Alzheimer's Disease Medications

Alzheimer's drugs don't cure or halt disease progression — they temporarily slow cognitive decline. Knowing which neurotransmitter each class targets determines when you use it and what side effects to expect.

Two drug classes treat Alzheimer's disease, each targeting a different neurotransmitter system. Cholinesterase inhibitors — donepezil, rivastigmine, galantamine — block the enzyme that breaks down acetylcholine, boosting levels of this memory-related neurotransmitter in the brain. They are first-line for mild-to-moderate Alzheimer's; donepezil is also FDA-approved for severe disease. Because they increase acetylcholine systemically, expect cholinergic side effects: nausea, diarrhea, bradycardia, and weight loss. Always check the heart rate before administration — bradycardia is a real risk, especially if the client is on beta-blockers. Donepezil is given at bedtime to minimize GI effects. Memantine works differently: it blocks excess glutamate at NMDA receptors, preventing excitotoxic neuronal damage. It is approved for moderate-to-severe Alzheimer's and can be combined with a cholinesterase inhibitor. Memantine does not cause cholinergic side effects; watch instead for dizziness, headache, and constipation. Neither class reverses damage already done — the goal is to maintain current function as long as possible.

Key Distinctions

Don't confuse cholinesterase inhibitors (boost acetylcholine, used early) with memantine (blocks glutamate, used later) — they have completely different mechanisms and side effect profiles. Students mix up donepezil's bradycardia risk with memantine's relatively benign cardiac profile. Cholinesterase inhibitors increase cholinergic activity everywhere, not just the brain — that's why GI and cardiac effects occur.

Clinical Pearl

Cholinesterase inhibitors make more acetylcholine; memantine calms down glutamate. Think: 'early = ACh boost, late = glutamate block.'