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Original Contribution
June 23/30, 2004

Conjugated Equine Estrogens and Global Cognitive Function in Postmenopausal Women: Women's Health Initiative Memory Study

Author Affiliations

Author Affiliations: Departments of Public Health Sciences (Drs Espeland, Rapp, Shumaker, and Dailey, and Ms Hogan) and Psychiatry and Behavioral Medicine (Dr Rapp), Wake Forest University School of Medicine, Winston-Salem, NC; Women's Health Center, University of Nevada School of Medicine, Reno (Dr Brunner); Division of Preventive Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass (Dr Manson); Departments of Psychology and Obstetrics and Gynecology, McGill University, Montreal, Quebec (Dr Sherwin); Department of Medicine, George Washington University, Washington, DC (Dr Hsia); Division of Clinical Epidemiology, Hennepin County Medical Center, Minneapolis, Minn (Dr Margolis); Department of Epidemiology, University of Iowa College of Medicine, Iowa City (Dr Wallace); Department of Obstetrics and Gynecology and Women's Health, Montefiore Medical Center, Bronx, NY (Dr Freeman); and Center for Women's Health, Baylor College of Medicine, Houston, Tex (Dr Hays).

JAMA. 2004;291(24):2959-2968. doi:10.1001/jama.291.24.2959

Context The Women's Health Initiative Memory Study (WHIMS) previously reported that estrogen plus progestin therapy does not protect cognition among women aged 65 years or older. The effect of estrogen-alone therapy, also evaluated in WHIMS, on cognition has not been established for this population.

Objectives To determine whether conjugated equine estrogen (CEE) alters global cognitive function in older women and to compare its effect with CEE plus medroxyprogesterone acetate (CEE plus MPA).

Design, Setting, and Participants A randomized, double-blind, placebo-controlled ancillary study of the Women's Health Initiative (WHI), WHIMS evaluated the effect of CEE on incidence of probable dementia among community-dwelling women aged 65 to 79 years with prior hysterectomy from 39 US academic centers that started in June 1995. Of 3200 eligible women free of probable dementia enrolled in the WHI, 2947 (92.1%) were enrolled in WHIMS. Analyses were conducted on the 2808 women (95.3%) with a baseline and at least 1 follow-up measure of global cognitive function before the trial's termination on February 29, 2004.

Interventions Participants received 1 daily tablet containing either 0.625 mg of CEE (n = 1387) or matching placebo (n = 1421).

Main Outcome Measure Global cognitive function measured annually with the Modified Mini-Mental State Examination (3MSE).

Results During a mean follow-up of 5.4 years, mean (SE) 3MSE scores were 0.26 (0.13) units lower than among women assigned to CEE compared with placebo (P = .04). For pooled hormone therapy (CEE combined with CEE plus MPA), the mean (SE) decrease was 0.21 (0.08; P = .006). Removing women with dementia, mild cognitive impairment, or stroke from the analyses lessened these differences. The adverse effect of hormone therapy was more pronounced among women with lower cognitive function at baseline (all P<.01). For women assigned to CEE compared with placebo, the relative risk of having a 10-unit decrease in 3MSE scores (>2 SDs) was estimated to be 1.47 (95% confidence interval, 1.04-2.07).

Conclusion For women aged 65 years or older, hormone therapy had an adverse effect on cognition, which was greater among women with lower cognitive function at initiation of treatment.