THE ASSOCIATION BETWEEN BDNF POLYMORPHISM AND BIOMARKERS OF STRESS IN MIDDLE AGED AND OLDER ADULTS

Abstract

Stress exposure over the lifespan is robustly associated with accelerated cognitive decline in late life. Researchers continue to investigate factors that determine individual differences in stress physiology. Brain derived neurotrophic factor is found to associate with cognitive trajectory in late life, and the Met allele of the functional Val66Met BDNF gene has been found to associate with poorer episodic memory and executive functioning in late life. The objective of this study was to evaluate the association between BDNF polymorphism and indices of stress among adults aged 50+. Community dwelling middle aged and older adults provided a blood sample for BDNF genotyping. Participants also sampled their saliva five times a day over three consecutive days for measurement of diurnal cortisol and underwent the Trier Social Stress Test (TSST) for measurement of stress reactivity. Among 120 adults aged 50–67 (83% female, 89% Caucasian), 73 participants were Val/Val carriers and 47 carried one copy of the Met allele (45 Val/Met, 2 Met/Met carriers). Val/Val and Met carriers did not differ on any demographic factors. Repeated measures analyses did not reveal an association between BDNF genotype and diurnal salivary cortisol (p=.63); however, analyses revealed that Met carriers displayed a blunted cortisol response to the TSST compared with Val/Val carriers, F(9, 936)=2.09, p=.03. This is the first study to evaluate the role of BDNF polymorphism in stress physiology among middle-aged and older adults. Future studies are needed to evaluate lifespan interconnections between BDNF, stress physiology and cognitive function.