HSD11B1 and Mental deterioration: Importantly, because of the many physiological, neuronal and endocrine similarities between rhesus macaques and humans (Messaoudi et al., 2011; Sorwell et al., 2012; Stonebarger et al., 2021), the results support the idea that an age-related increase in HSD11B1 expression in the hippocampus, together with elevated circulating cortisol levels, predispose this vulnerable brain area to neurotoxicity, cognitive decline and ultimately to development of dementia in the elderly.