FGF23 and Cognitive impairment: Potential activity-induced candidate myokines that have been associated with cognitive function include: Klotho and brain-derived neurotrophic factor (BDNF), which regulate neuronal survival and growth and protect from cardiovascular or cognitive impairment (9–12); fibroblast growth factor 23 (FGF23) and Klotho co-receptor, which may impact brain function, resulting in hippocampal-dependent cognitive impairment if lacking (13–15); and interleukin-6 (IL-6), a pro-inflammatory marker involved in neuroinflammation, which during exercise has an anti-inflammatory effect (5, 16–18).