Editors’ note: Sauna bathing reduces the risk of stroke in Finnish men and women: A prospective cohort study

In the article “Sauna bathing reduces the risk of stroke in Finnish men and women: A prospective cohort study,” Kunutsor et al. reported a reduced risk of stroke in sauna bathers over a median follow-up of 14.9 years in middle-aged to elderly participants in the Finnish Kuopio Ischemic Heart Disease prospective cohort study. In response, Yu et al. suggest that the status of intracranial vasculature be included in the analysis as it may influence hemodynamic responses to sauna exposure. Dippel et al. highlight the risk of healthy volunteer bias and the absence of a sauna-naive reference group, and also note the lack of an adequate biological explanation for protective effects seen not only in stroke but also in other diseases. Replying to these comments, Kunutsor et al. note that they did not have vascular imaging data but contend that their Caucasian cohort was less likely to have significant asymptomatic intracranial atherosclerosis. While acknowledging potential limitations of selection bias, they emphasize relevant strengths of their study, and cite evidence on beneficial effects of sauna exposure on factors like blood pressure and inflammation that are implicated in stroke, Alzheimer disease, and respiratory conditions.