Alzheimer's Drugs: How Should Families Weigh Treatment?

How do Alzheimer's medicines differ, and who qualifies?

Harvard Health's guide to Alzheimer's treatment and caregiving highlights a central family concern: how medical treatment fits into everyday care. Its educational coverage provides context for evaluating medicines, rather than announcing a new clinical trial. The practical starting point is understanding which treatment goal applies to the person being assessed. [Harvard Health's treatment and caregiving guide](https://www.health.harvard.edu/promotions/harvard-health-publications/alzheimers-disease-a-guide-to-coping-treatment-and-caregiving).

Cholinesterase inhibitors, including donepezil, rivastigmine and galantamine, support chemical signaling involved in memory and thinking. Memantine works through a different signaling pathway and is used for moderate to severe Alzheimer's disease. These medicines can help manage symptoms, although they do not cure the underlying illness. Selection depends on disease stage, tolerability and other health conditions. [National Institute on Aging treatment overview](https://www.nia.nih.gov/health/alzheimers-treatment/how-alzheimers-disease-treated).

Amyloid-targeting antibodies such as lecanemab and donanemab have a different purpose: slowing disease progression. Treatment begins in people with mild cognitive impairment or mild dementia due to Alzheimer's, with evidence of amyloid pathology. A diagnosis of forgetfulness alone does not establish eligibility. Donanemab's FDA approval was based on patients with early symptomatic disease and confirmed amyloid, so its findings should not be extended to advanced dementia or unrelated causes of memory loss. [FDA assessment of donanemab](https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-treatment-adults-alzheimers-disease).

How much benefit did lecanemab show in its pivotal trial?

The phase 3 Clarity AD trial enrolled 1,795 people with early Alzheimer's disease. On the Clinical Dementia Rating–Sum of Boxes scale, where higher scores indicate greater impairment, average worsening was 1.21 points with lecanemab and 1.66 with placebo. The 0.45-point difference corresponds to approximately 27% less worsening relative to placebo. Both groups nevertheless declined. [Clarity AD results in the New England Journal of Medicine](https://www.nejm.org/doi/full/10.1056/NEJMoa2212948).

That distinction matters when families hear percentage-based treatment claims. A relative reduction in decline does not mean memory improved by the same percentage, and an average trial result cannot predict one person's experience. The findings support a slowing effect over the trial period; they do not guarantee preserved independence for a particular number of years. A useful treatment discussion therefore connects the measured benefit with the person's priorities, such as managing familiar activities, while acknowledging uncertainty about the individual outcome. [Clarity AD study](https://www.nejm.org/doi/full/10.1056/NEJMoa2212948).

What safety checks and caregiving plans are needed?

A central concern is amyloid-related imaging abnormalities, or ARIA: brain swelling or bleeding that may appear on scans without noticeable symptoms. Serious and occasionally fatal events can occur. People carrying two copies of the APOE ε4 gene variant face higher ARIA risk; the FDA's donanemab guidance recommends testing before treatment to inform the discussion. Genetic results help assess risk but cannot determine with certainty whether a complication will occur. [FDA donanemab safety information](https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-treatment-adults-alzheimers-disease).

Monitoring requirements have evolved as safety reports accumulated. In August 2025, the FDA required an additional MRI before the third lecanemab infusion, supplementing baseline imaging and scans before the fifth, seventh and fourteenth infusions. The change illustrates why families need the current monitoring plan for the exact medicine being prescribed. New headache, confusion, vision changes or difficulty walking warrant immediate medical contact; seizures or sudden stroke-like symptoms require emergency evaluation. [FDA lecanemab safety communication](https://www.fda.gov/drugs/drug-safety-communications/fda-recommend-additional-earlier-mri-monitoring-patients-alzheimers-disease-taking-leqembi-lecanemab).

A practical implication is that the treatment decision includes more than accepting a prescription. Families should establish who will coordinate appointments, recognize changes and contact the clinical team. They can also ask what findings would lead to a treatment pause and how benefit will be reassessed. Support with routines, communication and caregiver wellbeing remains necessary, whether an amyloid-targeting medicine is appropriate or not. [Harvard Health's caregiving overview](https://www.health.harvard.edu/promotions/harvard-health-publications/alzheimers-disease-a-guide-to-coping-treatment-and-caregiving).