Which drug is a cholinesterase inhibitor used to treat Alzheimer's disease?

• A. Donepezil
• B. Memantine
• C. Levodopa
• D. Quetiapine

Answer: (A)

Cholinesterase inhibitors increase acetylcholine in the brain by blocking acetylcholinesterase, boosting cholinergic transmission to help mitigate cognitive symptoms in Alzheimer's disease. This mechanism directly targets the neurotransmitter system involved in memory and learning, which is why this class is used as symptomatic treatment for Alzheimer's. Donepezil is a cholinesterase inhibitor approved for Alzheimer’s disease, making it the best choice for this question.

Memantine works differently, as an NMDA receptor antagonist used for moderate to severe Alzheimer’s when cholinesterase inhibitors are not sufficient. Levodopa is a dopamine precursor used for Parkinson’s disease, not Alzheimer’s. Quetiapine is an antipsychotic used for mood disorders and agitation in dementia, but it does not treat Alzheimer’s cognitive symptoms through cholinesterase inhibition.