No, a regular sauna probably doesn’t protect against dementia

Regular sauna visits may reduce the risk of dementia, according to a study at the University of Eastern Finland (however, see our analysis below).

The researchers found that men who went for a sauna between four and seven times a week were 66 per cent less likely to be diagnosed with dementia (over a 20-year period) than those taking a sauna once a week.

The Kuopio Ischaemic Heart Disease Risk Factor Study involved more than 2,000 middle-aged men living in the eastern part of Finland. Participants were divided into three groups: those taking a sauna once a week, those taking a sauna two to three times a week, and those taking a sauna four to seven times a week.

The researchers found that the more frequently saunas were taken, the lower the risk of dementia was. Among those taking a sauna four to seven times a week, the risk of any form of dementia was 66 per cent lower and the risk of Alzheimer’s disease 65 per cent lower than among those taking a sauna once a week.

The study, published in the Age and Ageing journal, did not establish causality.

The same data showed a correlation between frequency of sauna use and a lower risk of sudden cardiac death, coronary artery disease and other cardiac events, as well as overall mortality.

The study’s lead author, Jari Laukkanen, says that sauna bathing may protect the heart and memory via similar, poorly understood mechanisms. ‘It is known that cardiovascular health affects the brain as well. The sense of well-being and relaxation experienced during sauna bathing may also play a role,’ he says.

Instant analysis
The title of the study is ‘Sauna bathing is inversely associated with dementia and Alzheimer’s disease in middle-aged Finnish men’ and the operative word here is associated. An association, or relationship between two variables such as dementia and sauna bathing, does not mean causation. While changes in one variable may cause changes in the other, it may also be the other way round, that dementia causes less use of sauna facilities, or a third factor altogether that influences both — for instance, physical activity.

That said, it is a large study on more than 2,000 Finnish men over a significant time period, which make its findings applicable to the Finnish male population at large. The prevalence of dementia in Finland is the ninth highest in Europe (the UK is 33rd) and there are over three million saunas in Finland for only five million inhabitants, so clearly sauna use is also high. After controlling for possible confounding (influencing) variables such as blood pressure, smoking, body mass index and others, it appears this relationship was maintained, suggesting the association is real. The absence of women means we don’t know if they would be similarly affected by sauna use.

Furthermore, no indication of possible mechanisms are given. There are other possible confounders that are not controlled for, such as family history of dementia, ethnicity, diet, depression and physical activity. Also, such studies are inherently unreliable as they rely on the participants to recall how many sauna sessions they had, which they may forget, recall wrongly or incorrectly to please the investigator.

Personally, I would prefer the public, if worried about dementia, to spend a few episodes a week engaging in physical activity rather than being sat inactive in a hot room naked. I would take these results with a large pinch of steam.
DW
Research score: 1/5


  • Szymon Dominik

    1. It seems like this article refers just to the abstract – not the whole paper. The analysis was correctly adjusted for “potential confounders selected on the basis of their previously established role as risk factors”. Diet, physical activity and others were taken into account. Anyway, it is an observational study, that is you cannot exclude all potential risk factors from the study.

    2. “no indication of possible mechanisms are given.” Firstly, the cause of dementia itself is not completely understood. Secondly, in the paper the authors shortly indicate that, for example, sauna could reduce inflammation. Thirdly, it is, once again, observational study – and not basic science.

    3. The title that “sauna probably doesn’t protect against dementia” is completely misleading as there is no further evidence/indication in the article that sauna does not protect against neurodegeneration. There is a lot on the methodological aspect of the study but not the science itself. It is completely non-scientific title.

    Pardon my english.

    Article score: 0/5