Association of hair cortisol concentration with brain-derived neurotrophic factor gene methylation: The role of sex as a moderator.

Hair cortisol concentration (HCC) reflects the long-term activity of the hypothalamus-pituitary-adrenal (HPA) axis in response to stress. Brain-derived neurotrophic factor DNA methylation (BDNF DNA M ) may affect HCC, and sex and Val66Met may contribute to this association. Thus, the aim of this study was to investigate the associations between HCC and Brain-derived neurotrophic factor (BDNF) DNA M , and the moderating effects of Val66Met and sex. We recruited 191 healthy young participants (96 women, mean age 23.0 ± 2.6 years) and collected body samples to evaluate HCC, and to determine BDNF DNA M and Val66Met genotypes. We analyzed the effects of BDNF DNA M , sex, and Val66Met on HCC. We also evaluated the associations between BDNF DNA M and HCC in groups separated by sex and genotypes. We found a marked association of BDNF DNA M with HCC across men and women. After dividing the data by sex, a positive correlation of HCC with BDNF DNA M was found only in women. There was no substantial moderation effect of Val66Met genotypes on the association between BDNF DNA M and HCC. Therefore, BDNF DNA M was found to have positive association with HCC only in healthy young women, indicating that sex moderates the association of BDNF DNA M with long-term HPA axis activity.