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Before and after the 12 months, participants will complete a 1.5-hour battery of paper-and-pencil tests assessing memory, attention and concentration and mood.

Previous research has shown that age and hormones affect performance on many of these tests.

Women in the study will have the option to undergo brain scans before and after the treatment period.

"The goal of the scans is to pinpoint areas in the brain where different therapies may be acting to influence memory," Maki said.

"Interestingly, menopause per se has little influence on cognitive function in midlife women, but menopausal symptoms do," Maki said.

"That is, perimenopausal women who complain of sleep disturbances, depression and irritability perform worse on cognitive tests than women who have fewer such symptoms, suggesting that therapies to enhance mood and sleep may also help improve cognitive function." According to Maki, black cohosh, a wildfower native to forests in North America, has been shown in preliminary studies to bind to serotonin receptors, as antidepressant medications do.

That action could possibly help cognition, but to date, no studies have tested the effects of black cohosh on memory in midlife women.

Red clover, a small perennial herb native to Europe, Central Asia and northern Africa, contains phytoestrogens, naturally occurring compoun...