FGF21 and Alzheimer disease: Conversely, plasma levels of FGF21 and GDF15 were shown to increase with aging in humans (Conte et al., 2019; Youm et al., 2016)and these elevations are closely associated with aging‐related chronic diseases, including cardiovascular and metabolic disorders like heart failure, type 2 diabetes, and neurodegenerative diseases like Alzheimer's diseases (Conte et al., 2019; Youm et al., 2016).