The menopause may weaken a woman's ability to learn compared to other stages of her life, research has claimed.
Researchers found processing speed improved with repeated testing during premenopause, early perimenopause and postmenopause, but that scores during late perimenopause did not show the same degree of improvement.
Developments in processing speed during late perimenopause were only 28 per cent as large as improvements observed in premenopause.
There were also differences in verbal memory performance through the different stages.
The authors said the results suggest women do not learn as well during the early and late perimenopause as they do during other transition stages.
Gail Greendale, from the University of California, commented: "These ? results concur with prior self-reported memory difficulties - 60 per cent of women state that they have memory problems during the menopause transition.
"The good news is that the effect of perimenopause on learning seems to be temporary. Our study found that the amount of learning improved back to premenopausal levels during the postmenopausal stage."
The study also found that taking oestrogen or progesterone hormones before menopause helped verbal memory and processing speed.