The Long-Term Impact of Early Life Stress on Orbitofrontal Cortical Thickness.

Early adversity has been related to brain structure alterations and to an increased risk of psychiatric disorders. The orbitofrontal cortex (OFC) is a key region for emotional processing, with structural alterations being described in several mental disorders. However, little is known about how its cortical thickness (CT) is affected by the long-term impact of life stress (LS) at different developmental stages. The present study aimed to investigate the effect of LS during infancy, childhood, and adolescence on CT alterations in the OFC and on psychopathology in 190 adults of an ongoing prospective cohort study. Chronic stressful life events were assessed in regular intervals. Participants rated depressive symptoms at the ages of 22 and 23 years. Morphometric data were collected at the participants' age of 25 years. Chronic LS during infancy was associated with reduced CT in the right OFC and increased depressive symptoms. Moreover, the impact of chronic LS during infancy on OFC thickness was partially mediated by depressive symptoms in adulthood, suggesting an interplay of early LS, psychopathology, and CT alterations. Our findings highlight the long-term impact of early LS on an affective core brain structure and psychopathology later in life.

Impact on birth weight of maternal smoking throughout pregnancy mediated by DNA methylation.

BACKGROUND: Cigarette smoking has severe adverse health consequences in adults and in the offspring of mothers who smoke during pregnancy. One of the most widely reported effects of smoking during pregnancy is reduced birth weight which is in turn associated with chronic disease in adulthood. Epigenome-wide association studies have revealed that smokers show a characteristic "smoking methylation pattern", and recent authors have proposed that DNA methylation mediates the impact of maternal smoking on birth weight. The aims of the present study were to replicate previous reports that methylation mediates the effect of maternal smoking on birth weight, and for the first time to investigate whether the observed mediation effects are sex-specific in order to account for known sex-specific differences in methylation levels. METHODS: Methylation levels in the cord blood of 313 newborns were determined using the Illumina HumanMethylation450K Beadchip. A total of 5,527 CpG sites selected on the basis of evidence from the literature were tested. To determine whether the observed association between maternal smoking and birth weight was attributable to methylation, mediation analyses were performed for significant CpG sites. Separate analyses were then performed in males and females. RESULTS: Following quality control, 282 newborns eventually remained in the analysis. A total of 25 mothers had smoked consistently throughout the pregnancy. The birthweigt of newborns whose mothers had smoked throughout pregnancy was reduced by >200g. After correction for multiple testing, 30 CpGs showed differential methylation in the maternal smoking subgroup including top "smoking methylation pattern" genes AHRR, MYO1G, GFI1, CYP1A1, and CNTNAP2. The effect of maternal smoking on birth weight was partly mediated by the methylation of cg25325512 (PIM1); cg25949550 (CNTNAP2); and cg08699196 (ITGB7). Sex-specific analyses revealed a mediating effect for cg25949550 (CNTNAP2) in male newborns. CONCLUSION: The present data replicate previous findings that methylation can mediate the effect of maternal smoking on birth weight. The analysis of sex-dependent mediation effects suggests that the sex of the newborn may have an influence. Larger studies are warranted to investigate the role of both the identified differentially methylated loci and the sex of the newborn in mediating the association between maternal smoking during pregnancy and birth weight.

Sex-specific trajectories of ADHD symptoms from adolescence to young adulthood.

