The number of people in the United States who develop dementia each year will double over the next 35 years to about one million annually by 2060, a new study estimates, and the number of new cases per year among Black Americans will triple. The increase will primarily be due to the growing aging population, as many Americans are living longer than previous generations. By 2060, some of the youngest baby boomers will be in their 90s and many millennials will be in their 70s. Older age is the biggest risk factor for dementia. The study found that the vast majority of dementia risk occurred after age 75, increasing further as people reached age 95.