Donepezil, a drug used to treat Alzheimer’s disease, seems to improve the memory of people with multiple sclerosis (MS), according to a report in the journal Neurology.

MS is caused by the loss of myelin, the insulating sleeve around the brain’s neurons, while the underlying problem in Alzheimer’s disease seems to be a loss of the signaling chemical acetylcholine in so-called cholinergic nerves - two different processes. However, the researchers believe there may be a link.

“MS is not known to result in the reduction of acetylcholine,” Dr. Lauren Krupp, from the State University of New York at Stony Brook, explained in a statement. “But evidence suggests that there is a decrease in cholinergic activity, likely resulting from the disruption of cholinergic pathways by the demyelination and axonal damage to the nerves that occurs in MS.”

In their study, Krupp’s team used standard neuro-psychological tests to assess the effects of donepezil in 69 MS patients with mental impairment. The participants were given donepezil or an inactive placebo drug for 24 weeks.

Donepezil-treated patients showed a significant improvement in memory performance compared with those given placebo. By contrast, the drug was not linked to improvements in other aspects of mental functioning.

Treatment with donepezil appeared safe and was not associated with any serious side effects. However, patients treated with the drug were more likely to report unusual dreams than those on the placebo.

The results have “set the gold standard for the next generation of cognitive enhancer trials in MS,” Dr. P. Murali Doraiswamy, from Duke University in Durham, North Carolina, and Dr. Stephen M. Rao, from the Medical College of Wisconsin in Milwaukee, note in a related editorial.

Still, the editorialists note that many real-world questions remain to be unanswered, such as “How long should we treat? How do we tell if the drug is no longer working? Are benefits lost once the drug is stopped? Are there withdrawal effects? Are there long-term risks? Is treatment cost-effective?”

SOURCE: Neurology, November 9, 2004.