Improving Glycemic Control via Heat Therapy in older adults at risk for Alzheimer's Disease (FIGHT-AD): a pilot study.

Impaired glycemic control increases the risk for type 2 diabetes (T2D) and Alzheimer's Disease (AD). Heat therapy (HT), via hot water immersion (HWI), has shown promise in improving shared mechanisms implicated in both T2D and AD, like blood glucose regulation, insulin sensitivity, and inflammation. The potential for HT to improve brain health in individuals at risk for AD has not been examined. This pilot study aimed to assess the feasibility and adherence of utilizing HT in cognitively healthy older individuals at risk for AD due to existing metabolic risk factors. Participants underwent four weeks of HT (three sessions/week) via HWI, alongside cognitive screening, self-reported sleep characterization, glucose tolerance tests, and MRI scans pre- and post-intervention. A total of 18 participants (9 male, 9 female; mean age: 71.1 ± 3.9 years), demonstrating metabolic risk, completed the intervention. Participant adherence for the study was 96% (8 missed sessions out of 216 total sessions), with one study related mild adverse event (mild dizziness/nausea). Overall, the research participants responded to a post-intervention survey saying they enjoyed participating in the study and it was not a burden on their schedules. Secondary outcomes of the HT intervention demonstrated significant changes in mean arterial pressure, diastolic blood pressure, and cerebral blood flow p<0.05), with a trend toward improved body mass index (p=0.06). Future studies, including longer durations and a thermoneutral control group, are needed to fully understand heat therapy's impact on glucose homeostasis and potential to improve brain health.