The clinical trial from which plasma estradiol levels were assayed was a 1-year study in women with AD treated with conjugated equine estrogens and no progestin. One hundred twenty women who underwent hysterectomy (to allow for exposure to estrogen therapy without the need for a progestin) were recruited into a multicenter clinical trial comparing the dose effects of placebo (n = 39), 0.625 mg/d of Premarin (n = 42), and 1.25 mg/d of Premarin (n = 39). Informed consent was obtained from the patient or the patient's caregiver acting as proxy for the patient, according to local internal review board guidelines. The study participants had baseline Mini-Mental State Examination (MMSE) scores between 12 and 2811 and, therefore, represented subjects with mild to moderate AD. The study medication was randomized and double-blinded with 12 months of estrogen exposure followed by a 3-month, single-blind washout period. The primary outcome measure was the Alzheimer's Disease Cooperative Study Clinical Global Impression of Change.12 In addition, a range of secondary outcome measures were obtained including the MMSE, Alzheimer's Disease Assessment Scale—Cognitive (ADAS-Cog),13 Clinical Dementia Rating (CDR) Scale,14 Hamilton Depression Rating Scale,15 Emotional Face Recognition Test (Elizabeth Koss, PhD, written communication, June 3, 1998), New Dot Test,16 Letter Cancellation test,17 Trail Making Test,18 Digit Symbol Test,19 Category Fluency test,20 Letter Fluency test,21 Grooved Pegboard Test,22 Finger Tapping Test,23 Blessed Dementia Rating Scale (activities of daily living),24 and the dependent scale.25 The relationship between a change in hormone levels and the change in 7 selected neuropsychological measures was explored in this analysis.