Gut bacteria including inflammation-inducible Odoribacteriaceae, Deferribacteraceae, and Acholeplasmataceae and inflammation-suppressible Akkermansiaceae and Bacteroidaceae may be closely connected with muscle weight and strength by regulating muscle protein biosynthesis-related MyHC/MyoG and muscle degradation-related MuRF1/MAFbx expression and cognitive impairment by regulating hippocampal BDNF expression. The gene discussed is MYH6; the disease is Cognitive impairment.