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| |  Estrogen Affects Brain Activity In Postmenopausal Women CHICAGO, IL. -- April 7, 1999 -- Therapeutic doses of estrogen affect brain activity in postmenopausal women performing memory tasks; however, estrogen did not affect verbal and nonverbal memory tasks, according to a clinical investigation in the April 7 issue of The Journal of the American Medical Association (JAMA). Sally E. Shaywitz, M.D., from Yale University, New Haven, Conn., and colleagues used functional magnetic resonance imaging to study the influence of estrogen on postmenopausal women’s brain activation patterns during tasks involving verbal and nonverbal working memory. Forty-six postmenopausal women (aged 33 to 61 years) were treated with either estrogen or placebo in a randomized, double-blind, placebo-controlled, crossover trial from 1996 through 1998. "The results of this study indicate that estrogen in a traditionally prescribed therapeutic dose produces significant alterations in brain activation patterns [in specific brain regions] in postmenopausal women as they perform working memory tasks," the researchers write. "These data suggest that it may be possible to affect functional brain organization in older women; these alterations in brain activation patterns in subjects taking estrogen suggest functional plasticity of memory systems in mature women." The authors surmise that estrogen may have a positive influence on language and memory through its actions on phonologic (speech and sound) mechanisms and their research supports the hypothesis that estrogen mediates the short-term storage of phonologic material. They speculate that estrogen’s effects may be mediated through its actions on neural sites serving phonologically coded materials. The research also indicates that the effects of estrogen are not limited to verbal memory, but also effect visual memory tasks. According to the authors, the average woman spends at least half of her adult life with decreased levels of estrogen. Decisions concerning hormone replacement therapy represent major concerns for postmenopausal women. Declining estrogen levels characterize menopause with effects on a range of systems including, in addition to the reproductive system, the cardiovascular and skeletal systems. Results of studies examining the influence of estrogen on the cognitive function of postmenopausal women are far from consistent. "This current study demonstrates that estrogen alters brain activation patterns in postmenopausal women and its corollary that functional brain organization in mature women (and, we assume, men) is neither fixed nor immutable," the researchers explain. "These changes in brain activation patterns are observed in specific brain regions associated with the sorts of memory function that are called on frequently during any given day (for example, trying to remember a telephone number that had just been looked up); and appear to reinstate patterns typically observed in younger, but not older, subjects as they perform memory tasks. "While we believe the changes in brain organization should predict accompanying improvements in performance of memory tasks, we caution that in this study we did not observe such changes during the study period," the researchers continue. "However, these data suggest that estrogen affects brain organization in postmenopausal women. In addition, functional imaging may provide a new tool to detect these effects of estrogen. The results are encouraging and suggest that the use of functional imaging together with protocols examining, for example, different dosages, treatment lengths and washout periods, may provide a new means to explore the effects of estrogen on cognitive function in postmenopausal women." This study was supported by grants from the National Institute of Child Health and Human Development, Bethesda, Md.
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