KL and Alzheimer disease: In humans, carrying a genetic variant of KLOTHO or having higher levels of klotho has been associated with better cognition or decreased risk of dementia in aging and in Alzheimer’s disease (Dubal et al., 2014; Yokoyama et al., 2015; Belloy et al., 2020; Ali et al., 2022; Kundu et al., 2022).