New research suggests that removing the ovaries, especially in the case of young women, significantly increases the risk for cognitive problems later in life. Researchers at the Mayo Clinic showed that the surgically removal of a woman's ovaries raises the risk of developing dementia. Dr. Walter Rocca, a professor of neurology and epidemiology and lead author of the study, advised women to be cautious when deciding to undergo the procedure, estrogen possibly being "the root of the problem". Estrogen-replacement therapy might help avoid these cognitive problems. . Rocca's team focused on women who no longer had ovaries, a major source of estrogen. 300,000 women undergo annually ovary-removal surgery or ovariectomy, because either they fear cancer, or they have it. Researchers investigated medical records of 1,209 women who had both ovaries removed and 1,302 women who had only one removed from 1950 to 1987 and tested their cognitive ability. Women who had their ovaries removed were 1.2-1.6 times more likely to suffer from dementia. The risk is higher for women who remove both of their ovaries before 46 years and for those who had one ovary removed before age 38. "We can't be sure whether it's the estrogen itself that's involved, or rather that women who have the surgery may be already genetically predisposed to having estrogen-related problems," Rocca said. Researchers also suspect that some women have a genetic predisposition that "dictates" the need for ovary removal, and also causes a rapid development of dementia.