Estrogen Replacement Therapy in Older Women: Comparisons Between Alzheimer's Disease Cases and Nondemented Control Subjects

Abstract

OBJECTIVES: We hypothesized that oral estrogen replacement therapy would be less common among elderly women meeting criteria for Alzheimer's disease (AD) than among nondemented elderly women. For women with AD, we hypothesized that estrogen users would perform better on a cognitive task than would nonusers. DESIGN: A case-control study of estrogen replacement therapy, in which hierarchical procedures were used to control for potentially confounding effects of age and education. When cognitive performances were compared between estrogen users and nonusers with AD, the duration of dementia symptoms was an additional control variable. SETTING: Alzheimer's Disease Research Center at the University of Southern California, Los Angeles. SUBJECTS: Subjects were a volunteer sample of consecutively enrolled elderly women, recruited primarily from the community, who met clinical criteria for probable AD (n = 143) or met criteria for nondemented control status (n = 92). Seventy case patients who have subsequently died met histopathologic criteria for AD; one other demented woman who did not meet the autopsy criteria for AD was excluded from all analyses. MAIN OUTCOME MEASURES: Current use of estrogen replacement at the time of enrollment as reported by control subjects or by the primary caregivers of AD case patients. Among cases, performances on a brief cognitive screening instrument were compared between estrogen users (n = 10) and nonusers (n = 128) for whom this information was available. RESULTS: Alzheimer's disease case patients were significantly less likely than control subjects to use estrogen replacement (7% vs 18%), but groups did not differ with regard to the total number of prescription medications or to the most frequently prescribed class of drug (thyroid medication). Demented case patients using estrogen did not differ significantly from those not using estrogen in terms of age, education, or symptom duration, but their mean performance on a cognitive screening instrument was significantly better (Mini-Mental State examination scores of 14.9 vs 6.5). CONCLUSIONS: Findings are consistent with contentions that postmenopausal estrogen replacement therapy may be associated with a decreased risk of AD and that estrogen replacement may improve cognitive performance of women with this illness.