Solomon and colleagues gave gingko or a placebo to 130 normal adults over the age of 60. A number of neuropsychological tests of memory, concentration, and language use were conducted both before and after the 6-week trial. (The manufacturer claims that memory and cognitive enhancements will be felt after 4 weeks.) In addition, reports were collected from the subjects and their daily companions. There were no significant differences, or even trends toward improvement, on any measure.

According to the authors, U.S. gingko sales garnered some $240 million in 1997, and more than 5 million prescriptions for the supplement are written in Germany each year, primarily for dementia, cerebral decline, and vascular insufficiency. There have been a number of studies of gingko and cognitive effects in either healthy adults or dementia. Most have been short-term (2-8 weeks), and at best, the results have been spotty-in some cases gingko appeared to slightly raise tests scores in one area for one subgroup of patients at one testing interval, although reports by patients, physicians, and/or relatives have consistently indicated no noticeable enhancement in memory or cognitive status. The current results will do nothing to enhance this questionable efficacy record. -Hakon Heimer

Reference:Solomon PR, Adams FA, Silver A, Zimmer J, De Veaux R. Ginkgo for memory enhancement: A randomized controlled trial. JAMA. 21 Aug 2002;288(7):835-40. Abstract