Estrogens and Cognition
In most animal species there are two sexes, living their lives in different hormonal milieus. These different hormonal milieus have been shown to affect the brain across the lifespan, having their effects on everything from reproduction to emotion to cognition. The main question we will be focusing on for the next five years is: How does one class of these hormones, estrogens, affect cognition in women? To understand more about how estrogens mediate cognition, we will study cognitive performance in women who have had prophylactic salpingo-oophorectomy or, removal of their ovaries and fallopian tubes. This will assure that the only available circulating estrogens will be from body tissues other than reproductive organs. This will provide us with three possible conditions under which to test cognitive performance: very little estrogen, hormone replacement, and inhibition of remaining estrogens by Tamoxifen. Performance under these conditions will be compared to the performance of age-matched controls. We will ask three basic questions: 1) Does estrogen status affect attentional control (i.e., the ability to multitask)?; 2) Are there changes in memory systems that occur over time and become exacerbated in a state of low estrogen?; 3) Why are some cognitive changes that occur in the absence of estrogen observable only at the neuronal level in functional imaging but not behaviorally and when do they “convert” to behavior? For all these experiments, we will measure amounts of circulating estrogens that are theoretically available to the brain as well as ascertain the genetic status for a gene that confers a risk factor for cognitive decline in order to better understand how hormones and genes interact to affect important aspects of cognition.