Reports of current ADHD symptoms in adults with a childhood diagnosis of ADHD are often discrepant: While one subgroup reports a particularly high level of current ADHD symptoms, another reports-in contrast-a very low level. The reasons for this difference remain unclear. Although sex might play a moderating role, it has not yet been examined in this regard. In an epidemiological cohort study from birth to young adulthood, childhood ADHD diagnoses were assessed at the ages of 4.5, 8, and 11 years based on parent ratings. Sex-specific development of ADHD symptoms was analyzed from the age of 15 to 25 years via self-reported ADHD symptoms in participants with (n = 47) and without childhood ADHD (n = 289) using a random coefficient regression model. The congruence between parent reports and adolescents' self-ratings was examined, and the role of childhood ADHD diagnosis, childhood OCC/CD, and childhood internalizing disorder as possible sex-specific predictors of self-reported ADHD symptoms at age 25 years was investigated. With regard to self-reported ADHD symptoms, females with a childhood ADHD diagnosis reported significantly more ADHD symptoms compared to females without childhood ADHD and males with and without ADHD throughout adolescence and young adulthood. In contrast, males with childhood ADHD did not differ from control males either at age 15 or at age 25 years. Only in females did a childhood diagnosis of an externalizing disorder (ADHD and CD/ODD) predict self-reported ADHD symptoms by age 25 years. Our findings suggest that self-reports of young adults with a childhood diagnosis of ADHD are influenced by sex. Specifically, females with childhood ADHD report increased levels of ADHD symptoms upon reaching adulthood. To correctly evaluate symptoms and impairment in this subgroup, other, more objective, sources of information may be advisable, such as neurophysiological measures.

Child regulative temperament as a mediator of parenting in the development of depressive symptoms: a longitudinal study from early childhood to preadolescence.

Child temperament as well as parenting behaviors have been linked to adolescent depression. Beyond their main effects, the interplay between these factors is of interest. For example, in an interactive model, a differential susceptibility of temperamental variants to parenting has been suggested. However, so far, the differential susceptibility hypothesis has mostly been studied with a focus on externalizing disorders. On the other hand, parenting may shape the child's temperament and vice versa in a transactional process. In a prospective, longitudinal at-risk sample (163 boys, 176 girls), we assessed emotional (easy-difficult) and regulative (self-control) temperament at ages 4.5, and 8 years, respectively, as well as parenting quality at age 4.5 years using the HOME inventory. Hierarchical linear regression analysis was used to investigate the prediction of depressive symptoms at age 11, measured by the Child Depression Inventory, including interaction terms between the temperament variable and parenting. We additionally tested whether parenting was mediated by child temperament. As previously reported, both self-control and parenting were longitudinally associated with preadolescent depressive symptoms. There were no interactive effects between temperament and parenting. However, the effects of parenting were partly mediated by self-control. Our data do not support a differential susceptibility of temperamental variants in the development of preadolescent depression. However, our results are in line with the assumption that parenting may shape young children's temperament, with positive parenting in the early childhood fostering the development of regulative temperament.

Impact of prenatal stress on the dyadic behavior of mothers and their 6-month-old infants during a play situation: role of different dimensions of stress.

Prenatal stress (PS) is an established risk factor in the etiology of mental disorders. Although mother-child interaction is the infant's first important training in dealing with stress, little is yet known about the impact of PS on mother-infant dyadic behavior. The current study aimed to elucidate the prospective influence of psychological and physiological stresses during pregnancy on mother-infant dyadic behavior. Mother-infant interactions were videotaped at 6-month postpartum and coded into three dyadic patterns: (1) both positive; (2) infant protesting-mother positive; and (3) infant protesting-mother negative, using the infant and caregiver engagement phases. Exposure to PS was assessed during pregnancy using psychological (i.e., psychopathological, perceived, and psychosocial PS; n = 164) and physiological stress measures (i.e., maternal cortisol; n = 134). Group comparisons showed that psychosocial PS was predictive of mother-infant behavior at 6-month postpartum, indicating that dyads of prenatally high-stressed mothers exhibited significantly more positive interaction patterns (i.e., infant positive-mother positive) as compared to the prenatally low-stressed group. Physiological PS was unrelated to mother-infant behavior. These results suggest that mild psychosocial PS may be advantageous for positive mother-infant dyadic behavior, which is in accordance with the stress-inoculation model that assumes a beneficial effect of PS.

Evidence for a Sex-Dependent MAOA× Childhood Stress Interaction in the Neural Circuitry of Aggression.

