title: Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men.
abstract: there are no previous studies linking repeated heat exposure of sauna and the risk of memory diseases. We aimed to investigate whether frequency of sauna bathing is associated with risk of dementia and Alzheimer's disease.
  
  
  
  prospective population-based study.
  
  
  
  the frequency of sauna bathing was assessed at baseline in the Kuopio Ischaemic Heart Disease population-based prospective cohort study of 2,315 apparently healthy men aged 42-60 years at baseline, with baseline examinations conducted between 1984 and 1989. Hazard ratios (HRs) with 95% confidence intervals (CIs) for dementia and Alzheimer's disease were ascertained using Cox-regression modelling with adjustment for potential confounders.
  
  
  
  during a median follow-up of 20.7 (interquartile range 18.1-22.6) years, a total of 204 and 123 diagnosed cases of dementia and Alzheimer's disease were respectively recorded. In analysis adjusted for age, alcohol consumption, body mass index, systolic blood pressure, smoking status, Type 2 diabetes, previous myocardial infarction, resting heart rate and serum low-density lipoprotein cholesterol, compared with men with only 1 sauna bathing session per week, the HR for dementia was 0.78 (95% CI: 0.57-1.06) for 2-3 sauna bathing sessions per week and 0.34 (95% CI: 0.16-0.71) for 4-7 sauna bathing sessions per week. The corresponding HRs for Alzheimer's disease were 0.80 (95% CI: 0.53-1.20) and 0.35 (95% CI: 0.14-0.90).
  
  
  
  in this male population, moderate to high frequency of sauna bathing was associated with lowered risks of dementia and Alzheimer's disease. Further studies are warranted to establish the potential mechanisms linking sauna bathing and memory diseases.
authors.affiliation: Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland.
authors.forename: Tanjaniina
authors.initials: T
authors.lastname: Laukkanen
authors.affiliation: School of Clinical Sciences, University of Bristol, Bristol, UK.
authors.forename: Setor
authors.initials: S
authors.lastname: Kunutsor
authors.affiliation: Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland.
authors.forename: Jussi
authors.initials: J
authors.lastname: Kauhanen
authors.affiliation: Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland.
authors.forename: Jari Antero
authors.initials: JA
authors.lastname: Laukkanen
mesh_terms: D000328:Adult; D000367:Age Factors; D000544:Alzheimer Disease / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control* / Q000523:psychology; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control* / Q000523:psychology; D005387:Finland / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D065840:Protective Factors; D012307:Risk Factors; D012737:Sex Factors; D029002:Steam Bath; D013997:Time Factors
keywords: Alzheimer's disease; Older people; dementia; epidemiology; prospective study