Objective: Accumulating biologic evidence suggests that estrogen is related to cognitive function. Several epidemiologic investigations have reported that hormone therapy may reduce the risk of Alzheimer's disease. However, fewer studies have examined the relation of postmenopausal hormone use to general cognitive function in nondemented older women. Thus, we examined the association of hormone therapy to performance on four cognitive tests among healthy participants of the Nurses' Health Study.
Design: Cohort study.
Setting: The Nurses' Health Study, an ongoing prospective cohort study begun in 1976.
Participants: From the Nurses' Health Study, 2138 women aged 70-78 years.
Measurements: From 1995-1999 we administered four cognitive tests (Telephone Interview for Cognitive Status (TICS), immediate and delayed recall of the East Boston Memory Test (EBMT), and verbal fluency) by telephone. Hormone use was ascertained from biennial questionnaires beginning in 1976. Linear and logistic regression models were used to calculate multivariate-adjusted differences in scores and relative risks of a low score for never users compared to current and past hormone users.
Results: After adjustment for confounders, neither current nor long-term hormone users demonstrated better performance on an overall measure of cognition (TICS), or on three tests of verbal memory (immediate and delayed recall of the EBMT, immediate recall of the TICS 10-word list) than never users. On the test of verbal fluency, current hormone users scored significantly better than never users (linear regression estimate of the difference in score = 0.78 points, 95% confidence interval (CI) 0.19-0.38, P = .01 for any current use; and 0.91 points, 95% CI 0.28-1.54, P = .005 for > or = 5 years current use). Current hormone users also had a 30% decrease (RR = 0.70, 95% CI 0.45-1.09) in their risk of a low score on the test of verbal fluency. These results were similar for women taking estrogen alone and estrogen combined with a progestin.
Conclusions: Verbal fluency may be enhanced among women taking postmenopausal hormones, however, there is little support for better overall cognitive function in hormone users than nonusers.