News Release

Loss of estrogen affects different cognitive abilities, says new study, and may have implications for hormonal replacement therapies in humans

Peer-Reviewed Publication

American Psychological Association

Lack of estrogen decreases visual memory but improves spatial memory

WASHINGTON -- Every woman will face the loss of estrogen at some point in her lifetime and will suffer negative health consequences -- changes in memory, depression, hot flushes and brittle bones. But in a new study of rhesus monkeys, one positive result was found. Those monkeys without functioning ovaries performed better on spatial memory tasks than monkeys with intact ovaries. These findings are reported in the June issue of Behavioral Neuroscience, published by the American Psychological Association (APA).

To find out the effects of prolonged deprivation of estrogen on cognitive functions in aged female rhesus monkeys, lead author Agnes Lacreuse, Ph.D., of Emory University and colleagues compared the performance of six 19-27 year old long-term ovariectomized female rhesus monkeys with aged-matched female monkeys with intact ovaries on object recognition memory, object and spatial memory and decision making tasks. Also to determine whether long-term loss of estrogen exacerbates normal age-related cognitive decline, the aged females were also compared to young female (4-7 year old) monkeys with intact ovaries.

The ovariectomized female monkeys performed poorly on the object recognition tasks but performed better on a spatial memory task. These monkeys actually performed as well as the young monkeys with intact ovaries on one of the spatial tasks. This task required the monkeys to identify the new position of a stimulus among an increasing set of identical, serially presented stimuli.

"These results suggest," says Dr. Lacreuse, "that the absence of estrogen in aged female rhesus monkeys may protect against normal age-related decline in certain aspects of spatial memory." Other studies that used women and female rodents also found that estrogen may have deleterious effects on spatial performance. High estrogen levels during the menstrual cycle have been associated with impaired spatial performance in young women.

"We may speculate that the lack of estrogen in the monkeys without ovaries did help in preventing age-related decline in spatial memory by affecting hippocampal organization," said the authors. "This may generalize to human females and suggest that prolonged absence of the ovaries and their secretions may prevent or lessen age-related decline in certain aspects of spatial memory.

"These results may have important implications for the design of hormonal replacement therapies for postmenopausal women," said Dr. Lacreuse. "Future research should examine whether estrogen deficiency benefits some aspects of spatial cognition and whether estrogen treatments can reverse some or all of the influences of removing the ovaries."

"Rhesus monkeys were used to test whether estrogen deficiency was related to all cognitive decline and how this might transfer to human females," said the authors. "We used rhesus monkeys because they share numerous cognitive and physiological characteristics with humans. First, the menstrual cycle of the female rhesus monkey is very similar to that of the woman. Second, aged female rhesus monkeys experience menopause. Finally, rhesus monkeys are capable of complex cognitive behaviors, such as short-term memory and spatial ability."

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Article: "Cognitive Function in Aged Ovariectomized Female Rhesus Monkeys," Agnes Lacreuse, Ph.D., and James G. Herndon, Ph.D., Emory University; Mark B. Moss, Ph.D., Boston University School of Medicine, Behavioral Neuroscience, Vol. 114, No. 3.

Full text of the article is available from the APA Public Affairs Office or at http://www.apa.org/journals/bne.html after June 14.

Agnes Lacreuse, Ph.D., can be reached by telephone at 404-727-2417 or by email at alacreu@rmy.emory.edu

The American Psychological Association (APA), in Washington, DC, is the largest scientific and professional organization representing psychology in the United States and is the world's largest association of psychologists. APA's membership includes more than 159,000 researchers, educators, clinicians, consultants and students. Through its divisions in 53 subfields of psychology and affiliations with 59 state, territorial and Canadian provincial associations, APA works to advance psychology as a science, as a profession and as a means of promoting human welfare.



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