Decline in Incidence and Prevalence of Dementia: An Analysis of Outpatient Claims Data.

Background: An increase in dementia is expected worldwide because of the aging of the population. However, recent studies suggest that its incidence is declining.

Methods: Claims data from the German statutory health insurance system (covering 88% of the population) were analyzed for the years 2015 to 2022. Insurees aged 65 and older were included for whom a confirmed diagnosis of dementia was documented in at least two of four consecutive quarters. The incidence and prevalence of dementia were calculated and standardized by age and sex.

Results: The incidence of dementia declined by 26% percent (95% confidence interval: -26.2; -25.3), from 2020 per 100 000 insured individuals in 2015 to 1500 per 100 000 in 2022. Over the same period, its prevalence fell by 18% [-18.6; -18.2], from 10 380 to 8470 per 100 000 insured individuals. These trends were more pronounced in younger age groups and in women and were particularly evident in primary care practices. The number of individuals with a documented diagnosis of dementia fell from 1.56 million in 2015 to 1.43 million in 2022, corresponding to a decline by 8.4% [-8.5; -8.3]. Over the same period, the number of people with a diagnosis of mild cognitive impairment (MCI) increased by 62%, albeit from a very low initial level.

Conclusion: Despite the aging of the population, the incidence and prevalence of diagnosed dementia in German primary care practices are declining. Further analysis is needed to determine whether this is due to a lower individual risk of dementia, changes in diagnostic behavior, or structural factors, such as a shift to specialized memory clinics.