The rationale, design, and baseline characteristics of the Women's Health Initiative Memory Study of Younger Women (WHIMS-Y).

The Women's Health Initiative Memory Study-Younger (WHIMS-Y) was designed to assess the effect of prior random assignment to hormone therapy (HT) (conjugated equine estrogen (CEE) alone or CEE plus medroxyprogesterone acetate (MPA)) on global cognitive function in younger middle-aged women relative to placebo. WHIMS-Y was an ancillary study to the Women's Health Initiative (WHI) HT trial and enrolled 1361 women who were aged 50-55 years and postmenopausal at WHI enrollment. WHIMS-Y will examine whether an average of 5.4 years of HT during early menopause has longer term protective effects on global cognitive function and if these effects vary by regimen, time between menopause and study initiation, and prior use of HT. We present the study rationale and design. We describe enrollment, adherence to assigned WHI therapy, and compare risk factor characteristics of the WHIMS-Y cohort at the time of WHI enrollment to similar aged women in the WHI HT who did not enroll in WHIMS-Y. Challenges of WHIMS-Y include lower than expected and differential enrollment. Strengths of WHIMS-Y include balance in baseline risk factors between treatment groups, standardized and masked data collection, and high rates of retention and on-trial adherence and exposure. In addition, the telephone-administered cognitive battery showed adequate construct validity. WHIMS-Y provided an unprecedented chance to examine the hypothesis that HT may have protective effects on cognition in younger postmenopausal women aged 50-55 years. Integrated into the WHI, WHIMS-Y optimized the experience of WHI investigators to ensure high retention and excellent quality assurance across sites. This article is part of a Special Issue entitled Hormone Therapy.