The relation of BDNF VAL66MET polymorphism to neural volume and drinking behavior among adolescents

Brain-Derived Neurotrophic Factor (BDNF) plays an important role in neural plasticity, learning and memory. Due to its relation to neurogenesis, BDNF has been studied with respect to its protective effects against various cognitive dysregulations, including those related to alcohol dependence. Recent evidence suggests that alcohol dependent individuals, in addition to those with a family history of alcoholism, have lower basal levels of BDNF as compared to controls. In adult populations, the Met variant of the Val66Met polymorphism, which results in decreased release of BDNF, has been associated with decreased neural volume as well as increased risk for alcohol problems. Using samples with prolonged alcohol exposure makes it difficult to determine the direction of the relationship between neural volume and drinking behavior. Therefore the current study set out to determine whether a relationship between BDNF, neural volume and drinking behavior could be detected using a sample of adolescents. Since this relationship is well demonstrated using adult samples, it was hypothesized that BDNF genotype would be correlated with drinking behavior among adolescents, and this relationship would be mediated by differences in neural volume. 220 adolescents gave saliva samples, participated in magnetic resonance imaging (MRI), and completed behavioral measures designed to assess drinking behavior. Although BDNF was not correlated with drinking behavior, other interesting relationships were discovered including an inverse relationship between age and cerebral cortex volume, a positive relationship between accumbens volume and drinking, and distinct findings based on gender