Although there were no differences between carriers and non-carriers of the Val66Met-allele on demographic, anthropometric or lifestyle factors, it is possible additional environmental factors (e.g., stress, trauma, depression etc.)that were not accounted for in our design and analysis may have impacted the results via gene-environment interactions given their relationship with BDNF (Zhao et al., 2018). This evidence concerns the gene BDNF and major depressive disorder.