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 MAOA× CLS interaction for intermediate phenotypes of emotional and inhibitory processing, suggesting a possible mechanism in conferring susceptibility to violence-related disorders.

Association between pubertal stage at first drink and neural reward processing in early adulthood.

Puberty is a critical time period during human development. It is characterized by high levels of risk-taking behavior, such as increased alcohol consumption, and is accompanied by various neurobiological changes. Recent studies in animals and humans have revealed that the pubertal stage at first drink (PSFD) significantly impacts drinking behavior in adulthood. Moreover, neuronal alterations of the dopaminergic reward system have been associated with alcohol abuse or addiction. This study aimed to clarify the impact of PSFD on neuronal characteristics of reward processing linked to alcohol-related problems. One hundred sixty-eight healthy young adults from a prospective study covering 25 years participated in a monetary incentive delay task measured with simultaneous EEG-fMRI. PSFD was determined according to the age at menarche or Tanner stage of pubertal development, respectively. Alcohol-related problems in early adulthood were assessed with the Alcohol Use Disorder Identification Test (AUDIT). During reward anticipation, decreased fMRI activation of the frontal cortex and increased preparatory EEG activity (contingent negative variation) occurred with pubertal compared to postpubertal first alcohol intake. Moreover, alcohol-related problems during early adulthood were increased in pubertal compared to postpubertal beginners, which was mediated by neuronal activation of the right medial frontal gyrus. At reward delivery, increased fMRI activation of the left caudate and higher feedback-related EEG negativity were detected in pubertal compared to postpubertal beginners. Together with animal findings, these results implicate PSFD as a potential modulator of psychopathology, involving altered reward anticipation. Both PSFD timing and reward processing might thus be potential targets for early prevention and intervention.

Interaction between COMT Val(158)Met polymorphism and childhood adversity affects reward processing in adulthood.

BACKGROUND: Accumulating evidence suggests that altered dopamine transmission may increase the risk of mental disorders such as ADHD, schizophrenia or depression, possibly mediated by reward system dysfunction. This study aimed to clarify the impact of the COMT Val(158)Met polymorphism in interaction with environmental variation (G×E) on neuronal activity during reward processing. METHODS: 168 healthy young adults from a prospective study conducted over 25years participated in a monetary incentive delay task measured with simultaneous EEG-fMRI. DNA was genotyped for COMT, and childhood family adversity (CFA) up to age 11 was assessed by a standardized parent interview. RESULTS: At reward delivery, a G×E revealed that fMRI activation for win vs. no-win trials in reward-related regions increased with the level of CFA in Met homozygotes as compared to Val/Met heterozygotes and Val homozygotes, who showed no significant effect. During the anticipation of monetary vs. verbal rewards, activation decreased with the level of CFA, which was also observed for EEG, in which the CNV declined with the level of CFA. CONCLUSIONS: These results identify convergent genetic and environmental effects on reward processing in a prospective study. Moreover, G×E effects during reward delivery suggest that stress during childhood is associated with higher reward sensitivity and reduced efficiency in processing rewarding stimuli in genetically at-risk individuals. Together with previous evidence, these results begin to define a specific system mediating interacting effects of early environmental and genetic risk factors, which may be targeted by early intervention and prevention.

Interacting effect of MAOA genotype and maternal prenatal smoking on aggressive behavior in young adulthood.

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.

Alterations of Glucocorticoid Receptor Gene Methylation in Externalizing Disorders During Childhood and Adolescence.

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.

Frequency-specific coupling between trial-to-trial fluctuations of neural responses and response-time variability.

We assessed intra-individual variability of response times (RT) and single-trial P3 amplitudes following targets in healthy adults during a Flanker/NO-GO task. RT variability and variability of the neural responses coupled at the faster frequencies examined (0.07-0.17 Hz) at Pz, the target-P3 maxima, despite non-significant associations for overall variability (standard deviation, SD). Frequency-specific patterns of variability in the single-trial P3 may help to understand the neurophysiology of RT variability and its explanatory models of attention allocation deficits beyond intra-individual variability summary indices such as SD.

