First-Line Dementia Medication
For mild-to-moderate Alzheimer-type dementia, initiate treatment with a cholinesterase inhibitor: donepezil, galantamine, or rivastigmine. These are the established first-line agents endorsed by major clinical practice guidelines 1.
Choosing Among Cholinesterase Inhibitors
The three cholinesterase inhibitors are considered therapeutically equivalent in efficacy, so base your selection on tolerability, dosing convenience, and cost 1. The evidence is insufficient to demonstrate superiority of one agent over another 1.
Practical Selection Criteria:
- Donepezil: Most commonly prescribed; once-daily dosing; approved for mild-to-severe dementia; generally well-tolerated 2, 3
- Galantamine: Twice-daily dosing; approved for mild-to-moderate dementia 2
- Rivastigmine: Available as patch or oral formulation; patch may reduce GI side effects; approved for mild-to-moderate dementia 2
Avoid tacrine entirely due to severe hepatotoxicity and need for frequent monitoring, despite FDA approval 1.
When to Consider Memantine
Memantine is not first-line for mild-to-moderate Alzheimer's disease. Reserve memantine for:
- Moderate-to-severe Alzheimer's disease as monotherapy 2, 4, 3
- Moderate Alzheimer's disease in combination with a cholinesterase inhibitor 3
- Patients who cannot tolerate cholinesterase inhibitors
The 2020 Canadian guidelines confirm memantine is approved specifically for moderate-to-severe AD, not as initial therapy for mild disease 5.
Critical Implementation Points
Individualized Decision-Making
Do not prescribe these medications universally to every patient with dementia 1. The 2008 ACP/AAFP guidelines explicitly state the decision should be individualized because:
- Statistically significant improvements often do not reach clinically important thresholds (≥4 points on ADAS-cog, ≥3 points on MMSE) 1
- No reliable way exists to predict which patients will have clinically meaningful responses 1
- Many patients show statistical but not functional improvement
Monitoring and Duration
- Assess response within 3 months of initiating therapy 1
- Look for improvement, stabilization, or decreased rate of decline—not just cognitive scores but functional status and quality of life
- Continue therapy as long as decline prevention remains a meaningful goal 1
Major Contraindications to Avoid
Cholinesterase inhibitors and memantine are contraindicated in 1:
- Uncontrolled asthma
- Angle-closure glaucoma
- Sick sinus syndrome
- Left bundle-branch block
Common Adverse Effects
Cholinesterase inhibitors commonly cause 1:
- Nausea (most frequent)
- Diarrhea
- Dizziness
- Agitation
- Headache
Withdrawal rates due to adverse effects range 9-12% (versus 7-13% for placebo), indicating generally acceptable tolerability 1.
Evidence Quality and Limitations
The guideline recommendations carry a weak strength with moderate-quality evidence 1. This reflects that while cholinesterase inhibitors show statistically significant benefits in multiple trials, the clinical importance of these changes remains debatable. Most trials lasted less than one year, and head-to-head comparisons are limited 1.
The 2020 Canadian guidelines 5 and recent 2025 update 6 confirm cholinesterase inhibitors remain standard symptomatic therapy for mild-to-moderate dementia, with no fundamental changes to this treatment paradigm despite advances in disease-modifying therapies for early-stage disease.
When to Deprescribe
Consider discontinuing cholinesterase inhibitors or memantine when 5:
- Documented decline over 6 months despite treatment (without delirium or acute illness)
- No benefit ever observed during treatment
- Severe/end-stage dementia with dependence in most basic ADLs
- Intolerable side effects (confusion, dizziness, falls)
- Poor medication adherence
Taper gradually: reduce dose by 50% every 4 weeks to the starting dose, then discontinue after 4 additional weeks 5.