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Background: Pavlovian processes are thought to play an important role in the development, maintenance and relapse of alcohol dependence, possibly by influencing and usurping ongoing thought and behavior. The influence of pavlovian stimuli on ongoing behavior is paradigmatically measured by pavlovian-to-instrumental transfer (PIT) tasks. These involve multiple stages and are complex. Whether increased PIT is involved in human alcohol dependence is uncertain. We therefore aimed to establish and validate a modified PIT paradigm that would be robust, consistent and tolerated by healthy controls as well as by patients suffering from alcohol dependence, and to explore whether alcohol dependence is associated with enhanced PIT. Methods: Thirty-two recently detoxified alcohol-dependent patients and 32 age- and gender-matched healthy controls performed a PIT task with instrumental go/no-go approach behaviors. The task involved both pavlovian stimuli associated with monetary rewards and losses, and images of drinks. Results: Both patients and healthy controls showed a robust and temporally stable PIT effect. Strengths of PIT effects to drug-related and monetary conditioned stimuli were highly correlated. Patients more frequently showed a PIT effect, and the effect was stronger in response to aversively conditioned CSs (conditioned suppression), but there was no group difference in response to appetitive CSs. Conclusion: The implementation of PIT has favorably robust properties in chronic alcohol-dependent patients and in healthy controls. It shows internal consistency between monetary and drug-related cues. The findings support an association of alcohol dependence with an increased propensity towards PIT.
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.
Considerable evidence suggests that genetic factors combine with environmental influences to impact on the development of aggressive behavior. A genetic variant that has repeatedly been reported to render individuals more sensitive to the presence of adverse experiences, including stress exposure during fetal life, is the seven-repeat allele of the dopamine D4 receptor (DRD4) gene.
The present investigation concentrated on the interplay of prenatal maternal stress and DRD4 genotype in predicting self-reported aggression in young adults. As disruption of the hypothalamic-pituitary-adrenal system has been discussed as a pathophysiological pathway to aggression, cortisol stress reactivity was additionally examined.
As part of an epidemiological cohort study, prenatal maternal stress was assessed by maternal interview 3 months after childbirth. Between the ages of 19 and 23 years, 298 offspring (140 males, 158 females) completed the Young Adult Self-Report to measure aggressive behavior and were genotyped for the DRD4 gene. At 19 years, 219 participants additionally underwent the Trier Social Stress Test to determine cortisol reactivity.
Extending earlier findings with respect to childhood antisocial behavior, the results revealed that, under conditions of higher prenatal maternal stress, carriers of the DRD4 seven-repeat allele displayed more aggression in adulthood (p = 0.032). Moreover, the same conditions which seemed to promote aggression were found to predict attenuated cortisol secretion (p = 0.028).
This is the first study to indicate a long-term impact of prenatal stress exposure on the cortisol stress response depending on DRD4 genotype.
Theories of decision-making and its neural substrates have long assumed the existence of two distinct and competing valuation systems, variously described as goal-directed vs. habitual, or, more recently and based on statistical arguments, as model-free vs. model-based reinforcement-learning. Though both have been shown to control choices, the cognitive abilities associated with these systems are under ongoing investigation. Here we examine the link to cognitive abilities, and find that individual differences in processing speed covary with a shift from model-free to model-based choice control in the presence of above-average working memory function. This suggests shared cognitive and neural processes; provides a bridge between literatures on intelligence and valuation; and may guide the development of process models of different valuation components. Furthermore, it provides a rationale for individual differences in the tendency to deploy valuation systems, which may be important for understanding the manifold neuropsychiatric diseases associated with malfunctions of valuation.
