GPT and Alzheimer disease: Regarding diagnostic status, ALT levels were significantly decreased (estimate = −0.071, SE = 0.029, p = 0.03), while the AST to ALT ratio and ALP levels were significantly increased in AD compared with CN (AST to ALT ratio: estimate = 1.583, SE = 0.630, p = 0.03; ALP: estimate = 0.036, SE = 0.012, p = 0.02) in the APOE ε4 carrier group (Table 6).