THC-CBD Oil Eased Agitation in Late-Stage Dementia Trial

A purified formulation of THC and CBD sharply reduced agitation in people with advanced dementia who were eligible for hospice care, according to results from one of the first randomized controlled trials to test the combination in this population. The findings¹ were presented at the Alzheimer’s Association International Conference in London on July 14, 2026, and come from a mid-stage study that met both its primary and key secondary goals.

The study, known as the LiBBY trial, enrolled 120 patients with Alzheimer’s disease or another form of dementia who had clinically significant agitation. Agitation affects roughly half of people with dementia near the end of life, and about a third continue to have symptoms despite treatment. No medication is approved specifically to treat it, which leaves clinicians reaching for antipsychotics, benzodiazepines and opioids — drugs that work unreliably and carry real risks in frail, elderly patients.

What the trial measured

LiBBY was a multicenter, randomized, double-blind, placebo-controlled Phase 2 study, the design that carries the most weight in clinical research, because neither patients, their caregivers, nor the treating clinicians knew who received the active drug. Participants averaged about 80 years of age, 55% were women, and most lived at home rather than in a care facility. More than half came from ethnoracial groups usually underrepresented in research — a group investigators have long struggled to enroll and keep in dementia studies.

Patients received an oral oil, starting at a half dose of 2 mg THC and 100 mg CBD twice daily for the first week, then moving to 4 mg THC and 200 mg CBD twice daily through week 12. The main measure was the Cohen-Mansfield Agitation Inventory, a 29-behavior scale scored by caregivers, assessed at two weeks — an early checkpoint chosen because the formulation is fast-acting.

At two weeks, the treatment group’s agitation scores fell 6.27 points further than the placebo group’s, a statistically significant gap that widened to an 8.23-point advantage by week 12. On a separate, clinician-rated measure of overall change, about 87% of treated patients had improved by week 12, compared with 24% on placebo. The result adds to a run of controlled trials putting medical cannabis on firmer scientific footing, even as most of them target very different conditions.

“Rarely do we see close to 90% of patients in a trial respond positively to a new medication,” said co-lead investigator Jacobo Mintzer of the Medical University of South Carolina. Response rates that high are unusual in dementia research, where most candidate drugs fail outright.

A reassuring safety picture, with one caveat

Overall side-effect rates were similar between the two groups, 46.7% versus 42.4%, and the researchers did not see the problems clinicians tend to fear when giving THC to older adults, such as excessive sedation, hallucinations or heightened anxiety. Restlessness, which some standard sedatives make worse, improved.

One number complicates the clean topline. Serious adverse events occurred in 23.3% of the treatment group over 12 weeks, roughly double the 11.9% rate on placebo, though investigators judged that none were related to the study drug. Serious events are expected in a hospice-eligible population, but the gap is the kind of signal a confirmatory trial will need to examine closely. A separate open-label extension, in which everyone received the active drug from weeks 13 to 24, suggested the benefit held and that the drug stayed safe across the full period.

Why the formulation matters

The trial was funded by the National Institute on Aging and the Alzheimer’s Association and run through the NIH-backed Alzheimer’s Clinical Trial Consortium. The cannabinoid oil itself was developed and supplied by MediPharm Labs (LABS.TO ), a Canadian pharmaceutical manufacturer that retains the rights to the formulation and is now reviewing the data and weighing regulatory next steps, including possible patent filings.

That commercial backdrop points to the study’s central practical message: the product tested here is a purified, precisely dosed pharmaceutical, not something a family can replicate at a dispensary counter. The distinction between medical-grade cannabinoid formulations and retail products is one researchers keep having to redraw. The investigators were emphatic on the point. “People should not assume that products available at dispensaries or online are equivalent to what was studied in this trial,” said co-lead investigator Brigid Reynolds of Georgetown University, who noted that over-the-counter cannabinoid products vary widely in composition and dose.

For now, the results are topline data from a conference presentation, not a peer-reviewed publication, and a single Phase 2 trial rarely settles a clinical question on its own. Other cannabinoid findings that looked promising in early studies remain unproven in the clinic for exactly that reason.

A larger confirmatory study would be needed before any cannabinoid therapy could win approval for dementia agitation, a regulatory route other cannabinoid candidates are only starting to travel. What the LiBBY trial establishes is narrower but still meaningful: that a carefully controlled study can be run in dying patients whom most research has ignored, and that it can produce a clear answer.

References:

^{1. Mintzer, Jacobo; Reynolds, Brigid; et al. “The Life’s End Benefits of cannaBidiol and tetrahYdrocannabinol (LiBBY) Study” (2026). Alzheimer’s Association International Conference 2026, London. https://aaic.alz.org/downloads2026/LiBBYTrialresults.pdf}