Brain-derived neurotrophic factor (BDNF) Val66Met and adulthood chronic stress interact to affect depressive symptoms

Background: BDNF Val66Met by chronic stress interaction has been studied using childhood stress as a moderator, but has not been widely studied using chronic stress in adulthood. Methods: Two independent samples were used: Duke-CG (238 Caucasians) and MESA (5524 Caucasians, African Americans and Hispanics). Chronic stress in Duke-CG was operationalized as having primary caregiving responsibility for a spouse or relative with diagnosed Alzheimer's disease or other major dementia; chronic stress in MESA was defined using chronic burden score constructed from self-reported problems of health (self and someone close), job, finance and relationships. CES-D scale was the measure of depression in both samples. The BDNF Val66Met by adulthood chronic stress interaction predicting CES-D was examined using linear regression, adjusted for covariates. Results: The main effect of BDNF Val66Met genotype on CES-D scores was non-significant (ps > 0.607) but the adulthood chronic stress indicator was significant (ps < 0.001) in both samples. The BDNF Val66Met genotype by adulthood chronic stress interaction was also significant (ps < 0.039) in both samples. The impact of chronic stress in adulthood on CES-D scores was significantly larger in Val/Val genotype individuals than Met carriers. Conclusion: We found in two independent samples that depression levels increased significantly more as a function of adulthood chronic stress Val/Val genotype carriers than Met carriers. Individuals with the Val/Val genotype and chronic stress exposure could be targeted for interventions designed to reduce risk of depression if this finding is confirmed in future studies. (c) 2012 Elsevier Ltd. All rights reserved.