The Met allele of BDNF Val66Met polymorphism is associated with increased BDNF levels in generalized anxiety disorder.

Abstract

Generalized anxiety disorder (GAD) is a common psychiatric disorder characterized by long-term worry, tension, nervousness, fidgeting, and symptoms of autonomic system hyperactivity. The neurobiology of this disorder is still unclear, although it has been shown consistently that the environment and the genetic profile could increase its risk. We examined whether a polymorphism in the brain-derived neurotrophic factor (BDNF) gene, which plays a role in neuroplasticity and memory, could increase the vulnerability to this disorder. In our study, 816 participants from a population-based study were genotyped by qPCR for the BDNF functional variant rs6265 (Val66Met) and the BDNF serum levels were measured by ELISA. Our results showed a significant association between the Met allele and risk for GAD (P=0.014), but no differences were observed in the serum levels of BDNF according to diagnosis (P=0.531) or genotype distribution (P=0.197). However, after stratification according to the GAD diagnosis, the Met allele was associated significantly with an increase in serum BDNF levels compared with the Val/Val genotype in GAD participants (F=3.93; P=0.048). The logistic regression analysis confirmed the independent association of Met allele as a risk factor for development of GAD after adjusting for confounder variables (β=0.528; 95% confidence interval: 0.320-0.871; P=0.012). These results suggest that BDNF could be involved in the neurobiology of GAD and might represent a useful marker associated with the disease.