We report the age-specific incidence and prevalence of dementia and the cumulative lifetime risk of dementia in a prospective cohort study of men who qualified for air crew training in the Second World War. The time frame of the analyses was from 1948 to 2024. Of the 3983 participants, 3960 died, 7 were lost to follow-up and 570 were diagnosed with dementia. The incidence of dementia was low prior to the age of 80 but increased markedly with age thereafter. The prevalence of dementia was also very closely related to age. There was a high competing risk of death.
