated with higher Y(A)SR aggression in male MAOA-L and female MAOA-H carriers. Likewise, a significant association between amygdala activity and reactive aggression was detected in female MAOA-H carriers. The results point to a moderating role of sex in the MAOAx CLS interaction for intermediate phenotypes of emotional and inhibitory processing, suggesting a possible mechanism in conferring susceptibility to violence-related disorders.
Background: Recently, first evidence has been reported for a geneparenting interaction (G x E) with regard to adolescent alcohol use. The present investigation set out to extend this research using the catechol-O-methyltransferase (COMT) Val158Met polymorphism as a genetic susceptibility factor. Moreover, the current study examined whether a potential G x E would be consistent with one of two models of geneenvironment interplay (genetic vulnerability vs. differential susceptibility). Methods: Data were collected as part of an ongoing epidemiological cohort study following the outcome of early risk factors from birth into adulthood. Two hundred and eighty-five participants (130 males, 155 females) were genotyped for the COMT Val(158) Met polymorphism and were administered an alcohol interview, providing measures of current frequency and amount of drinking at ages 15 and 19 years. Information on three dimensions of perceived parenting behavior was obtained from the 15-year-olds. Results: Adolescents homozygous for the Met allele showed higher drinking activity at age 19 years when their parents had engaged in less supervision or were less involved, while their drinking activity was reduced under conditions of favorable parenting. No such relationship was found in individuals carrying the Val allele. Conclusions: The present findings correspond with the pattern of results predicted by the differential susceptibility hypothesis, suggesting that environmental variation would have a greater impact in individuals carrying a genetic susceptibility such that, in this group, exposure to negative environmental conditions would result in more adverse outcomes and the experience of favorable conditions would lead to more positive outcomes.
Context: Recent evidence suggests that gene X environment interactions could explain the inconsistent findings of association studies relating the dopamine transporter (DAT1) gene with attention-deficit/hyperactivity disorder (ADHD). 1bjective: To examine whether psychosocial adversity moderated the effect of genetic variation in DAT1 on ADHD symptoms in. adolescents from a high-risk community sample. Design: Prospective cohort study. Setting: Data were taken from the Mannheim Study of Children at Risk, an ongoing longitudinal study of the long-term outcomes of early risk factors followed up from birth on. Participants: Three hundred five adolescents (146 boys, 159 girls) participated in a follow-up assessment at age 15 years. Main Outcome Measures: Measures of ADHD symptoms according to DSM-IV were obtained using standardized structural interviews with adolescents and their parents. Psychosocial adversity was determined according to an "enriched" family adversity index as proposed by Rutter and Quinton. DNA was genotyped for the common DAT1 40-base pair (bp) variable number of tandem repeats (VNTR) polymorphism in the 3' untranslated region; 3 previously described single nucleotide polymorphisms in exon 15, intron 9, and exon 9; and a novel 30-bp VNTR polymorphism in intron 8. Results: Adolescents homozygous for the 10-repeat allele of the 40-bp VNTR polymorphism who grew up in greater psychosocial adversity exhibited significantly more inattention and hyperactivity-impulsivity than adolescents with other genotypes or who lived in less adverse family conditions (significant interaction, P=.013-017). This gene X environment interaction was also observed in individuals homozygous for the 6-repeat allele of the 30-bp VNTR polymorphism and the haplotype comprising both markers. Conclusions: These findings provide initial evidence that environmental risks as described by the Rutter Family Adversity Index moderate the impact of the DAT1 gene on ADHD symptoms, suggesting a DAT1 effect only in those individuals exposed to psychosocial adversity.
Previous research examining gene-environment interaction (G x E) with regard to vulnerability to depression and anxiety has yielded conflicting results. The present study was designed to further investigate G x F between 5-HTTLPR and exposure to environmental adversity, using different phenotypic and genotypic characterizations as well as different types of adversity within a prospective study design. Data were available from an ongoing epidemiological cohort Study following the outcome of early risk factors from birth to adulthood. At age 19 yr, 309 participants (142 males, 167 females) were characterized on measures of depression and anxiety through interview and questionnaire (DSM-IV diagnosis, Beck Depression Inventory, Harm Avoidance). Environmental adversity was assessed at birth (family adversity), and at age 19 yr (stressful life events). Bi- and tri-allelic 5-HTTLPR genotypes were obtained from genomic DNA. Results indicated that depression and anxiety in 19-yr-olds were strongly associated with both family adversity and stressful life events. Individuals with the LL genotype of 5-HTTLPR who were exposed to high family adversity displayed significantly higher rates of depressive or anxiety disorders and had more depressive symptoms than those without either condition. This G x E replicates recent findings from an epidemiological cohort study of adolescents but is in contrast to many previous reports suggesting an interaction with the S allele. No evidence for G x E was obtained with regard to current stressful life events and trait anxiety. One possible source for the conflicting findings might be attributed to heterogeneity in depression phenotypes and environmental adversity.
