Donepezil is a drug which is thought to discourage the breakdown of acetylcholine, which is a neurotransmitter in the brain that is important to how memory functions. Acetylcholine is lacking in people with Alzheimer's disease (AD). The drug donepezil has been reported to have benefits for people with mild to moderate Alzheimer's disease who do not have Down syndrome. However, people with DS tend to present with AD at a much younger age than the general population as well as being physically different in terms of size, metabolism and heart rate, and may therefore have different requirements.
This review identified one randomised controlled trial of donepezil in people with Down syndrome. This shows, at best, a modest, non statistically significant trend in favour of people with Down syndrome and Alzheimer's dementia who are able to tolerate donepezil. The trial was of good quality, but small. It is important to note that people with Down syndrome may often have other conditions which mean that the drug is not suitable for all. Further research is needed.