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Background: Dopamine plays an important role in orienting and the regulation of selective attention to relevant stimulus characteristics. Thus, we examined the influences of functional variants related to dopamine inactivation in the dopamine transporter (DAT1) and catechol-O-methyltransferase genes (COMT) on the time-course of visual processing in a contingent negative variation (CNV) task.
Methods: 64-channel EEG recordings were obtained from 195 healthy adolescents of a community-based sample during a continuous performance task (A-X version). Early and late CNV as well as preceding visual evoked potential components were assessed.
Results: Significant additive main effects of DAT1 and COMT on the occipito-temporal early CNV were observed. In addition, there was a trend towards an interaction between the two polymorphisms. Source analysis showed early CNV generators in the ventral visual stream and in frontal regions. There was a strong negative correlation between occipito-temporal visual post-processing and the frontal early CNV component. The early CNV time interval 500-1000 ms after the visual cue was specifically affected while the preceding visual perception stages were not influenced.
Conclusions: Late visual potentials allow the genomic imaging of dopamine inactivation effects on visual post-processing. The same specific time-interval has been found to be affected by DAT1 and COMT during motor post-processing but not motor preparation. We propose the hypothesis that similar dopaminergic mechanisms modulate working memory encoding in both the visual and motor and perhaps other systems.
Objective: To investigate the association of the neuropeptide Y (NPY) promoter polymorphism rs16147 with body mass index (BMI) during the course of development from infancy to adulthood.
Design: Longitudinal, prospective study of a German community sample.
Subjects: n = 306 young adults (139 males, 167 females).
Measurements: Participants' body weight and height were assessed at the ages of 3 months and 2, 4.5, 8, 11, 15 and 19 years. NPY rs16147 was genotyped.
Results: Controlling for a number of possible confounders, homozygote carriers of the rs16147 C allele exhibited significantly lower BMI scores when compared with individuals carrying the T allele. In addition, a significant genotype by age interaction emerged, indicating that the genotype effect increased during the course of development.
Conclusions: This is the first longitudinal study to report an association between rs16147 and BMI during childhood and adolescence. The finding that this effect increased during the course of development may either be due to age-dependent alterations in gene expression or to maturation processes within the weight regulation circuits of the central nervous system.
Background:
Recent evidence from animal experiments and studies in humans suggests that early age at first drink (AFD) may lead to higher stress-induced drinking. The present study aimed to extend these findings by examining whether AFD interacted with stressful life events (SLE) and/or with daily hassles regarding the impact on drinking patterns among young adults.
Method:
In 306 participants of an epidemiological cohort study, AFD was assessed together with SLE during the past 3 years, daily hassles in the last month, and drinking behavior at age 22. As outcome variables, 2 variables were derived, reflecting different aspects of alcohol use: the amount of alcohol consumed in the last month and the drinking frequency, indicated by the number of drinking days in the last month.
Results:
Linear regression models revealed an interaction effect between the continuous measures of AFD and SLE on the amount of alcohol consumed. The earlier young adults had their first alcoholic drink and the higher the levels of SLE they were exposed to, the disproportionately more alcohol they consumed. Drinking frequency was not affected by an interaction of these variables, while daily hassles and their interaction with AFD were unrelated to drinking behavior.
Conclusions:
These findings highlight the importance of early age at drinking onset as a risk factor for later heavy drinking under high load of SLE. Prevention programs should aim to raise age at first contact with alcohol. Additionally, support in stressful life situations and the acquisition of effective coping strategies might prevent heavy drinking in those with earlier drinking onset.
Objective: The delineation of developmental pathways to juvenile depressive symptoms is of major clinical interest because these are known to be predictive for adult mood disorders and for a range of other mental health problems. This study investigates the impact of child temperament and early maternal distress, both of which are known to influence children's emotional development, on preadolescent depression. Methods: In a prospective, longitudinal at-risk sample (163 boys, 178 girls), we assessed temperament at the age of 3 months and at 2 years, 4.5 years, and 8 years, respectively, and chronic maternal distress during infancy. Hierarchical linear regression analysis was used to investigate the prediction of depressive symptoms at the age of 11 years measured by the Child Depression Inventory. In addition, we controlled for psychosocial and obstetric perinatal risks and gender. Results: Psychosocial risks and self-control temperament made significant independent contributions to preadolescent depression, whereas fearful, difficult temperament and obstetric risks were unrelated to depressive outcome. Interestingly, a clear gender difference emerged with a significant prediction from maternal distress only in girls. Conclusions: Our data extend previous findings of a concurrent association between regulative temperament and juvenile depression to a predictive view. Furthermore, the results point toward gender-specific pathways to preadolescent depression and support earlier findings indicating that subclinical maternal distress may exert as detrimental effects on child development as clinical depression.
Objective: A difficult or undercontrolled temperament, as well as harsh parental discipline or a lack of warmth, has long been regarded as risk factors for the development of externalizing problems. In addition, it has been suggested that children with difficult temperament are especially susceptible to rearing influences. We investigated the impact of early temperament and parenting and their interactions on externalizing behavior at school age.
Methods: Participants were 148 boys and 160 girls from a prospective longitudinal study on a high-risk sample. At ages 3 months and 2 years, temperament was assessed by a highly structured parent interview and standardized behavioral observations. Maternal parenting was assessed by videotaped behavioral observation and a parent questionnaire. Externalizing problems at age 8 years were measured by the Child Behavior Checklist.
Results: Using hierarchical linear regression analyses, we found that externalizing problems were predicted by psychosocial adversity and poor self-control, whereas no main effect for restrictive parenting or maternal empathy was found. Fearful-inhibited boys were positively affected by empathic and sensitive parenting, whereas girls who were low in self-control and/or fearful developed less externalizing problems with restrictive parenting.
Conclusion: Our results partly support the differential susceptibility hypothesis. In addition, they point toward gender-specific pathways in the development of externalizing problems.
Background: Recent animal and human studies indicate that the exposure to alcohol during early adolescence increases the risk for heavy alcohol use in response to stress. The purpose of this study was to examine whether this effect may be the consequence of a higher susceptibility to develop "drinking to cope" motives among early initiators. Methods: Data from 320 participants were collected as part of the Mannheim Study of Children at Risk, an ongoing epidemiological cohort study. Structured interviews at age 15 and 19 were used to assess age at first alcohol experience and drunkenness. The young adults completed questionnaires to obtain information about the occurrence of stressful life events during the past 4 years and current drinking habits. In addition, alcohol use under conditions of negative states was assessed with the Inventory of Drinking Situations. Results: The probability of young adults' alcohol use in situations characterized by unpleasant emotions was significantly increased the earlier they had initiated the use of alcohol, even when controlling for current drinking habits and stressful life events. Similar results were obtained for the age at first drunkenness. Conclusions: The findings strengthen the hypothesis that alcohol experiences during early adolescence facilitate drinking to regulate negative affect as an adverse coping strategy which may represent the starting point of a vicious circle comprising drinking to relieve stress and increased stress as a consequence of drinking.
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.
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.