Potentially modifiable risk factors for dementia in Norway: the HUNT4 70+ Study

Abstract Background The 2024 Lancet Commission on dementia identified 14 modifiable dementia risk factors. The Norwegian HUNT Study uniquely includes all these factors in the same individuals throughout adulthood. This study evaluates the sex-specific potential for dementia prevention among these factors, adding occupational physical activity, marital-, and employment status. Methods We analyzed data from 9 745 participants aged 70-104 years from the HUNT4 70+ Study (2017-2019), linked with national registries and earlier HUNT surveys (1984-2008) with information covering ages 35-92 years. Clinical experts diagnosed dementia in participants aged 70+. Inverse probability weighting was applied to account for non-response, and logistic regression was used to assess odds of dementia following exposure to low education in early life (<45 years), hearing loss, elevated LDL-cholesterol, depression, traumatic brain injury, physical inactivity, diabetes, smoking, hypertension, obesity, excessive alcohol use in midlife (45-65-years), and social isolation, air pollution, vision loss in later life (≥65 years). In addition, midlife variables on physically demanding work, marital- and employment status, adjusting for confounders, were investigated. The potential for dementia prevention was estimated using population attributable fraction (PAF). Results The PAF for the 14 Lancet Commission risk factors for dementia was 51% (95% confidence interval [CI]; 38-61). By including family and work-related factors, PAF increased to 55% (CI; 42-65). Men had a higher PAF than women; 14 risk factors: 56% (CI; 35.5-70.2) vs. 48% (CI; 29.4-61.7), and 17 risk factors: 57% (CI; 36-71) vs. 52% (CI; 34-65). Conclusions Theoretically, addressing all the 14 modifiable Lancet risk factors for dementia could potentially prevent more than half of all dementia cases at older age, slightly more in men than in women. Aspects in relation to marital - and occupational status have additional risk reduction potential.