A population-based cohort study that followed 512 initially dementia-free older individuals for 14 years. After controlling for age, gender, educational level, and APOE-ε4 status, they found that anti-HSV1 IgM antibody seropositivity was associated with a significantly increased risk of developing AD (Hazard ratio: 2.55). * The gene discussed is APOE; the disease is dementia.