THC-CBD Combination Reduces Agitation in End-Stage Dementia Within Two Weeks, but Serious Adverse Event Disparity Remains to Be Clarified

In advanced dementia, agitation is often more than a “behavioral problem”; it may also be the only remaining way for patients to express pain, fear, or other needs they cannot articulate. Now, a Phase 2 trial involving people with end-stage dementia has shown that a combination of tetrahydrocannabinol (THC) and cannabidiol (CBD) can reduce agitation within two weeks, offering a new option worthy of rigorous validation for a patient population that has long been difficult to include in clinical research.

LiBBY is a 12-week, randomized, double-blind, placebo-controlled, multicenter trial that enrolled 120 participants with Alzheimer’s disease or other dementias who were eligible for or already receiving hospice care and had clinically significant agitation. The study was conducted at 10 U.S. medical centers, with most visits completed in patients’ homes or residential settings. Participants were about 80 years old on average, and three-quarters lived in community settings.

The study used an oral oil formulation called T2:C100. During the first week, the treatment group received 2 mg of THC and 100 mg of CBD twice daily; the dose was then increased to 4 mg of THC and 200 mg of CBD per administration, twice daily. As measured by the Cohen–Mansfield Agitation Inventory, scores in the treatment group decreased by 6.27 points more than in the placebo group at week 2. By week 12, the between-group difference had widened to 8.23 points, meeting the primary and key secondary endpoints.

Clinicians’ assessments of overall change also showed a consistent pattern: at week 2, 83.9% of the treatment group were judged to have improved, compared with 30.5% of the placebo group; at week 12, the respective figures were 87.2% and 23.6%. These numbers suggest that the effect not only emerged quickly but may also persist for some time. However, the data released so far are insufficient to determine which manifestations of agitation improved the most or how the degree of improvement translated into practical differences in patient comfort, caregiver burden, or level of sedation.

Safety, however, leaves an important question that cannot be overlooked. Overall adverse event rates were similar between the groups, at 46.7% in the treatment group and 42.4% in the placebo group; however, serious adverse events occurred in 23.3% and 11.9% of participants, respectively. The researchers determined that none of these events was related to the study drug, but in a study of only 120 people, the nearly twofold numerical disparity in the treatment group still requires clarification through complete event data, information on treatment discontinuations, and further research. Concerns cannot be dismissed solely on the basis of the causality assessment.

This trial focused on a specific population with late-stage disease who were eligible for hospice care. The results cannot be directly generalized to people with earlier-stage dementia, nor do they indicate that ordinary THC- or CBD-containing products have the same effect. Nonpharmacological measures remain the first-line approach for managing behavioral and psychological symptoms associated with dementia. Until the full peer-reviewed paper, data from the open-label extension period, and larger-scale validation are made public, these findings are best viewed as a strong but still preliminary clinical signal.