When is the best time in a woman's reproductive history to start hormone therapy? How does estrogen therapy affect a woman's cognition and mood? What is the most beneficial form of estrogen?

These are just a few important questions that researchers at the University of Wisconsin School of Medicine and Public Health hope to answer in a federally funded nationwide study, the first of its kind, on the effects of estrogen therapy with perimenopausal women.

Led by Sanjay Asthana, head of the UW Section of Geriatrics and Gerontology and director of the Geriatric Research, Education and Clinical Center, the study will be the first in the world to address the most significant questions remaining about the use of hormone therapy in women.

The study, dubbed "KEEPS" (the Kronos Early Estrogen Prevention Study), will evaluate the efficacy of four years of hormone therapy on measures of cognition and mood in 720 healthy perimenopausal women at…