Gender differences in the incidence of AD and vascular dementia

Objective: To study the difference in risk for dementing diseases between men and women. Background: Previous studies suggest women have a higher risk for dementia than men. However, these studies include small sample sizes, particularly in the older age groups, when the incidence of dementia is highest. Methods: Pooled analysis of four population-based prospective cohort studies was performed. The sample included persons 65 years and older, 528 incident cases of dementia, and 28,768 person-years of follow-up. Incident cases were identified in a two-stage procedure in which the total cohort was screened for cognitive impairment, and screen positives underwent detailed diagnostic assessment. Dementia and main subtypes of AD and vascular dementia were diagnosed according to internationally accepted guidelines. Sex- and age-specific incidence rates, and relative and cumulative risks for total dementia, AD, and vascular dementia were calculated using log linear analysis and Poisson regression. Results: There were significant gender differences in the incidence of AD after age 85 years. At 90 years of age, the rate was 81.7 (95% CI, 63.8 to 104.7) in women and 24.0 (95% CI, 10.3 to 55.6) in men. There were no gender differences in rates or risk for vascular dementia. The cumulative risk for 65-year-old women to develop AD at the age of 95 years was 0.22 compared with 0.09 for men. The cumulative risk for developing vascular dementia at the age of 95 years was similar for men and women (0.04). Conclusion: Compared with men, women have an increased risk for AD. There are no gender differences in risk for vascular dementia.