A week ago, researchers at the University of Florida published a study in Nature Metabolism suggesting that glucosamine — the joint supplement taken by tens of millions of older Americans — may accelerate the progression of Alzheimer's disease by 25 percent. The finding prompted alarm, and appropriately so. But it also provides an important moment to step back and survey a landscape that has changed profoundly since 2023: Alzheimer's disease is no longer untreatable, and for the first time in history, Americans can be tested for the biological changes of Alzheimer's before symptoms appear and treated with disease-modifying therapies before irreversible damage accumulates.
This is the story of where Alzheimer's medicine stands in June 2026 — grounded in the most current approved therapies, the FDA-cleared blood test now available in clinics, and the lifestyle interventions backed by the strongest evidence.
Two FDA-Approved Disease-Modifying Treatments
The most significant shift in Alzheimer's medicine is the arrival, for the first time, of FDA-approved drugs that have been shown to actually slow disease progression rather than merely managing symptoms.
Lecanemab (Leqembi), developed by Eisai and Biogen, received full FDA approval in July 2023 and has since been working through the insurance access landscape, with Medicare coverage now available for patients who meet clinical criteria. Lecanemab is a monoclonal antibody that targets and removes amyloid plaques from the brain — the protein aggregates that are one of the two hallmark pathological features of Alzheimer's disease. In the Phase 3 CLARITY AD trial, lecanemab slowed the rate of cognitive decline by approximately 27 percent over 18 months compared to placebo. For patients in the early stages of the disease — mild cognitive impairment or mild dementia with confirmed amyloid pathology — lecanemab offers the first option for meaningfully altering the course of the disease rather than simply managing symptoms.
Donanemab (Kisunla), developed by Eli Lilly, received FDA approval in July 2024 based on Phase 3 TRAILBLAZER-ALZ 2 trial results showing a 35 percent slowing of clinical decline in patients with early symptomatic disease. Kisunla is also an amyloid-targeting antibody and is notable for a "treat-to-clear" design: patients stop receiving infusions when amyloid is fully cleared from their brain, rather than continuing indefinitely. This approach reduces overall treatment burden and has been associated with favorable treatment completion rates.
Both drugs are administered as intravenous infusions in monitored clinical settings, given every two or four weeks. Both carry a risk of amyloid-related imaging abnormalities (ARIA) — small bleeds or fluid accumulations in the brain, most of which are asymptomatic but require MRI monitoring. Neither drug is appropriate for patients with moderate to severe Alzheimer's, as the phase where brain damage is already substantial. Both require confirmed amyloid pathology before treatment — meaning patients must have either a positive amyloid PET scan or a positive blood or CSF biomarker result.
The Blood Test That Changes Who Can Be Diagnosed Early
The FDA cleared the Lumipulse G pTau217 ratio blood test for use in adults aged 55 and older who are exhibiting symptoms of cognitive decline, making it the first blood-based Alzheimer's diagnostic approved in the United States. The test measures the ratio of phosphorylated tau 217 to beta-amyloid in blood plasma, with 91.7 percent of positive results confirmed by amyloid PET scan or CSF testing. It can replace — in many cases — the need for an amyloid PET scan that would otherwise cost $3,000 or more and involve radiation exposure.
A Harvard-affiliated Mass General Brigham study published April 14, 2026 in Nature Communications showed that pTau217 blood levels can detect early Alzheimer's disease progression even before amyloid PET scans show abnormalities — meaning the window for early detection has moved earlier than previously thought possible.
What the Prevention Evidence Actually Shows
For people without symptoms — the seven to eight million Americans likely in the preclinical stage of Alzheimer's — the lifestyle interventions with the strongest evidence base include aerobic exercise (150 minutes per week of moderate intensity), management of cardiovascular risk factors (blood pressure, cholesterol, blood sugar), hearing loss treatment, and adequate sleep. The Lancet Commission on Dementia Prevention, Intervention, and Care has identified 12 modifiable risk factors that together account for approximately 40 percent of Alzheimer's and dementia cases — each one of which represents a prevention opportunity.
The addition of glucosamine to the list of potential risk-modifying factors — in the direction of increased risk — is now a conversation item for patients with memory concerns, even if causality is not established. Anyone over 55 with memory concerns or a family history of Alzheimer's should discuss pTau217 blood testing with their physician.
Frequently Asked Questions
Q: Are there now drugs that can slow Alzheimer's disease?
A: Yes. Lecanemab (Leqembi, FDA-approved July 2023) slowed cognitive decline by 27% in Phase 3 trials. Donanemab (Kisunla, FDA-approved July 2024) slowed decline by 35%. Both are for early symptomatic disease with confirmed amyloid pathology.
Q: Who qualifies for these new Alzheimer's drugs?
A: Adults with mild cognitive impairment or mild Alzheimer's dementia who have confirmed amyloid pathology (positive PET scan or blood/CSF biomarker), no significant brain bleeding history, and meet clinical eligibility criteria. Neither drug is approved for moderate or severe Alzheimer's.
Q: What is the Lumipulse pTau217 blood test and where can I get it?
A: An FDA-cleared blood test for adults 55 and older with symptoms of cognitive decline. It measures pTau217-to-beta-amyloid ratio to detect amyloid pathology. Available at clinics offering Alzheimer's diagnostic services; discuss with your primary care provider or neurologist.
Q: What lifestyle factors most strongly protect against Alzheimer's?
A: Aerobic exercise, blood pressure control, cholesterol management, blood sugar control, hearing loss treatment, avoiding smoking, limiting alcohol, and adequate sleep. The Lancet Commission identifies these as part of 12 modifiable risk factors accounting for 40% of Alzheimer's cases.
Q: Should people stop taking glucosamine because of the new study?
A: The study showed an association — not proven causation — between glucosamine and faster Alzheimer's progression in people with mild cognitive impairment. Anyone with memory concerns should discuss their supplement use, including glucosamine, with their physician.
