Prevalence and co-occurrence of dementia risk factors in Denmark: A nationwide study.

Background: The clustering of dementia risk factors is common and has implications for policies targeting risk reduction.

Objectives: To estimate the prevalence of 16 dementia risk factors and their co-occurrence.

Design: Cross-sectional based on a closed cohort on 1 January 2022 with nationwide data on risk factors from 1969/1977.

Setting: Denmark PARTICIPANTS: Whole population; closed cohort of individuals ≥65 years on 1 January 2022, and a subpopulation of responders in the 2010/2013 Danish National Health Survey.

Intervention (exposures): Sixteen dementia risk factors: hypertension, cardiovascular disease, diabetes, hypercholesterolemia, obesity, smoking, alcohol, physical inactivity, depression, hearing loss, vision impairment, traumatic brain injury, sleep disorders, hospital-diagnosed infections, social isolation, and low education.

Measurements: Period and point prevalence proportions of the dementia risk factors and of all possible combinations of factors (those occurring in ≥10 % of individuals). The prevalence estimates reflect a population-level view of persons who have experienced, were diagnosed, or were treated for the risk factors assessed.

Results: In the whole population (N = 1,214,286) and the subpopulation (N = 88,565), 5 % had no risk factors, 12 % had only one, and 82 % had multiple. Hypertension was the most prevalent (57 %), and vision impairment the least (2 %). Men, individuals ≥85 years, and those with low education had the highest prevalence of risk factors (with exceptions).

Conclusions: Clustering of risk factors is very common, and findings emphasize the need to focus on multidomain interventions for dementia risk reduction that account for the clustering of risk.