Twenty-seven-year time trends in dementia incidence in Europe and the United States: The Alzheimer Cohorts Consortium.
Level 3 - non-randomized controlled study
Pooled analysis of 7 population-based prospective cohort studies.
PubMed 32611641 · doi:10.1212/WNL.0000000000010022
What was done
Researchers analyzed aggregated data from 49,202 individuals aged over 65 across 7 population-based prospective cohort studies in the United States and Europe participating in the Alzheimer Cohort Consortium. Age- and sex-specific incidence rates of all-cause dementia were calculated across non-overlapping 5-year epochs between 1988 and 2015. Trends were pooled to estimate the relative change in dementia incidence per 10-year calendar interval, both overall and stratified by sex.
What was found
Over the study periods, 4,253 of 49,202 participants (8.6%) developed dementia. Dementia incidence rose steeply with age, ranging from approximately 4 per 1,000 person-years at ages 65–69 to 65 per 1,000 person-years at ages 85–89. Overall dementia incidence declined by 13% per calendar decade (95% CI, 7%–19%). The reduction was more pronounced in men (24% decline per decade; 95% CI, 14%–32%) than in women (8% decline per decade; 95% CI, 0%–15%).
Why it matters
This study provides multi-cohort confirmation that age-specific dementia risk has been falling over recent decades in high-income Western countries, suggesting that modifiable risk factor profiles or educational attainment may influence population-level risk.
Limits
The analysis is restricted to European and US cohorts, limiting generalizability to low- and middle-income nations and ethnically diverse populations. The abstract does not measure or adjust for specific causal mechanisms (such as cardiovascular management or lifestyle shifts) underlying the temporal decline.
Cited by
- supports Age-adjusted incidence rates of Alzheimer's disease among 75- and 80-year-olds have been declining over the past two to three decades.