Research clarifies potential role of oestrogen in brain activity associated with memoryBMJ 1999; 318 doi: https://doi.org/10.1136/bmj.318.7190.1030c (Published 17 April 1999) Cite this as: BMJ 1999;318:1030
Research using functional magnetic resonance imaging has shown that giving standard doses of oestrogen to postmenopausal women increases activity in regions of the brain associated with memory (JAMA1999;281:1197-1202). These findings offer the best evidence yet that the hormone can affect the neural circuits involved in human memory and could help in treating Alzheimer's disease.
Researchers at Yale University School of Medicine in New Haven, Connecticut, examined brain activity in 46 women as they memorised and then recalled nonsense words or letters from a foreign alphabet. Brain activity was examined using functional magnetic resonance imaging, which tracks changing patterns of blood flow in the brain as mental activity stimulates different neural circuits. For three weeks before the test the women, who ranged in age from 33 to 61 and who had all undergone the menopause, were randomly allocated to treatment with either oestrogen or placebo. When the researchers compared the brain activation patterns of women who had taken oestrogen with those who had taken placebo they found that the response of the brain to memory tasks was faster when more oestrogen was present.
Study findings also suggested that oestrogen may have stimulated the women's brains to make the type of neural connections typically seen in younger people. “The results indicated that the neural circuitry in memory for mature individuals can be changed,” said Sally Shaywitz, professor of pediatrics at the University of Yale, and the study's lead author.
However, the researchers cautioned that although they observed increased brain activity in women who had been given oestrogen, there was no subsequent improvement in verbal or non-verbal memory tasks. Dr Shaywitz suggested that the lack of measurable evidence of an improvement in memory function was probably because the tasks in the study were simple and almost all were performed correctly. If a study participant was asked something that she did not know the scan would measure her effort rather than her memory function, Dr Shaywitz said.
Researchers believe, however, that the increased brain activity may indicate that there is an accompanying improvement in memory function. The effect of oestrogen on mental functions has always been controversial. Previous research has reported evidence that it may boost short term memory, improve reaction times, or counter depression in postmenopausal women; other research has found no link between oestrogen and intellectual abilities in older women.
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