BDNF val66met genotype shows distinct associations with the acoustic startle reflex and the cortisol stress response in young adults and children

Brain Derived Neurotrophic Factor (BDNF) is a crucial regulator of neuronal development, organization and function and the val(66)met polymorphism in the BDNF gene has been associated with several (endo-) phenotypes of cognitive and affective processing. The BDNF met allele is considered a risk factor for anxiety and fear related phenotypes although findings are not entirely consistent. Here, the impact of BDNF val(66)met on two parameters of anxiety and stress was investigated in a series of studies. Acoustic startle responses were assessed in three adult samples (N-1 =117, N-2 =104, N-3 = 116) as well as a children sample (N-4 =123). Cortisol increase in response to the Trier Social Stress Test (TSST) was measured in one adult sample (N-3) and in the children sample (N-4). The BDNF met allele was associated with enhanced cortisol responses in young adults (p = 0.039) and children (p = 0.013). On the contrary, BDNF met allele carriers showed a reduced acoustic startle response which reached significance in most samples (N-1: p = 0.004; N-2: p = 0.045; N-3: n.s., N-4: p = 0.043) pointing to differential effects of BDNF val(66)met on distinct endophenotypes of anxiety and stress-related responses. However, small effect sizes suggest substantial additional genetic as well as environmental contributors. (C) 2015 Elsevier Ltd. All rights reserved.