Role of CNR1 polymorphisms in moderating the effects of psychosocial adversity on impulsivity in adolescents.

Enhanced endocannabinoid signaling has been implicated in typically adolescent behavioral features such as increased risk-taking, impulsivity and novelty seeking. Research investigating the impact of genetic variants in the cannabinoid receptor 1 gene (CNR1) and of early rearing conditions has demonstrated that both factors contribute to the prediction of impulsivity-related phenotypes. The present study aimed to test the hypothesis of an interaction of the two most studied CNR1 polymorphisms rs806379 and rs1049353 with early psychosocial adversity in terms of affecting impulsivity in 15-year-olds from an epidemiological cohort sample followed since birth. In 323 adolescents (170 girls, 153 boys), problems of impulse control and novelty seeking were assessed using parent-report and self-report, respectively. Exposure to early psychosocial adversity was determined in a parent interview conducted at the age of 3 months. The results indicated that impulsivity increased following exposure to early psychosocial adversity, with this increase being dependent on CNR1 genotype. In contrast, while individuals exposed to early adversity scored higher on novelty seeking, no significant impact of genotype or the interaction thereof was detected. This is the first evidence to suggest that the interaction of CNR1 gene variants with the experience of early life adversity may play a role in determining adolescent impulsive behavior. However, given that the reported findings are obtained in a high-risk community sample, results are restricted in terms of interpretation and generalization. Future research is needed to replicate these findings and to identify the mediating mechanisms underlying this effect.

Simultaneous EEG and fMRI reveals a causally connected subcortical-cortical network during reward anticipation.

Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) have been used to study the neural correlates of reward anticipation, but the interrelation of EEG and fMRI measures remains unknown. The goal of the present study was to investigate this relationship in response to a well established reward anticipation paradigm using simultaneous EEG-fMRI recording in healthy human subjects. Analysis of causal interactions between the thalamus (THAL), ventral-striatum (VS), and supplementary motor area (SMA), using both mediator analysis and dynamic causal modeling, revealed that (1) THAL fMRI blood oxygenation level-dependent (BOLD) activity is mediating intermodal correlations between the EEG contingent negative variation (CNV) signal and the fMRI BOLD signal in SMA and VS, (2) the underlying causal connectivity network consists of top-down regulation from SMA to VS and SMA to THAL along with an excitatory information flow through a THAL→VS→SMA route during reward anticipation, and (3) the EEG CNV signal is best predicted by a combination of THAL fMRI BOLD response and strength of top-down regulation from SMA to VS and SMA to THAL. Collectively, these findings represent a likely neurobiological mechanism mapping a primarily subcortical process, i.e., reward anticipation, onto a cortical signature.

Sequential inhibitory control processes assessed through simultaneous EEG-fMRI.

Inhibitory response control has been extensively investigated in both electrophysiological (ERP) and hemodynamic (fMRI) studies. However, very few multimodal results address the coupling of these inhibition markers. In fMRI, response inhibition has been most consistently linked to activation of the anterior insula and inferior frontal cortex (IFC), often also the anterior cingulate cortex (ACC). ERP work has established increased N2 and P3 amplitudes during NoGo compared to Go conditions in most studies. Previous simultaneous EEG-fMRI imaging reported association of the N2/P3 complex with activation of areas like the anterior midcingulate cortex (aMCC) and anterior insula. In this study we investigated inhibitory control in 23 healthy young adults (mean age=24.7, n=17 for EEG during fMRI) using a combined Flanker/NoGo task during simultaneous EEG and fMRI recording. Separate fMRI and ERP analysis yielded higher activation in the anterior insula, IFG and ACC as well as increased N2 and P3 amplitudes during NoGo trials in accordance with the literature. Combined analysis modelling sequential N2 and P3 effects through joint parametric modulation revealed correlation of higher N2 amplitude with deactivation in parts of the default mode network (DMN) and the cingulate motor area (CMA) as well as correlation of higher central P3 amplitude with activation of the left anterior insula, IFG and posterior cingulate. The EEG-fMRI results resolve the localizations of these sequential activations. They suggest a general role for allocation of attentional resources and motor inhibition for N2 and link memory recollection and internal reflection to P3 amplitude, in addition to previously described response inhibition as reflected by the anterior insula.

