A medically formulated THC and CBD treatment reduced agitation in a blinded trial involving people with late-stage dementia.
Restlessness, aggression, and emotional distress can make late-stage dementia especially difficult for patients and caregivers. In a first-of-its-kind U.S. clinical trial, a specially prepared medication containing tetrahydrocannabinol (THC) and cannabidiol (CBD), two active compounds in marijuana, significantly reduced agitation compared with a placebo.
Jacobo Mintzer, MD, of the Medical University of South Carolina, and Georgetown University’s Brigid Reynolds, MSN, APRN, ANP-BC, presented the main findings on July 14, 2026, at the Alzheimer’s Association International Conference in London.
Known as the LiBBY trial (Life’s end Benefits of cannaBidiol and tetrahYdrocannabinol), the study included 120 hospice-eligible participants with Alzheimer’s disease or another form of dementia who were experiencing agitation. Ten medical centers across the United States conducted study visits in participants’ homes or other places of residence. After 12 weeks, nearly 90% of those who received the treatment showed overall improvement.
“These trial results were extremely impressive and showed a level of response not seen before in clinical trials related to dementia. Rarely do we see close to 90% of patients in a trial respond positively to a new medication,” said Mintzer, the co-lead investigator.
“Agitation affects many people with late-stage dementia, causing symptoms such as restlessness, aggression, and emotional distress that can profoundly impact patients and their caregivers,” explained Reynolds, the co-lead investigator. “Current treatment options are limited and often carry significant side effects, underscoring the need for safer, more effective therapies.”
Current drugs offer limited relief
Morphine, Valium, and Haldol are among the medications used to manage dementia-related agitation, but they have shown limited effectiveness and can produce unwanted side effects.
The LiBBY trial examined the effectiveness, safety, and tolerability of purified THC and CBD delivered orally in a rapidly absorbed oil suspension. Participants, whose average age was 80, were randomly assigned to receive either the cannabinoid formulation or a placebo.
To limit bias, participants, caregivers, and clinicians were all kept unaware of which treatment each person received. Because the medication was designed to act quickly, the primary comparison took place after 2 weeks, followed by another assessment at 12 weeks.
Agitation was measured with the Cohen-Mansfield Agitation Inventory, a survey covering 29 behaviors associated with agitation. This allowed the investigators to compare changes among participants receiving THC and CBD with those receiving the placebo.
Agitation declines within two weeks
Caregivers, who also administered the medication, rated each behavior on a 7-point scale ranging from “never” to “several times per hour.” By the 2-week assessment, average agitation scores had fallen 6.27 points more in the THC and CBD group than in the placebo group. The reduction remained statistically significant at 12 weeks.
A second measure, the Clinical Global Impression of Change in Behavior assessment, produced a similar pattern. Improvement in agitation was reported for 83.9% of the THC and CBD group at 2 weeks, compared with 30.5% of the placebo group. At 12 weeks, the figures were 87.2% and 23.6%, respectively.
Rates of adverse events, including infections and gastrointestinal disorders, were similar between the treatment and placebo groups (46.7% vs 42.4%). Such events were considered expected within this patient population.
Laura, whose mother joined the LiBBY trial, said participating gave her hope that future treatments might improve life for families affected by dementia. She did not know whether her mother had received the cannabinoid medication or the placebo, but she noticed changes during their time together. “She seemed happier,” Laura said. “We experienced joy. There were still moments of connection.”
Commercial products are not equivalent
Despite the encouraging results, the medication tested in the trial was substantially different from THC and CBD products available commercially.
“People should not assume that products available at dispensaries or online are equivalent to what was studied in this trial,” Reynolds said. “The medication used in this research was carefully formulated, manufactured, and administered under close medical supervision. Over-the-counter or commercially available THC and CBD products may vary widely in their composition, quality, and dosing, making them potentially ineffective or even harmful.”
Meeting: Alzheimer’s Association International Conference
This trial was supported by an National Institutes of Health cooperative agreement grant #R01AG068324-01 and by the Alzheimer’s Association. It is being conducted by the NIH-funded Alzheimer’s Clinical Trial Consortium and coordinated by the University of Southern California’s Epstein Family Alzheimer’s Therapeutic Research Institute, the Medical University of South Carolina, and Georgetown University. The ClinicalTrials.gov ID is NCT05644262.
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