GPT and Alzheimer disease: To my knowledge, this is the first study to examine the plasma AST/ALT ratio and the future risk of cognitive impairment, and we have come to several interesting conclusions: (1) elevated plasma AST/ALT was associated with AD but not with aMCI (Cohort 1); (2) elevated plasma AST/ALT was a risk factor for future cognitive impairment in older adults with normal baseline cognitive function (Cohort 2 and Cohort 3); (3) elevated plasma AST/ALT may contribute to cognitive impairment by affecting right hippocampal volume (Cohort 3).