As the global population ages, the prevalence of dementia is on the rise, creating a pressing need for effective preventive strategies.
While there is no cure for this neurodegenerative condition, emerging research suggests that lifestyle interventions can play a significant role in reducing the risk.
One such intervention that has gained considerable attention is sauna therapy, a practice deeply rooted in Finnish culture.
This article explores the scientific evidence behind sauna therapy’s potential to protect against dementia, delving into the key studies, biological mechanisms, and future directions of this promising area of research.
The Finnish Connection: Foundational Studies
The link between sauna bathing and a reduced risk of dementia was first brought to light by a series of groundbreaking studies conducted in Finland.
A 2017 study by Laukkanen et al. published in Age and Ageing was one of the first to establish this connection [1]. This prospective cohort study followed 2,315 middle-aged men from eastern Finland for over two decades.
The findings were striking: men who used a sauna 4-7 times per week were 66% less likely to be diagnosed with dementia and 65% less likely to be diagnosed with Alzheimer’s disease compared to those who used a sauna only once a week.
A subsequent study in 2020 by Knekt et al., published in Preventive Medicine Reports, expanded on these findings by including both men and women [2].
This larger study, with a follow-up period of 39 years, confirmed the protective effects of frequent sauna bathing. The researchers found that individuals who engaged in sauna bathing 9-12 times per month had a 53% lower risk of dementia during the first 20 years of follow-up and a 19% lower risk over the entire 39-year period compared to those who used a sauna less than four times per month.
These Finnish studies, characterized by their long-term follow-up and large sample sizes, provide a robust foundation for the hypothesis that sauna therapy can be a powerful tool in dementia prevention.
Unlocking the Protective Mechanisms: How Sauna Therapy Affects the Brain
The compelling findings from the Finnish studies have spurred further research into the biological mechanisms that underpin the protective effects of sauna therapy on the brain.
A 2020 review by Von Schulze et al. published in the Journal of Applied Physiology sheds light on these intricate processes [3]. The review highlights the central role of heat shock proteins (HSPs), which are activated by the heat stress of a sauna.
HSPs are molecular chaperones that help maintain cellular health by refolding damaged proteins, removing nonfunctional proteins, and protecting against oxidative stress.
With age, the body’s natural production of HSPs declines, leaving brain cells more vulnerable to the protein aggregation and damage that are hallmarks of neurodegenerative diseases like Alzheimer’s.
Sauna therapy, by inducing the production of HSPs, may help to counteract these age-related changes and bolster the brain’s resilience.
Another critical mechanism is the effect of sauna therapy on insulin resistance. Insulin resistance in the brain has been strongly linked to an increased risk of dementia.
It can disrupt the clearance of amyloid-beta plaques and contribute to the formation of tau tangles, two of the primary pathological features of Alzheimer’s disease.
The heat from a sauna can improve the body’s sensitivity to insulin, which in turn can help to maintain healthy brain function and reduce the risk of cognitive decline.
Furthermore, sauna therapy has been shown to improve vascular function. A healthy cardiovascular system is essential for brain health, as it ensures a steady supply of oxygen and nutrients to brain cells.
Sauna bathing can improve blood flow, reduce blood pressure, and enhance the function of the endothelial cells that line the blood vessels.
These cardiovascular benefits can have a direct positive impact on the brain, protecting it from the damage that can lead to dementia.
Finally, sauna therapy may also promote brain health by improving mitochondrial function.
Mitochondria are the powerhouses of our cells, and their dysfunction is increasingly recognized as a key factor in the aging process and the development of neurodegenerative diseases.
The heat stress from a sauna can stimulate a process called mitophagy, which is the selective removal of damaged mitochondria. This process helps to maintain a healthy population of mitochondria, ensuring that brain cells have the energy they need to function optimally.
Beyond the Finnish Sauna: Exploring Different Types of Heat Therapy
While the most compelling evidence for dementia prevention comes from studies on traditional Finnish saunas, it is important to recognize that other forms of passive heat therapy may also offer cognitive benefits.
A 2024 comprehensive review by Laukkanen and Kunutsor, published in Temperature, provides an overview of the various types of heat therapy that are available [4]. These include:
- Hot tubs and hydrotherapy: Immersion in hot water can provide a similar physiological response to a sauna, raising the body’s core temperature and inducing a state of relaxation.
- Waon therapy: This is a Japanese form of thermal therapy that involves sitting in a far-infrared dry sauna maintained at a constant temperature of 60°C (140°F) for 15 minutes.
