A research study conducted by Dr. Jesus Lovera, Assistant Professor of Neurology at LSU Health Sciences Center New Orleans, and colleagues has found that the herbal supplement Ginkgo biloba does not improve cognitive function in patients with Multiple Sclerosis (MS.) Cognitive impairment affects 40-60% of people with MS, most commonly affecting their processing speed, memory, and executive skills.

The research findings were published online ahead of print in Neurology on Sept. 5, 2012.

This study followed up on a promising earlier small study by Dr. Lovera and his colleagues that had shown improvement in cognitive function with Ginkgo biloba in people with MS. Some studies have also shown improvement after treatment with Ginkgo biloba in people with Alzheimer's disease.

"Ginkgo biloba supplements are frequently used by people with MS. Ginkgo appeared beneficial in a prior small pilot study we had done," said Dr. Jesus Lovera, a neurologist at LSU Health Sciences Center New Orleans who specializes in MS.

The researchers wanted to conduct a larger more robust study to determine the validity of the preliminary results. One hundred twenty people with MS were randomized to either the group treated with 120 mg of Ginkgo biloba twice a day, or to the group taking matching placebo tablets. Participants were treated for 12 weeks and then underwent a battery of cognitive tests. Participants and their families also answered standardized questionnaires about their cognitive function and social integration. The tests found that there were no statistically significant improvements in cognitive function between the two groups.

"Unfortunately we did not see any improvement with Ginkgo in this new study," notes Dr. Lovera. "Several drugs such as Namenda and Aricept that work for people with Alzheimer's have been tested without success in people with MS. Unfortunately now Ginkgo is added to the list of therapies thought to be effective in Alzheimer's disease that failed to improve cognitive performance in MS."

While the study provides solid evidence, the researchers noted several limitations. Participants were treated for only 12 weeks and perhaps that was not long enough to modify the disease. The median duration of MS was 20 years, and it is possible that Ginkgo may improve cognitive function earlier in the MS disease process. It is also possible that there could have been a positive effect in participants with more severe impairments than those in this study. Additional functional assessments that measure performance in real-life situations may also have detected an effect that was missed by limiting the outcome measures to cognitive tests and questionnaires.

According to the National Institutes of Health, Multiple Sclerosis is an unpredictable disease of the central nervous system, that can range from relatively benign to somewhat disabling to devastating, as communication between the brain and other parts of the body is disrupted. Many investigators believe MS to be an autoimmune disease -- one in which the body, through its immune system, launches a defensive attack against its own tissues. In the case of MS, it is the nerve-insulating myelin that comes under assault. Such assaults may be linked to an unknown environmental trigger, perhaps a virus.

According to the Multiple Sclerosis Association of America, MS is the most common neurological disorder diagnosed in young adults.

Approximately 400,000 individuals have been diagnosed with MS in the United States and as many as two and a half million worldwide, with an estimated 10,000 new cases diagnosed in the United States annually. Most people with MS experience their first symptoms and are diagnosed between the ages of 15 and 50.

The team also included researchers from the Portland VA Medical Center, Puget Sound Health Care System, University of Washington, and Oregon Health & Science University. The US Department of Veterans Affairs supported the research.