Donepezil is mainly used to treat symptoms of Alzheimer's Disease, where it can help improve memory and thinking for some time, but it may also provide modest benefit in certain cases of dementia caused by strokes (called vascular dementia or post-CVA dementia), although the effect is usually less predictable and not as strong as in Alzheimer's disease. It does not cure dementia or stop disease progression, but may help with symptoms in selected patients, so doctors may try it on a case-by-case basis depending on the type and severity of dementia. Regular follow-up is important to assess whether it is helping and to monitor for side effects like nausea or sleep disturbances.