After sex-standardization, each 1-SD increase in leptin was associated with hazard ratios of 0.68 for all-cause dementia and 0.60 for AD during a median follow-up period of 8.3 years, after adjusting for age, waist-hip ratio, BMI, systolic blood pressure, antihypertensive medication, diabetes, smoking, cholesterol, homocysteine, and APOE ε4 status [10]. This evidence concerns the gene APOE and dementia.