Sauna and brain health: a promising link, with limits
Researchers followed Finnish men for about two decades. Frequent sauna use was linked to fewer dementia diagnoses, but the study does not show prevention.
The short version
Using the same group of 2,315 Finnish men as the 2015 heart-health study, researchers compared sauna habits with later dementia diagnoses over a median of 20.7 years. Men who reported four to seven sessions a week had fewer dementia diagnoses than men who went once a week. It is an interesting link. But it comes from one observational group of men, and it cannot show that sauna prevents dementia.
Keep in mind
The same men as the heart-health study, so not independent confirmation. It shows a link, not prevention.
What they found
Men who reported four to seven sauna sessions a week had a lower rate of dementia diagnoses than men who reported one session a week: a hazard ratio of 0.34 (95% confidence interval 0.16 to 0.71).
The researchers reported a similar pattern for Alzheimer’s disease.
In plain terms, dementia diagnoses were less common among the most frequent sauna users in this cohort. That is a comparison between groups, not a personal risk estimate.
What this means for your practice
This is a promising question for researchers, not a way to protect your memory. The study does not show that sauna prevents dementia.
This does not establish a sauna routine to follow.
Methods and limitations
What the researchers did
This analysis uses the same cohort as our heart-health article: 2,315 middle-aged men in eastern Finland who took part in the Kuopio Ischaemic Heart Disease (KIHD) study, followed for a median of 20.7 years.
The researchers compared how often the men said they used a sauna with who was later diagnosed with dementia. During follow-up, 204 of the men were diagnosed with dementia.
Like the heart-health study, it is observational: nobody was asked to change their sauna habits.
How much can this tell us?
These are the same men as in the 2015 heart-health study. The two findings are not independent confirmation of each other: they come from the same people and share the same strengths and weaknesses.
Men who used the sauna often may have been healthier, more active or more socially connected in ways the statistics could not fully capture. Only men took part, and relatively few of them were in the most frequent sauna group.
The study did not test how sauna might affect the brain. It compared habits with diagnoses, nothing more.
What makes it useful
- A long follow-up: a median of 20.7 years
- A consistent pattern across the sauna frequency groups
What limits it
- Observational: a link, not proof of prevention
- The same men as the heart-health study
- Only men, and few in the most frequent group
Where this study fits
Where this study fits
We score claims, not single studies. This one is part of the evidence for:
Regular sauna protects against dementia. Some support
Low certaintyLarge effectIllness and death
Dementia 66% fewer
Likely 29% to 84%
Fewer cases than the comparison group. The bar is the best estimate, the band behind it the likely range.
From the same participant group as 7 other articles in The Study, so we count them as one group of people.
Read the original
Laukkanen T, Kunutsor S, Kauhanen J, Laukkanen JA. Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men. Age Ageing. 2017;46(2):245-249.
DOI 10.1093/ageing/afw212 · PubMed 27932366