Chester J. Zelasko, Ph.D. |
August 27, 2002
Once again, the
Newsletter addresses science by headlines--this time the herb ginkgo biloba
has been in the news. Researchers tested the effects of a specific brand of
ginkgo biloba on the potential for enhancing the memories of healthy elderly
persons (1). The researchers reported that ginkgo was ineffective in
enhancing the memories of the healthy subjects when used for six weeks.
There are several things that should be noted about this study:
The best conclusion that anyone could reach from this single study was that
people who are not experiencing any memory problems will not see any
improvement in memory when they take the ginkgo product used in the study.
- The researchers selected a group of older persons who were at or
above the norm for their age in their ability to learn based on the
Mini-Mental State Examination (MMSE). That means they were exactly where
they were supposed to be for their age and education. While moderately
interesting, it would seem more appropriate to examine the effects of
ginkgo on people who scored low on the MMSE and have memory problems.
- The data show no significant differences between the experimental
group and placebo group in any variable tested--absolutely none. That
seems unlikely. With the level of significance set at .05, at least one
of the variables tested should have been significantly different due to
- One of the attributes of ginkgo is that it increases blood flow. The
researchers did not test any physiological variables. Granted, that
would have been expensive and might cause subjects to drop out, but
those tests would have provided valuable information.
- They did not ask the subjects how they felt about their memory. It
seems likely that some people would have felt better whether taking the
placebo or the ginkgo. This would appear to be a question psychologists
would ask, but they didn't.
- Finally, it took four years for the researchers to publish this
paper. When there are significant findings, no one waits--they publish
results first and ask questions later. That didn't happen, and one
wonders why they waited so long.
What the current study does is provide some information and raises
questions. Perhaps to improve memory in this population would have taken
longer because they had no memory problems or the dose would need to be
higher. That's left for future studies to determine.
Ginkgo biloba is one of the most researched herbs sold as a food supplement.
It has been shown to have benefits for improving attention span and
improving blood flow to the brain and muscles (2-3). It has also proven to
be a safe supplement--although all herbs should be stopped 1-2 weeks before
any elective surgery. As part of a healthy lifestyle that includes eating
right, exercising regularly, and managing stress, supplementing with ginkgo
biloba may give you an edge to help you cope with today's world.
- Paul R, et al. Ginkgo for Memory Enhancement: A Randomized
Controlled Trial. JAMA. 2002. 288:835-840.
- Kennedy DO, et al. The dose-dependent cognitive effects of acute
administration of ginkgo biloba to healthy young volunteers.
Psychopharmacology (Berl) 2000. 151(4):416-23.
- Peters H, et al. Demonstration of the efficacy of ginkgo biloba
special extract EGb 761 on intermittent claudication--a
placebo-controlled, double-blind multicenter trial. Vasa 1998.