BAKERSFIELD, Calif. -- Researchers studied the verbal memory, working memory and brain processing speed of over 2,000 women at four different points before and during their transition to menopause.

Women showed the biggest change on learning tests during the late perimenopausal stage -- the period just before menopause.

The change was subtle. Subjects exhibited a lack of improvement over time rather than an overt decline.

Women's cognitive abilities rebounded to their premenopausal levels following the onset of menopause, suggesting that the effects are limited.

Researchers also found that women taking hormones before menopause slightly improved their verbal memory and information processing speed by 4 to 6 percent.

However, women taking hormone replacement therapy after menopause did not get this same benefit. In fact, current hormone use among postmenopausal women caused slightly slower processing speeds and worse verbal memory compared to their premenopausal cognitive performance.