Menopausal Hot Flashes and the Default Mode Network

Objective To test whether more physiologically assessed hot flashes were associated with greater connectivity in the default mode network (DMN), the network of brain regions active during rest. We particularly focus on DMN networks supporting the hippocampus as this region is rich in estrogen receptors and has previously been linked to hot flashes. Design Women underwent 24 hours of physiologic and diary hot flash monitoring, functional magnetic resonance imaging, 72 hours of sleep actigraphy monitoring, a blood draw, questionnaires, and physical measures. Setting Community Participants Twenty midlife women ages 40–60 with their uterus and both ovaries and not taking hormone therapy Interventions None Main outcome measures DMN functional connectivity Results Controlling for age, race, education, a greater number of physiologically-monitored hot flashes were associated with greater DMN connectivity [beta, B (standard error, SE)=.004 (.002), p<.05], particularly hippocampal DMN connectivity [B(SE)=.005 (.002), p<.05]. Findings were most pronounced for sleep physiologic hot flashes [with hippocampal DMN, B(SE)= .02 (.007), p<0.01]. Associations persisted additionally controlling for sleep, depressive symptoms, and serum estradiol concentrations. Conclusions More physiologically-monitored hot flashes were associated with greater DMN connectivity, particularly networks supporting the hippocampus. Findings were most pronounced for sleep hot flashes. Findings underscore the importance of continued investigation of the central nervous system in efforts to understand this classic menopausal phenomenon.