Donepezil is a drug used in the treatment of Alzheimer's disease. It has been studied as a treatment for impaired memory in people with cognitive symptoms due to multiple sclerosis.
A small study followed 69 people with MS taking either donepezil or a placebo for 24 weeks. It found that twice as many people in the treatment group reported memory improvement (65.7%) than those on placebo (32.4%). Health professionals also reported that more people in the treatment group showed improved cognitive symptoms. However, a larger study involving 120 people with MS showed no difference in improving memory between donepezil and placebo. More gastrointestinal side effects are seen with this type of medication than with a placebo.
A group in Iran have also looked at the effects of donepezil on cognitive impairment, quality of life and depression in MS. 100 patients with MS were divided into two groups, half took 10mg donepezil daily for three months whilst the other half received placebo. They concluded that donepezil could effectively improve cognitive issues and also had a positive effect on quality of life and depression.
However, a second study by the same group compared the benefits of donepezil against cognitive rehabilitation on memory, attention, quality of life and depression in MS. Although they found that both donepezil and cognitive rehabilitation had a positive effect on all four areas evaluated, cognitive rehabilitation was shown to be a more effective treatment than donepezil.
Because there have been limited trials of donepezil in MS and the results have been mixed, the current evidence of the efficacy of donepezil on cognitive function in people with MS is unclear.