Cognitive factors associated with adherence to oral antiestrogen therapy: results from the cognition in the study of tamoxifen and raloxifene (Co-STAR) study

Cancer Prev Res (Phila). 2014 Jan;7(1):161-8. doi: 10.1158/1940-6207.CAPR-13-0165. Epub 2013 Nov 19.


Little is known about the cognitive factors associated with adherence to antiestrogen therapy. Our objective was to investigate the association between domain-specific cognitive function and adherence among women in a clinical prevention trial of oral antiestrogen therapies. We performed a secondary analysis of Co-STAR, an ancillary study of the STAR breast cancer prevention trial in which postmenopausal women at increased breast cancer risk were randomized to tamoxifen or raloxifene. Co-STAR enrolled nondemented participants ≥65 years old to compare treatment effects on cognition. The cognitive battery assessed global cognitive function (Modified Mini-Mental State Exam), and specific cognitive domains of verbal knowledge, verbal fluency, figural memory, verbal memory, attention and working memory, spatial ability, and fine motor speed. Adherence was defined by a ratio of actual time taking therapy per protocol ≥80% of expected time. Logistic regression was used to evaluate the association between cognitive test scores and adherence to therapy. The mean age of the 1,331 Co-STAR participants was 67.2 ± 4.3 years. Mean 3MS score was 95.1 (4.7) and 14% were nonadherent. In adjusted analyses, the odds of nonadherence were lower for those with better scores on verbal memory [OR (95% confidence interval): 0.75 (0.62-0.92)]. Larger relative deficits in verbal memory compared with verbal fluency were also associated with nonadherence [1.28 (1.08-1.51)]. Among nondemented older women, subtle differences in memory performance were associated with medication adherence. Differential performance across cognitive domains may help identify persons at greater risk for poor adherence.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Anticarcinogenic Agents / therapeutic use
  • Breast Neoplasms / prevention & control*
  • Cognition / physiology*
  • Cognition Disorders / complications*
  • Female
  • Humans
  • Logistic Models
  • Medication Adherence*
  • Middle Aged
  • Neuropsychological Tests
  • Postmenopause
  • Raloxifene Hydrochloride / therapeutic use*
  • Risk
  • Tamoxifen / therapeutic use*


  • Anticarcinogenic Agents
  • Tamoxifen
  • Raloxifene Hydrochloride