Recent reports indicate that hormone therapy (HT) may have a protective effect on the aging brain. Although previous studies have examined the effects of HT on age-related cognitive changes, there is little information on the effect of a new class of estrogenic agents, selective estrogen receptor modulators (SERMs), on cognitive aging. The two most commonly prescribed SERMs are tamoxifen, for treatment and prevention of breast cancer, and raloxifene, for maintaining bone density. In the face of potential widespread use of SERMs in healthy women, information on the effects of these agents on memory and other cognitive functions is essential.~The principal goals of Co-STAR are to compare the effects of tamoxifen and raloxifene~on age-associated declines in measures of verbal and nonverbal memory in women over age 65~other cognitive abilities and mood~with those resulting from more common forms of HT, specifically ET (conjugated equine estrogen) and ET plus progesterone~Co-STAR results will be compared to results from the Women's Health Initiative Study of Cognitive Aging (WHISCA), a study involving 6-year longitudinal assessment of cognitive outcomes in 2969 women randomly assigned to receive active treatment (Premarin or Premarin plus medroxyprogesterone acetate) or placebo. A comparison of the Co-STAR treatment groups with the group of WHISCA participants receiving placebo will provide insights into the effects of SERMs relative to no treatment. A comparison of the Co-STAR treatment groups with WHISCA treatment groups receiving ET or ET plus progesterone will provide insights into the effects of SERMs relative to common HT treatments.~Co-STAR participants will be recruited from The National Cancer Institute's (NCI) Study of Tamoxifen and Raloxifene (STAR) NCT00003906, a multi-center, 5-year, randomized clinical trial among 22,000 women at increased risk for breast cancer, to compare the effects of tamoxifen and raloxifene on risk for breast cancer.
The purpose of this study is to assess the effects of tamoxifen and raloxifene on cognitive aging in selected cognitively-healthy women.