Based on this finding, the researchers believe there's no reason to use hormone replacement therapy to boost mental well-being after periods stop, Newsmax reports.

However, while estrogen wasn't tied to any mental benefits, the study found that another hormone -- progesterone -- might affect thinking ability in younger women.

The sex hormones estrogen and progesterone typically decline in a woman's 30s and 40s, eventually resulting in menopause and an end to fertility. The average age of menopause is about 50.

The benefits and harms of hormone replacement therapy have been the subject of much debate. Previous studies have linked use of synthetic hormones after menopause with increased risk for heart disease, stroke, blood clots and breast cancer.

Dr. Jennifer Wu, an obstetrician/gynecologist at Lenox Hill Hospital in New York City, said that after menopause "a lot of women think that lack of estrogen will lead to mental decline."

"Trying to maintain mental abilities is not a reason to take on all the risks of hormone replacement therapy," she said.

Some scientists theorized that estrogen's effect on thinking might depend on how soon after menopause hormone levels were boosted. This led the researchers of this study to divide the participants into two groups -- women within six years of menopause and those more than 10 years beyond menopause.

They found that the relation between blood levels of estrogen and memory or planning skills is the same in younger postmenopausal women as in older postmenopausal women.