Objective hot flashes are negatively related to verbal memory performance in midlife women

Abstract

Objective: To test the hypothesis that hot flashes specifically relate to verbal memory performance by examining the relationship between objective hot flashes and cognitive test performance in women with moderate to severe vasomotor symptoms.

Design: In an observational study, 29 midlife women (mean age, 53 y) with moderate to severe hot flashes provided measures of objective hot flashes with an ambulatory hot flash monitor, subjective hot flashes with a diary and questionnaire, and objective measures of verbal memory and other cognitive functions with standardized neuropsychological tests.

Results: The mean number of objective hot flashes was 19.5 per day (range, 6 to 35), including 15.3 (range, 6 to 35) during waking hours and 4.2 (range, 0 to 9) during sleep. The mean sensitivity (ie, subjective detection of objectively measured hot flashes) was 60%. Regression analyses revealed that total number of objective hot flashes, sleep duration, and verbal knowledge were significant predictors of delayed verbal memory. Verbal fluency correlated positively with objective daytime hot flashes. Hot flashes did not predict performance on any of the other secondary cognitive measures (ie, attention, working memory, visual memory), although poor sleep predicted worse performance on several outcome measures.

Conclusions: Highly symptomatic women underreport the number of objective hot flashes that they experience by 43%. Verbal memory performance relates significantly to the objective number of hot flashes women experience but not to the number of hot flashes that they report. These findings suggest that physiological factors related to hot flashes, rather than psychological factors, predict poorer verbal memory function.

FIG. 1

Mean sensitivity (percentage of hot flashes correctly reported) during waking hours and overall. Sensitivity was calculated by dividing the total number of true-positive hot flashes (ie, objectively determined hot flashes that were subjectively detected) by the sum of the total number of objectively measured hot flashes (ie, true positives and false negatives). Of the 29 women in this study, 23 reported nighttime hot flashes, and therefore sensitivity measures were calculated only for those 23 women. Women underreport objective hot flashes by 40% during the day, 50% during the night, and 43% overall (ie, across the full 24 hours).

FIG. 2

Relationship between Logical Memory delayed free recall and average objective hot flashes during sleeping hours controlling for verbal knowledge and sleep duration.