While the average age at menopause is about 50 years old, premature menopause refers to menopause that occurs at or before the age of 40. Sometimes this due to surgically induced menopause, such as a bilateral ovariectomy, or “natural” menopause, which is the non-surgical loss of ovarian function, the researchers said.
Of the 4,868 women in the study, 79 percent reported natural menopause, while 10 percent reported surgical menopause and 11 percent reported menopause due to other causes, such as radiation or chemotherapy.
About 7.6 percent of the women had a premature menopause, while another 12.8 percent reported an early menopause (between the ages of 41 and 45).
More than one-fifth of the women used hormone treatment during menopause.
The researchers used cognitive tests and clinical dementia diagnosis at baseline and after two, four, and seven years to determine whether premature menopause had an effect on later-life cognitive function.
The study’s findings show that, in comparison to women who experienced menopause after the age of 50, those with a premature menopause had a more than 40 percent increased risk of poor performance on tasks assessing verbal fluency and visual memory.
Premature menopause was also associated with a 35 percent increased risk of decline in psychomotor speed, which is the coordination between the brain and the muscles that bring about movement. It also was associated with a decline in overall cognitive function over the study’s seven years.
However, there was no significant association with the risk of dementia, the researchers discovered.
The researchers did find that both premature ovarian failure and premature surgical menopause were associated with a more than twofold risk of poor verbal fluency. In terms of visual memory, premature ovarian failure was associated with a significantly increased risk of poor performance, and there was a similar trend for premature surgical menopause, the researchers report.
When the potential modifying effect of using hormone treatment at the time of premature menopause was examined, there was some evidence that it may be beneficial for visual memory, but it could increase the risk of poor verbal fluency, according to the researchers.
“Both premature surgical menopause and premature ovarian failure were associated with long-term negative effects on cognitive function, which are not entirely offset by menopausal hormone treatment,” said Dr. Joanne Ryan, a postdoctoral research fellow in neuropsychiatry at the Hospital La Colombiere in Montpellier, France.
“In terms of surgical menopause, our results suggest that the potential long-term effects on cognitive function should form part of the decision-making process when considering ovariectomy in younger women.”