Association between Relative Hypothermia and Cognitive Function in Older Adults: A Cross-Sectional Study.

Objectives: This study aimed to investigate the association between relative hypothermia measured by a wearable device and cognitive function, and to clarify whether relative hypothermia is a useful indicator for preventing poor cognitive function.

Design: Cross-sectional study.

Setting And Participants: The study included 103 community-dwelling older adults aged 60 to 90 years.

Methods: This study measured body temperature with a wrist-worn device equipped with an accelerometer. Subjects were instructed to wear the Silmee 24 hours a day for 1 week, and body temperature data were sampled every minute. Relative hypothermia was calculated as the percentage of time during the daytime active phase in which body temperature was below the 24-hour mean body temperature. Cognitive function was evaluated regarding memory, attention, executive function, processing speed, and general cognitive function. We calculated atrophy within regions of interest such as the parahippocampal gyrus, hippocampus, and amygdala, which show atrophy in the early stages of Alzheimer's disease. Multiple regression analysis was performed, taking into account variables such as age, sex, body mass index, and severity of volume of interest (VOI) atrophy.

Results: Relative hypothermia was significantly associated with memory function. Multiple regression analysis considering variables such as age and severity of VOI atrophy also showed that relative hypothermia was independently associated with the decline in memory function.

Conclusions And Implications: Relative hypothermia was independently associated with the decline in memory function. Our findings suggest that relative hypothermia assessed by a wearable device may be a useful indicator for early prevention of poor cognitive function.