(NaturalNews) Women who have their ovaries surgically removed before menopause experience earlier and more severe cognitive decline, according to a study conducted by researchers from Harvard Medical School and Brigham and Women's Hospital, and due to be presented at the 65th Annual Meeting of the American Academy of Neurology in San Diego.
The researchers studied 1,837 postmenopausal women between the ages of 53 and 100 who were taking part in the Memory and Aging Project at Rush University Medical Center in Chicago. The researchers recorded the age at which women began menstruating, how many years they had menstruated, whether they used hormone replacement therapy and for how long, and whether they had undergone natural or surgical menopause.
"Surgical menopause" refers to the surgical removal of both ovaries before the onset of natural menopause, and is commonly performed along with hysterectomies. One-third of the women in the study had undergone this procedure.
The researchers found that the earlier a woman underwent surgical menopause, the faster she experienced a decline in overall thinking abilities and memory, particularly memory relating to time and place and long-term memory relating to ideas and concepts. No such association was seen between cognitive decline and the onset of natural menopause.
In addition, the brains of women who underwent surgical menopause at a younger age had significantly more of the plaques associated with Alzheimer's disease than those of women who had undergone the procedure later in life. Younger age of surgical menopause was not associated with overall risk of Alzheimer's disease, however.
Sudden drop in hormone levels
Researchers have known for quite some time that many women report short-term cognitive problems following menopause, both natural and surgical. A recent study, conducted by researchers from the University of Rochester and published in the journal Menopause, found that women between the ages of 40 and 60 who were in their first year after menopause scored significantly lower on tests of motor function, verbal learning, verbal memory, working memory and attention than pre-menopausal women. The effects were largest for verbal learning and memory.
The researchers believe that this effect is caused by a sudden drop in the levels of estrogen, which plays a critical role in cognition and memory. This hypothesis is supported by the fact that the researchers in the surgical menopause study found that women who had undergone hormone replacement therapy had a slower rate of cognitive decline.
"In the months after a woman has her last period, hormonal changes are most abrupt," said Pauline Maki, lead researcher of the Rochester study.
In the case of natural menopause, cognitive changes are temporary, and do not appear to be linked to the risk of dementia. According to the new study, the changes associated with surgical menopause are more long-term.
Due to the severe health risks associated with hormone replacement therapy; however, the researchers did not recommend it as a treatment for these symptoms.
"At this time, there's no indication to use hormone replacement therapy for the sole treatment of memory problems in natural or surgical menopause," Maki said.