For the first time in the 120-year history of Alzheimer's disease research, American doctors can offer patients something that was once considered impossible: treatments that measurably slow the progression of the disease itself. As of 2026, two FDA-approved disease-modifying therapies are being administered to thousands of patients across the United States. The research pipeline contains more drug candidates than at any prior point in history. And the field is beginning to ask a question that would have seemed fantastical a decade ago: can Alzheimer's be prevented?
"The current Alzheimer's disease treatment landscape is the most exciting in the field's history," said Dr. Parichita Choudhury, MD, cognitive neurologist and associate director of the memory clinic at Banner Sun Health Research Institute, speaking at the 2026 American Academy of Neurology Annual Meeting.
Leqembi and Kisunla: What the First Disease-Modifying Drugs Are Actually Doing
Lecanemab, sold as Leqembi and approved by the FDA in 2023, and donanemab, sold as Kisunla and approved in 2024, work by binding to and facilitating the clearance of amyloid beta — the sticky protein that forms plaques in the brains of Alzheimer's patients and is widely believed to be a primary driver of neuronal damage. Both drugs are given as intravenous infusions: Leqembi every two weeks, Kisunla every four weeks.
In their pivotal clinical trials, Leqembi slowed cognitive decline by approximately 27 percent and Kisunla by approximately 35 percent compared to placebo in patients with early-stage Alzheimer's disease — defined as mild cognitive impairment or mild dementia with confirmed amyloid pathology. These are not cures, and the drugs do not reverse existing damage. They slow the rate of decline, which for patients and families managing a devastating disease means meaningfully more time at higher functional levels.
The drugs carry significant risks, principally amyloid-related imaging abnormalities (ARIA) — episodes of brain swelling or microbleeding that appear on MRI and can cause headache, confusion, or in rare cases more serious neurological events. The frequency and management of ARIA require careful monitoring protocols, regular MRI scans, and close collaboration between neurology, radiology, and pharmacy teams. These monitoring demands have required healthcare systems to develop new clinical infrastructure for administering the drugs safely.
According to BrightFocus Foundation, both Leqembi and Kisunla are now available in the United States and multiple other countries, with researchers continuing to refine dosing protocols. Leqembi received a maintenance dosing approval — IV infusions every four weeks instead of two after an initial treatment period — in January 2025, improving its practicality for patients.
The 2026 Pipeline: 192 Trials, 158 Candidates, Multiple New Approaches
The drug development pipeline for Alzheimer's disease in 2026 is the largest and most diverse in the history of the field. A comprehensive analysis published in Alzheimer's & Dementia: Translational Research & Clinical Interventions in May 2026 by Dr. Jeffrey Cummings and colleagues catalogued 192 clinical trials evaluating 158 drug candidates across Phase 1, 2, and 3 development.
Eight Phase 3 trials are scheduled to reach primary completion in 2026, including trials of AR1001 (a phosphodiesterase 5 inhibitor), metformin (the diabetes medication being tested for Alzheimer's), valiltramiprosate (an amyloid anti-aggregation agent), and xanomeline plus trospium (for Alzheimer's-related psychosis). The Phase 3 trial of donanemab in preclinical, pre-symptomatic Alzheimer's patients may also produce a readout in 2026 if the analysis threshold is met.
Beyond amyloid, the pipeline is increasingly diverse. Tau-targeting therapies — addressing the second major protein pathology in Alzheimer's, the neurofibrillary tangles made of tau protein — are advancing through Phase 2 and Phase 3 trials with promising early results. Neuroinflammation modulators targeting microglial dysfunction are in active development. GLP-1 receptor agonists, originally developed for diabetes and obesity, are being tested for Alzheimer's neuroprotection based on their observed ability to reduce brain inflammation and support neuronal survival.
The Prevention Frontier: Treating Before Symptoms Appear
Perhaps the most profound development in the Alzheimer's landscape of 2026 is the movement into prevention. For the first time, both lecanemab and donanemab are being evaluated in clinical trials designed to treat patients who have amyloid accumulation in their brains but have not yet developed cognitive symptoms. These individuals — identified through blood-based biomarker tests that have recently become clinically available — are in the pre-symptomatic phase of the disease, years before any memory impairment would be detected on a standard clinical evaluation.
"We can now detect changes in the brain before symptoms ever appear, and that gives us a therapeutic window," said Dr. Choudhury at the AAN. "Trials using both lecanemab and donanemab are attempting to remove amyloid in at-risk patients before symptom onset, and we should have readout data in a couple of years."
Blood-based biomarker tests for amyloid — including the widely available plasma phospho-tau 217 test — have made it possible to screen for early Alzheimer's pathology in a primary care setting without requiring expensive and specialized PET brain imaging. This has the potential to dramatically expand the number of patients who can be identified and offered treatment in the early stages, where current therapies are most effective.
Frequently Asked Questions
Q: What are Leqembi and Kisunla, and how do they work?
A: Leqembi (lecanemab) and Kisunla (donanemab) are FDA-approved antibody drugs that bind to and clear amyloid plaques from the brain, slowing Alzheimer's progression by 27-35% in early-stage patients.
Q: Who is eligible for Leqembi or Kisunla?
A: Adults with early Alzheimer's disease — mild cognitive impairment or mild dementia — with confirmed amyloid pathology verified by PET scan or cerebrospinal fluid testing. They are not indicated for moderate or advanced Alzheimer's.
Q: How many Alzheimer's drugs are currently in clinical trials?
A: As of May 2026, there are 158 drug candidates being evaluated in 192 clinical trials across Phases 1, 2, and 3, according to the annual pipeline analysis by Dr. Jeffrey Cummings published in Alzheimer's & Dementia.
Q: Can Alzheimer's be detected before symptoms appear?
A: Yes. Blood-based biomarker tests, particularly plasma phospho-tau 217 assays, can now detect Alzheimer's-related changes in the brain years before cognitive symptoms appear. Prevention trials are evaluating whether treating in this window can delay or prevent the disease.
Q: Are these drugs available on Medicare?
A: Yes. Medicare covers Leqembi and Kisunla for eligible patients with confirmed early Alzheimer's, though coverage requires participation in a data collection registry and specific qualifying criteria for some plans.