Alcohol abuse and dependence have proven to be complex genetic traits that are influenced by environmental factors. Primate and human studies have shown that early life stress increases the propensity for alcohol abuse in later life. The reinforcing properties of alcohol are mediated by dopaminergic signaling; however, there is little evidence to indicate how stress alters alcohol reinforcement. KCNJ6 (the gene encoding G-protein-coupled inwardly rectifying potassium channel 2 (GIRK2)) is a brain expressed potassium channel with inhibitory effects on dopaminergic tone. The properties of GIRK2 have been shown to be enhanced by the stress peptide corticotrophin-releasing hormone. Therefore, we sought to examine the role of KCNJ6 polymorphisms in adult alcohol dependence and stress-related alcohol abuse in adolescents. We selected 11 SNPs in the promoter region of KCNJ6, which were genotyped in 1152 adult alcohol dependents and 1203 controls. One SNP, rs2836016, was found to be associated with alcohol dependence (p = 0.01, false discovery rate). We then assessed rs2836016 in an adolescent sample of 261 subjects, which were characterized for early life stress and adolescent hazardous drinking, defined using the Alcohol Use Disorders Identification Test (AUDIT), to examine gene-environment interactions. In the adolescent sample, the risk genotype of rs2836016 was significantly associated with increased AUDIT scores, but only in those individuals exposed to high levels of psychosocial stress in early life (p = 0.01). Our findings show that KCNJ6 is associated with alcohol dependence and may moderate the effect of early psychosocial stress on risky alcohol drinking in adolescents. We have identified a candidate gene for future studies investigating a possible functional link between the response to stress and alcohol reinforcement.
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.
Evidence from animal research has revealed that less maternal care results in disturbed emotionality in the offspring. In the present study, the long-term impact of maternal responsiveness and stimulation during early mother child interaction on depressive psychopathology was examined until adulthood. 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 nursing and playing situation. Maternal responsiveness and stimulation as well as infant responsiveness were evaluated by trained raters. At age 19 years, 314 participants (145 males, 169 females) were characterized on measures of depression through interview and questionnaire. In addition, measures of depression and anxiety were available from assessments in childhood. Results indicated that less maternal stimulation during early interaction was associated with a higher risk of depression in the offspring until the age of 19 years. In addition, children of less stimulating mothers showed more depressive symptoms at age 19 years and displayed more anxiety and depressive symptoms between the ages of 4.5 and 15 years. In contrast, maternal responsiveness was unrelated to children's outcome. In accordance with findings from animal research, the present study provides first longitudinal evidence in humans of a continuous and long-term influence of early maternal interaction behavior on the offspring's psychological adjustment until adulthood. The results suggest that the amount of maternally initiated contact behavior in a very early developmental stage may be crucial for children's mental health, regardless of child and maternal responsiveness.
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.
Background: Clock genes govern circadian rhythms and shape the effect of alcohol use on the physiological system. Exposure to severe negative life events is related to both heavy drinking and disturbed circadian rhythmicity. The aim of this study was 1) to extend previous findings suggesting an association of a haplotype tagging single nucleotide polymorphism of PER2 gene with drinking patterns, and 2) to examine a possible role for an interaction of this gene with life stress in hazardous drinking.
Methods: Data were collected as part of an epidemiological cohort study on the outcome of early risk factors followed since birth. At age 19 years, 268 young adults (126 males, 142 females) were genotyped for PER2 rs56013859 and were administered a 45-day alcohol timeline follow-back interview and the Alcohol Use Disorders Identification Test (AUDIT). Life stress was assessed as the number of severe negative life events during the past four years reported in a questionnaire and validated by interview.
Results: Individuals with the minor G allele of rs56013859 were found to be less engaged in alcohol use, drinking at only 72% of the days compared to homozygotes for the major A allele. Moreover, among regular drinkers, a gene x environment interaction emerged (p = .020). While no effects of genotype appeared under conditions of low stress, carriers of the G allele exhibited less hazardous drinking than those homozygous for the A allele when exposed to high stress.
Conclusions: These findings may suggest a role of the circadian rhythm gene PER2 in both the drinking patterns of young adults and in moderating the impact of severe life stress on hazardous drinking in experienced alcohol users. However, in light of the likely burden of multiple tests, the nature of the measures used and the nominal evidence of interaction, replication is needed before drawing firm conclusions.
Maternal stimulation in infancy predicts hypothalamic-pituitary-adrenal axis reactivity in young men
(2013)
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.