What if slowing Lewy body dementia (LBD) meant addressing more than one change in the brain? And what if you, or someone you care for, could help find out?
That question is now being tested in a clinical trial that is open and enrolling. In June, we shared that TRAILBLAZER-ALZ 7 was getting underway. Study sites are now open and looking for volunteers.
Why this study looks at two proteins
LBD is associated with a misfolded protein called alpha-synuclein, which gathers into clusters called Lewy bodies and is associated with the dysfunction and loss of brain cells. But alpha-synuclein is not always the only protein involved. Many people with LBD also have amyloid, a protein best known for forming plaques between brain cells in Alzheimer’s disease. In the context of LBD or Parkinson’s disease, having amyloid as well is called Alzheimer’s co-pathology.
Amyloid is present in an estimated 50 - 80% of people with dementia with Lewy bodies (DLB) and up to half of people with Parkinson’s disease. When it appears alongside alpha-synuclein, research has linked the combination to earlier onset of dementia symptoms, faster decline, and reduced life expectancy compared with either protein alone. Biomarkers now make it possible to detect both proteins in a living person. That is what makes a study like this one possible.
What the study is testing
The study is testing donanemab, an antibody treatment given through an IV that attaches to amyloid and helps the body clear it. Donanemab does not remove alpha-synuclein. It is approved by the U.S. FDA for early Alzheimer’s disease, but not for Lewy body disease. TRAILBLAZER-ALZ 7 is a Phase 2 study, an early test of whether the drug is safe and shows enough promise to justify larger trials. Researchers will look at whether clearing amyloid slows changes in thinking and in the ability to manage everyday activities in people who have both alpha-synuclein and amyloid.
Eli Lilly and Company is the study sponsor. About 350 participants between the ages of 55 and 85 will be randomly assigned to receive either donanemab or a placebo, and no one involved will know which. Participation lasts about a year and a half. It includes a screening period of up to 120 days, 48 weeks of treatment with an infusion about every four weeks, and up to 12 weeks of follow-up. Participants complete memory and thinking tests, brain imaging, and MRI scans along the way. A study partner who knows your day-to-day abilities and can come to visits is required. Usually, but not always, this is a spouse, adult child, or friend. There is no cost to take part, and reimbursement for travel and other study-related expenses may be available.
At the end of the trial, participants will be offered the opportunity to enroll in a long-term extension study funded by the U.S. NIH. In this extension study, participants who were on placebo during the main trial will be switched to active treatment with donanemab.
Who may be able to take part
A person may be eligible if they have had gradually worsening memory or thinking problems for at least six months and have mild cognitive impairment, meaning the changes are noticeable but they are still largely managing on their own. They also need at least one core feature of DLB: alertness and attention that come and go, recurring visual hallucinations, acting out dreams during sleep, or Parkinson’s-like movement changes such as slowness, stiffness, or tremor at rest. Finally, the study team will confirm that both alpha-synuclein and amyloid are present in the brain.
You do not need to know your biomarker results before contacting a study site. The study team will do its own testing during screening, including a spinal fluid test, to answer that question. People who take medications for memory, LBD, or Parkinson’s symptoms may still be able to join if their dose has been steady for at least 30 days.
A note for people with Parkinson’s disease
The study is open to people with Parkinson’s disease as well. Parkinson’s-like movement changes are themselves one of the core features of DLB, so a person with Parkinson’s disease already has at least one. They still need to meet the other requirements for this study, including mild cognitive impairment and the study team will still need to confirm biomarker evidence for both proteins. If that describes you or someone you care for, this study may be worth a close look.
Learn more and find a site
To learn more about Alzheimer’s co-pathology in LBD, watch the recording of “The Alzheimer’s Connection: Co-Pathology in Lewy Body Dementia”. In this webinar from LBDA’s 2026 Community Webinar Series, Dr. Shannon Chiu, lead principal investigator of the LBDA Arizona Collaborative Research Center of Excellence, discusses what is known about Alzheimer’s co-pathology, what it means for the course of the disease, and why it matters for research happening now, including TRAILBLAZER-ALZ 7.
For more details, visit the TRAILBLAZER-ALZ 7 study page. It lists currently recruiting sites in ten states, with the principal investigator and phone number for each. More locations are expected to open, and the study is also enrolling outside the United States. To learn more from a member of the study team, you can call the site nearest you or call the sponsor’s information line listed on the page.
It is worth being clear about what a study like this can tell us. As a Phase 2 trial, it is designed to learn about safety and whether there is a signal worth pursuing. Some participants will receive a placebo. But for a community that has long waited for treatments aimed at the disease itself rather than just treating symptoms, every person who takes part helps move the answer closer.
If this study is not the right fit for you or someone you know, consider joining LBDA’s Lewy Trial Tracker. By signing up, you will be notified of new research studies and clinical trials seeking participants from the LBD community.
