Early menopausal hormone use influences brain regions used for visual working memory

Abstract

The cognitive benefit of postmenopausal hormone use is controversial; however, timing of treatment close to menopause may increase the likelihood of preserving cognitive function. We examined the effects of early-initiation hormone use on visual working memory, hypothesizing that long-term hormone use is associated with greater brain activation during visual working memory. This was a cross-sectional comparison of long-term early hormone users-current (n = 13) and past (n = 24; 2.1 +/- 1.0 years off hormones)-with never users (n = 18), using a visual memory task and functional magnetic resonance imaging (MRI). We evaluated 55 women older than 60 years at the University of Michigan's General Clinical Research Center. Hormone users had completed at least 10 continuous years of conjugated equine estrogens with or without medroxyprogesterone acetate, begun within 2 years of menopause. Women were excluded for illness, medication, intermittent estrogen use, phytoestrogen use, recent smoking, and MRI contraindications. The primary outcome was functional MRI-detected brain activity during the visual memory task. Compared with never users, both groups of hormone users had increased activation in the frontal and parietal cortices, insula, hippocampus, and cingulate; combined hormone users also had increased activation in the putamen and raphe (corrected P < 0.05 or uncorrected P < 0.001 with a priori hypothesis). Across the entire sample, the medial temporal cortex (P < 0.0001 right; P < 0.018 left) and right hippocampus (P < 0.0001) positively correlated with task performance. Hormone use was associated with increased brain activation during the visual memory task, in regions used for visual working memory. A positive correlation between activation and task performance suggests that early-initiation, long-term postmenopausal hormone use may benefit visual working memory.