June 17, 2008 Women in midlife underreport the number of hot flashes that they experience by more than 40 percent, and these hot flashes are linked to poor verbal memory, according to a study by researchers at the University of Illinois at Chicago.
The study is published online and will appear in the September/October issue of the journal Menopause.
It is the first study to explore the relationship between objectively measured hot flashes and memory performance.
Memory complaints are common at midlife, and previous research indicates that about 40 percent of midlife women report forgetfulness.
A number of studies have looked at the relationship between menopausal symptoms (vasomotor symptoms, hot flashes and sleep disturbances that accompany hot flashes) and memory complaints and found no relationship between subjective, or self-reported, hot flashes and objective performance on memory tests in women.
These findings have left many to assume that there is no relationship between menopausal symptoms and memory dysfunction in women, said Maki.
"The problem is that the physiology of hot flashes and the science of hot flashes is more complex than we previously understood," she said.
The researchers enrolled 29 midlife women with moderate to severe hot flashes in an observational study. The women wore monitors that measured changes in skin conductance during a hot flash. Both subjective and objective hot flashes were recorded during a 24-hour period. The average number of objective hot flashes was 19.5 per day.
Maki and colleagues also objectively measured memory performance -- the recollection of words, names, word pairs, paragraphs and stories -- using standard neuropsychological tests.
"When we looked at the relationship between the hot flashes that the women truly had -- that is, the hot flashes that the monitor picked up -- and memory performance on the cognitive tests, we found a very strong relationship. So, the more true hot flashes a woman had, the worse her memory performance," said Maki.
"In other words, the hot flash-memory relationship is not all in a woman's head. It's actually a physiological relationship that you can pick up on, if you measure hot flashes objectively with a monitor."
When the researchers looked at the relationship between hot flashes women thought they had -- their subjective hot flashes -- there was no relationship with memory performance.
Maki and colleagues also observed a relationship between the total number of hours slept and memory performance the next day.
"The total number of hours slept predicted worse memory performance, but also the total number of hot flashes during the night when a woman was sleeping predicted memory dysfunction," Maki said. "So, the two together worsen memory in women the next day."
The study suggests that if women are treated for their vasomotor symptoms it may improve memory function in women with hot flashes, said Maki.
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