Dietary herbal supplements, such as black cohosh, have shown mixed and inconclusive results in placebo-controlled studies of menopausal symptoms.

Researchers from Northwestern University, in Chicago, Illinois compared black cohosh and red clover to hormone therapy for their effects on cognition (reasoning).

First, the details.

• 66 midlife women with at least 35 weekly hot flashes were randomly assigned to a treatment group for 12 months.
  • Red clover (a phytoestrogen) 120 mg daily
  • Black cohosh 128 mg daily
  • 0.625 mg conjugated equine estrogens + 2.5 mg medroxyprogesterone acetate (a Prempro type combination hormone treatment)
  • Placebo
• Neither the researchers nor patients knew the treatment given — double blind.
• Verbal memory and other cognitive measures before and during the 12th treatment month were recorded.
• 19 women carried ambulatory skin conductance monitors (example here).

And, the results.

• Neither herbal changed verbal memory and other cognitive measures.
• Compared to placebo, combined hormone therapy led to a significantly greater decline in verbal learning after adjusting for the change in vasomotor symptoms (hot flashes).
• Neither herbal showed changed verbal memory vs placebo.
• Combined hormone therapy lead to a decrease in immediate digit recall (repeating a list of numbers after hearing them and an improvement in letter fluency (state as many words as possible beginning with a certain letter in 1 minute).
• Only hormone therapy significantly reduced hot flashes.

The bottom line?
The researchers concluded, “Results indicate that a red clover (phytoestrogen) supplement or black cohosh has no effects on cognitive function. [Combined hormone therapy] reduces objective hot flashes but worsens some aspects of verbal memory.”

The lack of effect of red clover reported is supported by an earlier study here.

A PubMed search revealed no other studies of the effect of black cohosh on cognition during menopause.

7/12/09 19:20 JR