LONDON — Primary findings from the LiBBY trial, a phase II study testing a purified combination of tetrahydrocannabinol (THC) and cannabidiol (CBD) for treating agitation in hospice-eligible dementia patients, were presented on July 14, 2026, at the Alzheimer's Association International Conference in London. The trial demonstrated statistically and clinically meaningful reductions in agitation among participants receiving the investigational formulation compared with placebo, offering potential new therapeutic pathways for a condition with few effective treatment options.

The LiBBY trial enrolled 120 hospice-eligible participants diagnosed with Alzheimer’s disease or other dementias who exhibited clinically agitation. Participants were randomized to receive either a THC-CBD formulation or a placebo in a double-blind design, meaning neither participants, caregivers, nor clinicians knew who received the active treatment. The THC-CBD formulation consisted of 4 mg THC and 200 mg CBD administered orally twice daily in a rapid-acting digestible oil suspension. The double-blind treatment phase lasted 12 weeks, with study visits conducted in participants’ homes or places of residence by staff from ten medical centers nationwide.

At the primary endpoint of 2 weeks, the mean between-group difference in Cohen-Mansfield Agitation Inventory (CMAI) scores was -6.27 points (95% CI -9.66 to -2.87, P<0.0004) in favor of the THC-CBD group. The CMAI measures 29 agitation behaviors on a 7-point scale, yielding total scores ranging from 29 to 203. By 12 weeks, the mean area under the curve contrast in CMAI scores between groups was -8.23 points (95% CI -11.6 to -4.86, P<0.0001), indicating sustained improvement over time. Clinical Global Impression of Change in Behavior scores showed that 83.9% of treated participants improved at 2 weeks compared with 30.5% on placebo, rising to 87.2% versus 23.6% at 12 weeks.

Jacobo Mintzer, MD, co-lead investigator of the trial from the Medical University of South Carolina and Georgetown University, noted the magnitude of response. “Rarely do we see close to 90% of patients in a trial respond positively to a new medication,” he said. Mintzer emphasized that agitation in this population is a serious clinical concern, stating, “Agitation is not trivial in this population.” The trial’s design also yielded methodological insights.

“The first is that a study in this population can be done and should be done,” Mintzer said. “The second is that if you're going to do a study on psychosis or agitation in this population, you need to go to the patient, not expect the patient to come to you.”

Elizabeth Edgerly, PhD, of the Alzheimer’s Association, the broader implications of the research. “The LiBBY study directly addresses one of the most challenging and under-discussed aspects of Alzheimer's disease -- end-of-life agitation,” she said. Edgerly added that the results “underscore the importance of prioritizing attention, care, and research for individuals in mid- and late-stage Alzheimer's and related dementias.” The Alzheimer’s Association supported the trial, which was conducted by the NIH-funded Alzheimer’s Clinical Trials Consortium and coordinated by the University of Southern California’s Epstein Family Alzheimer’s Disease Research Institute. It was also supported by National Institutes of Health cooperative agreement grant #R01AG068324-01.

The trial population reflected real-world demographics: the mean participant age was 80 years, 55% were women, more than half identified as members of an underrepresented ethnic or racial group, and 75% lived at home. This aligns with data showing that about half of Alzheimer’s disease patients use hospice care in their final days. Current pharmacological options for dementia-related agitation—including morphine, Valium, and Haldol—have demonstrated limited effectiveness and often carry burdensome side effects, underscoring the unmet need this trial sought to address.

Adverse event rates were 46.7% in the THC-CBD group and 42.4% in the placebo group, indicating a comparable safety profile during the double-blind phase. However, there were more deaths in the THC-CBD arm than in the placebo arm, though investigators reported no discernible pattern in the cause of death in either group. Participants who completed the 12-week double-blind phase could enroll in an extension study. Those who continued on THC-CBD maintained their benefits through week 24, while those who switched from placebo to active treatment at week 12 showed a decrease in agitation that persisted through the end of the extension period.

The formulation used in the trial is not publicly available and is not approved for any other indication. Mintzer stressed the importance of using standardized, purified cannabinoids: “Unless we work with purified CBD and THC, we will not know what we're doing.” He explained the pharmacological mechanisms, noting that “THC is a well-documented psychoactive that exerts a broad effect on the regulation of emotion and activates cannabinoid receptors directly,” while “CBD is a non-psychoactive marijuana component that activates hydroxytryptamine (5-HT1A) serotonin receptors, triggering an inhibitory response that slows 5-HT1A signaling with positive effects on anxiety, appetite, sleep, and pain.”

A caregiver identified only as Laura shared qualitative observations from her experience in the trial. “She seemed happier,” Laura said. “We experienced joy. There were still moments of connection.” These testimonials reflect the human impact behind the clinical metrics.

The LiBBY trial is one of the first randomized controlled trials specifically conducted in a hospice-eligible population with Alzheimer’s or other dementias, breaking new ground in late-stage disease research.

Agitation in late-stage dementia is a major source of distress for patients and caregivers, often leading to premature institutionalization and reduced quality of life. With existing medications offering limited relief and risks, the LiBBY trial provides rigorous clinical evidence that a precisely formulated THC-CBD combination may offer a safer, more effective alternative. The study’s home-based design also sets a precedent for conducting ethical, feasible research in vulnerable, homebound populations who are typically excluded from clinical trials.

The findings come at a time of growing interest in cannabinoid therapeutics, but the investigators caution against extrapolating results to commercial products. The trial’s strict protocol—using a defined dose of purified compounds under medical supervision—differs markedly from unregulated over-the-counter CBD or THC products, which vary widely in composition and quality. Future research will be needed to confirm these results in larger phase III trials and to assess long-term safety, particularly regarding mortality signals observed in this preliminary study.