- Infrared saunas: These saunas use infrared heaters to warm the body directly, rather than heating the air. They operate at lower temperatures than traditional Finnish saunas, which may be more comfortable for some individuals.
- Steam baths: These involve sitting in a room filled with high-humidity steam, which can help to open up the airways and promote sweating.
While more research is needed to determine the specific cognitive benefits of each of these heat therapies, the underlying principle remains the same: by raising the body’s core temperature, these therapies can trigger a cascade of physiological responses that may help to protect the brain from the effects of aging and neurodegeneration.
The Future of Heat Therapy for Dementia Prevention: Clinical Trials and New Frontiers
The promising findings from observational studies have paved the way for more rigorous clinical trials to investigate the potential of heat therapy as a preventive strategy for dementia.
One such study is the FIGHT-AD (Finns Investigating Glycemic control via Heat Therapy for Alzheimer’s Disease) pilot study [5].
This ongoing trial is exploring whether hot water immersion can improve glucose metabolism in the brain and body of older adults who are at risk for Alzheimer’s disease. The results of this study, and others like it, will be crucial in establishing the causal link between heat therapy and a reduced risk of dementia.
Another exciting area of research is the potential for combining heat therapy with other lifestyle interventions, such as exercise and a healthy diet.
A 2020 review by Hunt et al. published in Frontiers in Physiology suggests that passive heat therapy may be a particularly valuable tool for individuals who are unable to engage in regular physical activity due to physical limitations [6].
By providing a way to reap some of the cardiovascular and metabolic benefits of exercise without the physical strain, heat therapy could offer a new avenue for promoting brain health in a wider range of individuals.
As our understanding of the complex interplay between heat, the brain, and the aging process continues to grow, we can expect to see even more innovative approaches to harnessing the power of heat for dementia prevention.
From personalized heat therapy protocols to the development of new technologies that make heat therapy more accessible, the future of this field is bright.
A Promising Strategy for a Healthier Brain
The evidence is mounting that sauna therapy, a simple and enjoyable practice, may be a powerful tool in the fight against dementia.
The long-term observational studies from Finland, coupled with a growing body of research on the underlying biological mechanisms, provide a compelling case for the regular use of saunas as a means of promoting brain health and reducing the risk of cognitive decline.
While more research is needed to fully understand the optimal frequency, duration, and type of heat therapy for dementia prevention, the existing evidence is strong enough to suggest that incorporating sauna bathing into a healthy lifestyle is a wise investment in our long-term cognitive well-being.
References
[1] Laukkanen, T., Kunutsor, S., Kauhanen, J., & Laukkanen, J. A. (2017). Sauna bathing is inversely associated with dementia and Alzheimer’s disease in middle-aged Finnish men. Age and Ageing, 46(2), 245-249. https://academic.oup.com/ageing/article-abstract/46/2/245/2654230
[2] Knekt, P., Järvinen, R., Rissanen, H., Heliövaara, M., & Aromaa, A. (2020). Does sauna bathing protect against dementia?. Preventive Medicine Reports, 20, 101221. https://pmc.ncbi.nlm.nih.gov/articles/PMC7560162/
[3] Von Schulze, A. T., Deng, F., Morris, J. K., & Geiger, P. C. (2020). Heat therapy: possible benefits for cognitive function and the aging brain. Journal of Applied Physiology, 129(6), 1468-1476. https://pmc.ncbi.nlm.nih.gov/articles/PMC7792844/
[4] Laukkanen, J. A., & Kunutsor, S. K. (2024). The multifaceted benefits of passive heat therapies for extending the healthspan: A comprehensive review with a focus on Finnish sauna. Temperature, 11(1), 27-51. https://pmc.ncbi.nlm.nih.gov/articles/PMC10989710/
[5] Blankenship, A. E., et al. (2024). Improving glycemic control via heat therapy in older adults at risk for Alzheimer’s disease (FIGHT-AD): a pilot study. Journal of Applied Physiology. https://journals.physiology.org/doi/abs/10.1152/japplphysiol.00396.2024
[6] Hunt, A. P., Minett, G. M., Gibson, O. R., Kerr, G. K., & Stewart, I. B. (2020). Could Heat Therapy Be an Effective Treatment for Alzheimer’s and Parkinson’s Diseases? A Narrative Review. Frontiers in Physiology, 10, 1556. https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2019.01556/full
