MAPK3 and Alzheimer disease: For example, irisin can enhance cognitive AD by promoting BDNF production, mitigate AD by reducing Aβ protein deposition, reduce neuroinflammation by inhibiting pro-inflammatory cytokine expression, and protect against AD by activating the Akt/ERK1/2 signaling pathway to inhibit oxidative stress or ameliorate cardiovascular disease (Figure 1).