Accumulating research suggests a moderating role for the corticotropin-releasing hormone receptor 1 gene (CRHR1) in the association between childhood adversity and adult depression. The present study aims to replicate recent findings using different genetic variants and measures of early adversity assessed both prospectively and retrospectively. Data were collected in the context of an ongoing epidemiological cohort study following the outcome of early risk factors from birth into adulthood. 300 participants (137 males, 163 females) were genotyped for four CRHR1 SNPs (rs7209436, rs110402, rs242924, and rs17689882) and completed the Beck Depression Inventory at ages 19, 22 and 23 years. Childhood adversity was assessed using the Childhood Trauma Questionnaire and by a standardized parent interview yielding an index of family adversity. Our results indicate that CRHR1 and childhood adversity interacted to predict depressive symptoms in young adults. Specifically, we found that the impact of childhood maltreatment on adult depressive symptoms was significantly higher in individuals (i) with two copies of the CRHR1 TAT haplotype, and (ii) homozygous for the G allele of rs17689882. The interaction was demonstrated for exposure to childhood maltreatment as assessed by retrospective self-report, but not to prospectively ascertain objective family adversity. The present study partially replicates recent findings of a CRHR1 by childhood adversity interaction with regard to adult depression highlighting the subjective characteristics of the environmental pathogen that is operative in this interaction.
Background: Evidence from animal studies supports a role for serotonin transporter gene promoter polymorphism (5-HTTLPR) gene-environment interaction (G X E) in the development of excessive alcohol intake. Few studies in humans have been conducted on this topic, yielding inconsistent results. The present study aims to further explore G x E between 5-HTTLPR and exposure to psychosocial adversity on alcohol consumption in a high-risk community sample of young adults. Methods: Data were collected as part of the Mannheim Study of Children at Risk, an ongoing epidemiological cohort study following the outcome of early risk factors from birth into young adulthood. At age 19 years, 309 participants (142 male participants, 167 female participants) were genotyped for the biallelic and triallelic 5-HTTLPR and were administered a 45-day alcohol timeline follow-back interview, providing measures of the total number of drinks and the number of binge drinking days. Psychosocial adversity was assessed at birth (family adversity) and at age 19 (negative life events). Results: In contrast to various previous reports, a significant G x E emerged, indicating that, when exposed to high psychosocial adversity, individuals with the LL genotype of 5-HTTLPR exhibited more hazardous drinking than those carrying the S allele or those without exposure to adversity. This effect, which was confined to male participants, held both for different classifications of 5-HTTLPR and different types of adversity. Conclusions: One explanation for the discrepant results might be heterogeneity in alcohol phenotypes. While the L allele relates more strongly to early-onset alcoholism, the S allele may be linked more closely to alcohol use associated with anxiety and depression.
Recent evidence suggests that heterogeneity in the age at onset could explain the inconsistent findings of association studies relating the dopamine transporter (DAT1) gene with alcohol and nicotine consumption. The aim of this study was to examine interactions between two DAT1 polymorphisms and different initiation ages with regard to alcohol and tobacco consumption levels and dependence. Two hundred and ninety-one young adults (135 males, 156 females) participating in the Mannheim Study of Children at Risk were genotyped for the 40-bp variable number of tandem repeats (VNTR) and rs27072 polymorphisms of DAT1. Age at initiation was assessed at age 15 and 19 years. Information about current alcohol and tobacco consumption was obtained at age 19 years using self-report measures and structured interviews. Results suggest that age at onset of intensive consumption moderated the association of the DAT1 gene with early adult substance use and dependence, revealing a DAT1 effect only among individuals homozygous for the 10r allele of the 40-bp VNTR who had started daily smoking or being intoxicated early in life. Equally, carriers of the T allele of the rs27072 polymorphism reporting an early age at first intoxication showed higher current alcohol consumption at age 19 years. In contrast, no interaction between rs27072 and the age at first cigarette with regard to later smoking was observed. These findings provide evidence that the DAT1 gene interacts with an early heavy or regular drug exposure of the maturing adolescent brain to predict substance (ab)use in young adulthood. Further studies are required to confirm these findings.
Interindividual variability in the regulation of the human stress system accounts for a part of the individual's liability to stress-related diseases. These differences are influenced by environmental and genetic factors. Early childhood adversity is a well-studied environmental factor affecting an individual's stress response which has been shown to be modulated by gene environment interaction (GxE). Neuropeptide Y (NPY) plays a role in stress regulation and genetic variation in NPY may influence stress responses. In this study, we analyzed the association of a common variant in the NPY gene promoter, rs16147, with cortisol and ACTH responses to acute psychosocial stress in young adults from the Mannheim Study of Children at Risk (MARS), an ongoing epidemiological cohort study following the outcome of early adversity from birth into adulthood. We found evidence of a GxE interaction between rs16147 and early adversity significantly affecting HPA axis responses to acute psychosocial stress. These findings suggest that the neurobiological mechanisms linking early adverse experience and later neuroendocrine stress regulation are modulated by a gene variant whose functional relevance is documented by increasing convergent evidence from in vitro, animal and human studies.