BACKGROUND: Gender-specific risks for dementia and Alzheimer's disease (AD) starting in midlife remain largely unknown. METHODS: Prospectively ascertained dementia/AD and cause-specific mortality in Framingham Heart Study (FHS) participants was used to generate 10- to 50-year risk estimates of dementia/AD on the basis of the Kaplan-Meier method (cumulative incidence) or accounting for competing risk of death (lifetime risk [LTR]). RESULTS: Overall, 777 cases of incident dementia (601 AD) occurred in 7901 participants (4333 women) over 136,266 person-years. Whereas cumulative incidences were similar in women and men, LTRs were higher in women older than 85 years of age. LTR of dementia/AD at age 45 was 1 in 5 in women and 1 in 10 in men. Cardiovascular mortality was higher in men with rate ratios decreasing from approximately 6 at 45 to 54 years of age to less than 2 after age 65. CONCLUSION: Selective survival of men with a healthier cardiovascular risk profile and hence lower propensity to dementia might partly explain the higher LTR of dementia/AD in women.