Data from 330 participants in The 90+ Study, of whom 70% were women, has revealed an overall annual incidence rate of 18.2% for dementia, rising from 12.7% per year in the 90-94 age group, to 21.2% in the 95-99 age group and 40.7% per year in the 100+ age group. 60% of the cases were attributed to Alzheimer's disease, 22% vascular dementia, 9% mixed Alzheimer’s and vascular dementia and 9% other/unknown. Unlike previous findings, rates were very similar for men and women.