Excessive memory decline or dementia affects an increasing number of women as they become older. The frequency of dementia doubles every 5 years beginning at age 60, making the discovery of ways to prevent or slow the disease imperative. Previous studies have indicated that changes in memory may be associated with the female hormonal decline that occurs after menopause, but more research is needed to establish the link between menopause and poorer memory function. It is believed that taking the female hormones estrogen and/or progesterone may help improve women's health by protecting against memory decline. This study will evaluate the effects of female hormone replacement therapy (HRT) on the development and progression of memory loss in older women enrolled in the Women's Health Initiative (WHI) study.

Diseases of the memory, including dementia and Alzheimer's disease, are a primary health concern of the aging population. In just the last 30 years, the number of Americans diagnosed with memory diseases has doubled. The beginning signs and symptoms of Alzheimer's and dementia include mild forgetfulness, confusion, and disorientation with time and place. As the diseases advance, people often experience difficulty in carrying out normal activities, recognizing family and friends, and eventually speaking and comprehending. Early identification and treatment for dementia and Alzheimer's may help prevent and slow the progression of symptoms, but the most beneficial means of treatment is still unknown. Previous studies have suggested a link between menopause and reduced memory function in women, possibly attributed to the dramatic decline in the levels of the female hormones estrogen and progesterone. HRT in postmenopausal women may help to curb memory loss and reduce risk of developing memory-related diseases. This study will evaluate the effects of female HRT on the development and progression of memory loss in older women enrolled in the WHI study.

Participants in this study will be drawn from the WHI study and will have previously been assigned to HRT with estrogen, HRT with estrogen plus progesterone, or placebo. During this study, participants will continue to take their assigned treatments from the WHI study.

Participation will last up to 6 years. All participants will undergo baseline memory and thinking tests, including a mood assessment and tasks measuring memory and other brain functions. Study staff will conduct a telephone interview with a close family member or friend. Some participants may additionally undergo a 45-minute interview with a clinician, a blood draw, and a computerized tomography (CT) scan. All participants will repeat the baseline memory and thinking tests once annually for 6 years, and some participants will repeat the interview, blood draw, and CT scan at these annual visits as well.

Inclusion Criteria:

• Enrolled in the Women's Health Initiative - Hormone Therapy Trial
• Aged 65 - 79 years of age at time of enrollment

This study will include participants from the hormone therapy trial of the WHI study.