Background
Increased susceptibility for developing alcohol dependence (AD) might be related to structural differences in brain circuits that influence the salience of rewards and/or modify the efficiency of information processing. The role of the orbitofrontal cortex (OFC) in regulating emotional processing is increasingly being recognized along with its association with impulsive behavior.
Methods
Magnetic resonance imaging was used to measure the OFC in 107 high- and low-risk offspring (mean age 17.6 ± 4.69 years) from either multiplex AD families or control families. Region of interest measures including segmented values were obtained by reliable raters using BRAINS2 software. Statistical analyses were adjusted for intracranial volume, age, socioeconomic status (SES), IQ, and handedness. The Multidimensional Personality Questionnaire (MPQ) was administered to determine scale scores for Control. Genotyping was performed for the serotonin transporter (5-HTT) gene and the brain-derived neurotrophic factor (BDNF) gene.
Results
High-risk offspring from multiplex for AD families showed decreased right/left OFC volumes in comparison with control subjects. Smaller volume in the right hemisphere was significantly associated with variation in the 5-HTT and BDNF genes. White matter (WM) ratios showed a positive correlation with MPQ Control scale scores, indicating that reduced OFC WM is related to greater impulsivity.
Conclusions
Offspring from multiplex families for AD manifest genetic susceptibility by exhibiting disruption in the laterality of the OFC volume that is related to greater impulsivity (lower Control scale scores). This disruption in OFC laterality is related to variation in genes associated with neuronal growth.
Alcoholism is currently one of the most serious public health problems in the US. Lifetime prevalence rates are relatively high with one in five men and one in 12 women meeting criteria for this condition. Identification of genetic loci conferring an increased susceptibility to developing alcohol dependence could strengthen prevention efforts by informing individuals of their risk before abusive drinking ensues. Families identified through a double proband methodology have provided an exceptional opportunity for gene-finding because of the increased recurrence risks seen in these sibships. A total of 360 markers for 22 autosomes were spaced at an average distance of 9.4 cM and genotyping performed for 330 members of these multiplex families. Extensive clinical data, personality variation, and event-related potential characteristics were available for reducing heterogeneity and detecting robust linkage signals. Multipoint linkage analysis using different analytic strategies give strong support for loci on chromosomes 1, 2, 6, 7, 10, 12, 14, 16, and 17.
Objective-To examine the relative importance of prenatal exposure to cigarettes and alcohol and familial/genetic susceptibility for alcohol dependence in the etiology of childhood psychopathology.Method-A longitudinal prospective study of 150 children/adolescents (51.3% male), who were at either high or low risk for developing alcohol dependence because of their familial loading for alcoholism, provided multiple diagnostic assessments (N = 318) of these subjects. High-risk families were identified through the presence of two adult alcoholic sisters; low-risk control families were selected from the community. Annual assessments of offspring from these families included an in-depth psychiatric interview of each child and his/her parent to determine the presence or absence of childhood disorders. Mothers were interviewed concerning their prenatal use of substances, and information was gathered concerning their personal and familial loading for psychiatric disorders.Results-Using conventional logistic regression analyses, internalizing and externalizing disorders were found to be associated with familial loading for alcoholism and prenatal exposure to cigarettes and alcohol. In addition, a specialized statistical analysis, a multivariate confounder score approach, was conducted using familial risk status and the child's exposure to maternal prenatal use of alcohol and cigarettes. This analysis demonstrated that only one relationship between a single variable and a childhood disorder was significant while controlling for the other two variables: Oppositional disorder remained significant in association with familial risk status. Three additional analyses were performed to evaluate the effects of familial risk status, prenatal alcohol exposure and prenatal cigarette exposure on childhood psychopathology while controlling for two known risk factors (SES and parental ASPD) for externalizing disorders. Results of these analyses revealed that the only childhood disorder that was elevated was ADHD, and that this was the result of the familial risk variable only.Conclusions-Familial loading for alcohol dependence is an important risk factor for the development of childhood psychopathology and may account for the previously reported associations between prenatal exposure to nicotine and alcohol. Studies of substance abuse/
Offspring from multiplex families for AD manifest genetic susceptibility by having larger cerebellar volume, which seems to be related to lesser grey matter pruning for age. Larger cerebellar volumes in adult obsessive compulsive disorder (OCD) patients have been reported. This suggests a possible similarity in structural underpinnings for alcohol dependence and OCD.
Multiplex families ascertained through multiple alcohol dependent individuals appear to transmit alcohol and drug use disorders at higher rates than randomly selected families of alcoholics. Our goal was to investigate the risk of developing specific psychiatric diagnoses during childhood or adolescence in association with familial risk status (high-risk [HR] or low-risk [LR]) and parental diagnosis.
Using a prospective longitudinal design, HR offspring from three generation multiplex alcohol dependence families and LR control families were followed yearly. Data analysis was based on consensus diagnoses from 1738 yearly evaluations conducted with the offspring and a parent using the K-SADS, and separately modeled the effects of familial susceptibility and exposure to parental alcohol dependence. Multiplex family membership and parental alcohol and drug dependence significantly increased the odds that offspring would experience some form of psychopathology during childhood or adolescence, particularly externalizing disorders. Additionally, parental alcohol dependence increased the odds that adolescent offspring would have major depressive disorder (MDD). While it is well known that parental substance dependence is associated with externalizing psychopathology, the increased risk for MDD seen during adolescence in the present study suggests the need for greater vigilance of these children.
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