Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men.
Level 3 - non-randomized controlled study
Prospective population-based cohort study
PubMed 27932366 · doi:10.1093/ageing/afw212
What was done
The Kuopio Ischaemic Heart Disease prospective cohort study assessed baseline sauna bathing frequency among 2,315 apparently healthy Finnish men aged 42 to 60 years examined between 1984 and 1989. Participants were categorized into 1, 2 to 3, or 4 to 7 sauna sessions per week. Cox regression models calculated hazard ratios (HRs) with 95% confidence intervals (CIs) for incident dementia and Alzheimer's disease over a median follow-up of 20.7 years (interquartile range 18.1 to 22.6), adjusting for age, alcohol use, BMI, systolic blood pressure, smoking, type 2 diabetes, previous myocardial infarction, resting heart rate, and LDL cholesterol.
What was found
During follow-up, 204 cases of dementia and 123 cases of Alzheimer's disease occurred. Compared to men having 1 sauna session per week, those having 2 to 3 sessions had an adjusted HR of 0.78 (95% CI: 0.57-1.06) for dementia and 0.80 (95% CI: 0.53-1.20) for Alzheimer's disease. Men having 4 to 7 sessions per week had an adjusted HR of 0.34 (95% CI: 0.16-0.71) for dementia and 0.35 (95% CI: 0.14-0.90) for Alzheimer's disease.
Why it matters
This study provides the first longitudinal evidence linking frequent sauna use to a substantially reduced long-term risk of developing dementia and Alzheimer's disease.
Limits
The cohort included only middle-aged Finnish men, limiting generalizability to women and non-Finnish populations. Sauna habits were assessed only at baseline and could have changed over the 20-year follow-up, and observational design cannot rule out residual confounding or determine biological mechanisms.
Cited by
- supports Studies demonstrate that frequent sauna use significantly reduces the risk of both cardiovascular disease and cognitive decline.