Intrauterine exposure to cigarette smoke is associated with increased ghrelin concentrations in adulthood.

BACKGROUND: The appetite-stimulating hormone ghrelin is a fundamental regulator of human energy metabolism. A series of studies support the notion that long-term appetite and weight regulation may be already programmed in early life and it could be demonstrated that the intrauterine environment affects the ghrelin system of the offspring. Animal studies have also shown that intrauterine programming of orexigenic systems persists even until adolescence/adulthood. METHODS: We hypothesized that plasma ghrelin concentrations in adulthood may be associated with the intrauterine exposure to cigarette smoke. We examined this hypothesis in a sample of 19-year-olds followed up since birth in the framework of the Mannheim Study of Children at Risk, an ongoing epidemiological cohort study of the long-term outcome of early risk factors. RESULTS: As a main finding, we found that ghrelin plasma concentrations in young adults who had been exposed to cigarette smoke in utero were significantly higher than in those without prenatal smoke exposure. Moreover, individuals with intrauterine nicotine exposure showed a significantly higher prevalence of own smoking habits and lower educational status compared to those in the group without exposure. CONCLUSION: Smoking during pregnancy may be considered as an adverse intrauterine influence that may alter the endocrine-metabolic status of the offspring even until early adulthood.

Mothers' prenatal stress and their children's antisocial outcomes--a moderating role for the dopamine D4 receptor (DRD4) gene.

BACKGROUND: Maternal distress during pregnancy has been linked to aggressive behavior in offspring. This effect has been interpreted in terms of 'fetal programming'. The 7-repeat (7r) allele of a VNTR polymorphism in exon III of the human dopamine receptor D4 (DRD4) has consistently been associated with externalizing behavior problems, especially in the presence of adverse environmental factors. So far, it is not known whether the DRD4 genotype moderates the effect of prenatal maternal stress on the development of childhood antisocial behavior. METHODS: As part of an ongoing epidemiological cohort study, prenatal maternal stress was assessed using self-report 3 months following child birth. When children were 8, 11, and 15 years old, mothers rated their children's externalizing behavior, and diagnoses of conduct disorder and/or oppositional defiant disorder (CD/ODD) according to DSM-IV were obtained. In a sample of N = 308 participants, the effects of the DRD4 genotype, prenatal maternal stress, and the interaction thereof on antisocial outcome were tested. RESULTS: Under conditions of elevated prenatal maternal stress, children carrying one or two DRD4 7r alleles were at increased risk of a diagnosis of CD/ODD. Moreover, homozygous carriers of the DRD4 7r allele displayed more externalizing behavior following exposure to higher levels of prenatal maternal stress, while homozygous carriers of the DRD4 4r allele turned out to be insensitive to the effects of prenatal stress. CONCLUSIONS: This study is the first to report a gene-environment interaction related to DRD4 and prenatal maternal stress using data from a prospective study, which extends earlier findings on the impact of prenatal maternal stress with respect to childhood antisocial behavior.

Maternal stimulation in infancy predicts hypothalamic-pituitary-adrenal axis reactivity in young men.

