Reduced circulating BDNF is associated with the onset of several neurodegenerative diseases, including Alzheimer’s, Parkinson’s, Multiple Sclerosis, and Huntington’s disease (Ibrahim et al., 2022), as well as psychiatric disorders such as major depressive disorder (Wang et al., 2011; Mojtabavi et al., 2020). This evidence concerns the gene BDNF and major depressive disorder.