Some women go through menopause earlier in life than other women because they have lost their reproductive ability prematurely or as a result of medical treatments or surgery such as ovariectomy, the removal of the ovaries. A new study, however, suggests that women who cease to menstruate before they reach 40 years old are likely to have poorer reaction times and increased risks for memory problems.

In the new study published in BJOG: An International Journal of Obstetrics and Gynaecology May 7, Joanne Ryan, from the Hospital La Colombiere in France, and colleagues, wanted to know if menopausal by or before the age of 40 can have long term effects on a woman's mental ability and whether this effect could be influenced by use of hormone treatment and the type of menopause so they conducted cognitive tests on 4,868 women who were over 65 years old.

Of these women, 7.6 percent had premature menopause, or menopausal before age 40, and 13 percent went through menopause when they were between 41 and 45 years old.

After their initial test at the start of the study, the women were again given cognitive tests after two, four and seven years. By comparing the results of these tests, the researchers found that the women who went through menopause before age 40, are least likely to do well in memory and verbal fluency tests. They also had 30 percent increased risk of showing decline in cognitive function and psychomotor speed over the course of the study period.

The researchers have likewise noted that use of hormone treatment apparently had benefits on a woman's later-life visual memory albeit it could have a negative effect on verbal fluency. Ryan and her colleagues have also observed that the type of menopause did not have an impact on the women's cognitive abilities.

"Both premature surgical menopause and premature ovarian failure were associated with long-term negative effects on cognitive function," the researchers wrote adding that women should consider the implications of early surgical menopause on their cognitive health. "These results suggest that the potential long-term effects on cognitive function should form part of the risk/benefit ratio when considering ovariectomy in younger women."