Increased memory load-related frontal activation after estradiol treatment in postmenopausal women

Prior research shows that menopause is associated with changes in cognition in some older women. However, how estrogen loss and subsequent estrogen treatment affects cognition and particularly the underlying brain processes responsible for any cognitive changes is less well understood. We examined the ability of estradiol to modulate the manipulation of information in working memory and related brain activation in postmenopausal women. Twenty healthy postmenopausal women (mean age (SD)=59.13 (5.5)) were randomly assigned to three months of 1mg oral 17-β estradiol or placebo. At baseline and three months later each woman completed a visual verbal N-back sequential letter test of working memory during functional magnetic resonance imaging (fMRI). The fMRI data showed that women who were treated with estradiol for three months had increased frontal activation during the more difficult working memory load conditions compared to women treated with placebo. Performance on the verbal working memory task showed no difference between estradiol and placebo treated subjects. These data are consistent with prior work showing increases in frontal activation on memory tasks after estrogen treatment. However, this is the first study to show that estrogen-induced increases in brain activity were tied to cognitive load during a verbal working memory task. These data suggest that estradiol treatment effects on cognition may be in part produced through modulation of frontal lobe functioning under difficult task conditions.