As this mitochondrial enzyme functions to oxidize 3α-hydroxy, 5α-reduced neurosteroids, especially in the hippocampus (He et al., 2005), increased expression and/or activity of 17β-HSD10 contributes to decreased neurosteroid levels in AD (Yang et al., 2014; Porcu et al., 2016). This evidence concerns the gene HSD17B10 and Alzheimer disease.