What are the proven treatments for Alzheimer’s disease and how effective are they?
Executive summary
Proven treatments for Alzheimer’s disease fall into two camps: modest symptomatic drugs that have been used for decades (cholinesterase inhibitors and memantine) and newer anti-amyloid immunotherapies that slow clinical decline in early-stage patients (lecanemab, donanemab) but do not cure the disease and carry notable risks and limits to effectiveness [1] [2] [3]. Non‑drug approaches and behavioural management remain central to care, and many promising avenues—tau therapies, vaccines, precision approaches—are still experimental [2] [4] [5].
1. Proven disease‑modifying therapies: who they help and how much they help
Two anti-amyloid monoclonal antibodies have regulatory approval and clinical evidence showing they reduce brain amyloid and slow decline in people with biomarker-confirmed early Alzheimer’s (mild cognitive impairment or mild dementia): lecanemab and donanemab (Kisunla) demonstrated statistically significant slowing of cognitive and functional decline in phase 3 trials and were approved for use in this early population [2] [3] [6]. Measured benefits are real but modest: trials reported slowed decline on composite scales in the range of roughly a quarter to a third versus placebo depending on the outcome used — not reversal of disease or large restoration of lost function [6] [7]. Importantly, both drugs were studied and approved only in patients with biomarker evidence of amyloid and in early stages, so there are no proven benefits for moderate or advanced Alzheimer’s outside those trial populations [8] [3].
2. Symptomatic medicines: modest cognitive and functional effects
Cholinesterase inhibitors (donepezil, rivastigmine, galantamine) and the NMDA antagonist memantine remain the backbone of symptomatic treatment and are proven to provide small improvements in cognition, activities of daily living, and behaviour for many patients, particularly in mild to moderate stages [1] [9]. Meta-analyses estimate average improvements on global cognitive tests of about 1 to 1.5 points on a 30‑point MMSE-type scale over 6–12 months, with only a subset of patients showing clinically meaningful benefit (roughly one-third) and overall effect sizes characterised as modest [10] [9]. Memantine can help some people in moderate to severe stages maintain certain daily functions for months longer than without treatment [2].
3. Risks, caveats and who might be harmed
Anti-amyloid antibodies carry specific safety concerns, including amyloid‑related imaging abnormalities (ARIA) such as cerebral swelling and microhemorrhages; risk increases with age, APOE ε4 status, and higher antibody doses, and was a major focus in trials and prescribing guidance [9] [8]. Cholinesterase inhibitors and memantine have well-described side‑effect profiles that limit tolerability in some patients, and evidence for many interventions remains low or mixed, meaning clinicians must weigh small average benefits against harms for each person [10] [1]. Regulatory approvals for new biologics are tied tightly to the specific trial populations and biomarker criteria used, exposing an implicit industry and clinical agenda to target early, biomarker‑positive disease rather than later stages [3] [8].
4. Non‑drug strategies and symptom management matter most for quality of life
Evidence supports behavioural and non‑drug interventions to manage agitation, depression and other psychiatric symptoms and to improve caregiver outcomes, and experts recommend trying these approaches before resorting to antipsychotics or other higher‑risk medicines [2] [11]. Lifestyle measures and symptomatic supports do not cure Alzheimer’s, and large randomized trials have generally failed to show that single supplements or alternative “medical foods” prevent or treat the disease, so non‑drug care focuses on function, safety and comfort rather than disease eradication [12] [11].
5. The horizon: multiple targets, qualified optimism and remaining uncertainty
Research is accelerating beyond amyloid—vaccines, tau-targeting agents, anti-inflammatory and metabolic strategies, precision medicine frameworks and combination approaches are in various stages of trials—but many prior candidates failed in late‑stage testing and the field recognizes amyloid reduction alone is unlikely to be sufficient for most patients [4] [5] [13] [14]. Early trial signals, biomarker advances and new antibodies (and newer candidates like remternetug) suggest incremental progress, but the practical effect sizes, long‑term safety, cost, and access questions remain unresolved and must temper enthusiasm [14] [7].