Systematic review and meta-analysis of the effects of menopause hormone therapy on risk of Alzheimer’s disease and dementia
Matilde Nerattini, Steven Jett, Caroline Andy, Caroline Carlton, Camila Zarate, Camila Boneu, Michael T. Battista, Silky Pahlajani, Susan Loeb‐Zeitlin, Yelena Havryulik, Schantel Williams, Paul J. Christos, Matthew E. Fink, Roberta Dı́az Brinton, Lisa Mosconi
Abstract
Introduction Despite a large preclinical literature demonstrating neuroprotective effects of estrogen, use of menopausal hormone therapy (HT) for Alzheimer’s disease (AD) risk reduction has been controversial. Herein, we conducted a systematic review and meta-analysis of HT effects on AD and dementia risk. Methods Our systematic search yielded 6 RCT reports (21,065 treated and 20,997 placebo participants) and 45 observational reports (768,866 patient cases and 5.5 million controls). We used fixed and random effect meta-analysis to derive pooled relative risk (RR) and 95% confidence intervals (C.I.) from these studies. Results Randomized controlled trials conducted in postmenopausal women ages 65 and older show an increased risk of dementia with HT use compared with placebo [RR = 1.38, 95% C.I. 1.16–1.64, p < 0.001], driven by estrogen-plus-progestogen therapy (EPT) [RR = 1.64, 95% C.I. 1.20–2.25, p = 0.002] and no significant effects of estrogen-only therapy (ET) [RR = 1.19, 95% C.I. 0.92–1.54, p = 0.18]. Conversely, observational studies indicate a reduced risk of AD [RR = 0.78, 95% C.I. 0.64–0.95, p = 0.013] and all-cause dementia [RR = .81, 95% C.I. 0.70–0.94, p = 0.007] with HT use, with protective effects noted with ET [RR = 0.86, 95% C.I. 0.77–0.95, p = 0.002] but not with EPT [RR = 0.910, 95% C.I. 0.775–1.069, p = 0.251]. Stratified analysis of pooled estimates indicates a 32% reduced risk of dementia with midlife ET [RR = 0.685, 95% C.I. 0.513–0.915, p = 0.010] and non-significant reductions with midlife EPT [RR = 0.775, 95% C.I. 0.474–1.266, p = 0.309]. Late-life HT use was associated with increased risk, albeit not significant [EPT: RR = 1.323, 95% C.I. 0.979–1.789, p = 0.069; ET: RR = 1.066, 95% C.I. 0.996–1.140, p = 0.066]. Discussion These findings support renewed research interest in evaluating midlife estrogen therapy for AD risk reduction.