Heat and the ageing brain: reading the Finnish dementia data carefully

Dementia Action Week runs from 21 to 27 September. Dementia Australia's message this year is simple: it is time to talk about it.

So we will. Including a statistic about saunas that gets shared a lot, and often without its context.

Why this matters in Australia

Dementia was the leading cause of death in Australia in 2024. The Australian Institute of Health and Welfare estimates about 439,000 Australians were living with dementia in 2025.

The Finnish study

The Kuopio Ischaemic Heart Disease Study followed 2,315 men from eastern Finland, aged 42 to 60 when they joined, for about twenty years. In 2017, researchers published an analysis in Age and Ageing looking at sauna habits and later dementia diagnoses.

After adjusting for age, alcohol, weight, blood pressure, smoking, diabetes, previous heart attack, resting heart rate and cholesterol, men who bathed 4 to 7 times a week had a 66 per cent lower risk of dementia and a 65 per cent lower risk of Alzheimer's disease than men who bathed once a week.

A later and larger Finnish cohort of 13,994 adults, published in 2020, pointed in the same direction.

What it cannot tell us

This is observational research. It shows an association, not proof that sauna prevents dementia.

Men who bathed most often may have differed in ways the researchers could not fully measure: social connection, income, general health. The original cohort was also all men, in a culture where sauna is part of daily life.

The researchers themselves suggested heart health may be part of the link, since what is good for blood vessels tends to be good for the brain. The sense of relaxation may play a role too.

What we would take from it

A regular heat ritual looks like a reasonable part of a brain-friendly life, alongside the things with the strongest evidence: staying active, managing blood pressure and blood sugar, not smoking, and staying socially connected.

We will cover those risk factors later this week.

If this topic is close to home

If you have questions or concerns about memory, or you are caring for someone living with dementia, the National Dementia Helpline is free and available 24 hours a day on 1800 100 500.

Free: The Norge Longevity Guide. Heat, cold and light after 50, with the evidence and the safety rules in one place. Get the guide.

Sources

1. Laukkanen et al., Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men, Age and Ageing, 2017
2. Alzheimer's Drug Discovery Foundation, Can using the sauna reduce risk for Alzheimer's disease? (includes Knekt et al., 2020)
3. Australian Institute of Health and Welfare, Dementia overview
4. Dementia Australia, Dementia Action Week 2026

This article is general information, not medical advice. If you have a heart condition, low blood pressure or are pregnant, speak with your GP before using heat or cold.