Evidence from animal research has demonstrated the effect of early maternal care on the offspring's endocrine and behavioral stress response in adulthood. The present prospective study investigates, in humans, the long-term impact of maternal responsiveness and stimulation during early mother-child interaction on adrenocorticotropic hormone (ACTH) and cortisol response to a psychosocial laboratory stressor in adulthood. The data are from an epidemiological cohort study of the long-term outcome of early risk factors assessed at birth. At age 3 months, mothers and infants were videotaped during a 10-min standardized nursing and playing situation and evaluated by trained raters for maternal stimulation and infant and maternal responsiveness. At age 19 years, 270 participants (146 females, 124 males) completed the Trier Social Stress Test. The results indicated that less maternal stimulation during early interaction at age 3 months predicted diminished plasma ACTH and cortisol increase in response to acute psychosocial stress in male, but not female offspring. In contrast, maternal responsiveness was found to be unrelated to hypothalamic-pituitary-adrenal (HPA) reactivity. In accordance with the findings from animal research, the present study provides prospective evidence in humans of a long-term association between early maternal interaction behavior and the offspring's hormonal stress response in young adulthood, suggesting that poor maternal stimulation in early infancy may result in reduced HPA axis reactivity to an acute psychosocial stressor in males.

Impact of pubertal stage at first drink on adult drinking behavior.

BACKGROUND: Early alcohol use is one of the strongest predictors of later alcohol use disorders, with early use usually taking place during puberty. Many researchers have suggested drinking during puberty as a potential biological basis of the age at first drink (AFD) effect. However, the influence of the pubertal phase at alcohol use initiation on subsequent drinking in later life has not been examined so far. METHODS: Pubertal stage at first drink (PSFD) was determined in N = 283 young adults (131 males, 152 females) from an epidemiological cohort study. At ages 19, 22, and 23 years, drinking behavior (number of drinking days, amount of alcohol consumed, hazardous drinking) was assessed using interview and questionnaire methods. Additionally, an animal study examined the effects of pubertal or adult ethanol (EtOH) exposure on voluntary EtOH consumption in later life in 20 male Wistar rats. RESULTS: PSFD predicted drinking behavior in humans in early adulthood, indicating that individuals who had their first drink during puberty displayed elevated drinking levels compared to those with postpubertal drinking onset. These findings were corroborated by the animal study, in which rats that received free access to alcohol during the pubertal period were found to consume more alcohol as adults, compared to the control animals that first came into contact with alcohol during adulthood. CONCLUSIONS: The results point to a significant role of stage of pubertal development at first contact with alcohol for the development of later drinking habits. Possible biological mechanisms and implications for prevention are discussed.

Early smoking onset may promise initial pleasurable sensations and later addiction.

There is converging evidence suggesting a particular susceptibility to the addictive properties of nicotine among adolescents. The aim of the current study was to prospectively ascertain the relationship between age at first cigarette and initial smoking experiences, and to examine the combined effects of these characteristics of adolescent smoking behavior on adult smoking. It was hypothesized that the association between earlier age at first cigarette and later development of nicotine dependence may, at least in part, be attributable to differences in experiencing pleasurable early smoking sensations. Data were drawn from the participants of the Mannheim Study of Children at Risk, an ongoing epidemiological cohort study from birth to adulthood. Structured interviews at age 15, 19 and 22 years were conducted to assess the age at first cigarette, early smoking experiences and current smoking behavior in 213 young adults. In addition, the participants completed the Fagerström Test for Nicotine Dependence. Adolescents who smoked their first cigarette at an earlier age reported more pleasurable sensations from the cigarette, and they were more likely to be regular smokers at age 22. The age at first cigarette also predicted the number of cigarettes smoked and dependence at age 22. Thus, both the age of first cigarette and the pleasure experienced from the cigarette independently predicted aspects of smoking at age 22.

Catechol-O-methyltransferase Val158 Met genotype, parenting practices and adolescent alcohol use: testing the differential susceptibility hypothesis.

BACKGROUND: Recently, first evidence has been reported for a gene-parenting interaction (G × E) with regard to adolescent alcohol use. The present investigation set out to extend this research using the catechol-O-methyltransferase (COMT) Val(158) Met polymorphism as a genetic susceptibility factor. Moreover, the current study examined whether a potential G×E would be consistent with one of two models of gene-environment 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.