Researchers in the United States discovered that a medical-grade formulation containing purified tetrahydrocannabinol (THC) and cannabidiol (CBD) significantly reduced agitation in people with advanced dementia compared with a placebo. The findings, presented on July 14 at the Alzheimer’s Association International Conference in London, are the first from a clinical trial of this kind.
The study, known as the LiBBY trial (Life’s end Benefits of cannaBidiol and tetrahYdrocannabinol), enrolled 120 hospice-eligible adults with Alzheimer’s disease or other forms of dementia who were experiencing agitation. Conducted across 10 medical centres, researchers visited participants in their homes or care facilities throughout the trial.
The results were encouraging. After 12 weeks, nearly 90% of participants who received the THC/CBD treatment showed an overall improvement in their symptoms.
Agitation is one of the most difficult symptoms associated with advanced dementia, often causing restlessness, aggression, anxiety and emotional distress. It can be deeply distressing for patients and place an enormous emotional burden on family members and caregivers.
“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,” said Brigid Reynolds, MSN, APRN, ANP-BC, co-lead investigator from Georgetown University. “Current treatment options are limited and often carry significant side effects, underscoring the need for safer, more effective therapies.”
Existing medications such as morphine, Valium and Haldol have shown limited effectiveness in treating dementia-related agitation and can also produce unwanted side effects, making the search for better therapies increasingly important.
Participants in the study, whose average age was 80, were randomly assigned to receive either the THC/CBD formulation or a placebo. Neither the participants, their caregivers nor the clinicians knew who was receiving the active treatment, ensuring the results remained unbiased.
The medication consisted of purified THC and CBD delivered as a fast-acting oral oil suspension designed specifically for the trial.
Researchers measured agitation using the Cohen-Mansfield Agitation Inventory, a widely used assessment that evaluates 29 different agitation-related behaviours. Caregivers, who also administered the medication, rated each behaviour on a seven-point scale ranging from “never” to “several times per hour.”
Within just two weeks, participants receiving the THC/CBD treatment experienced an average 6.27-point greater reduction in agitation scores than those given a placebo. Those improvements continued through the full 12-week study, showing that the benefits were sustained over time.
A second behavioural assessment, known as the Clinical Global Impression of Change, produced similar results. At the two-week mark, nearly 84% of people receiving the treatment were rated as less agitated, compared with just over 30% of those receiving the placebo. After 12 weeks, that figure had risen to more than 87%, while improvement in the placebo group remained below 24%.
The treatment also appeared to be well tolerated. Rates of side effects, including infections and gastrointestinal disorders, were similar in both groups and reflected health issues commonly seen in this patient population.
For some families, the study offered more than scientific promise.
Laura, whose mother took part in the LiBBY trial, said she noticed meaningful changes during the study, even though she never learned whether her mother had received the active medication or the placebo.
“She seemed happier,” Laura said. “We experienced joy. There were still moments of connection.”
While the findings are promising, researchers stress that the treatment used in the trial is not comparable to cannabis products sold online or in dispensaries.
“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.”
The researchers thanked the participants, caregivers and families whose involvement made the study possible. The trial was funded by the U.S. National Institutes of Health and the Alzheimer’s Association and was conducted through the NIH-funded Alzheimer’s Clinical Trial Consortium, with coordination from the University of Southern California’s Epstein Family Alzheimer’s Therapeutic Research Institute, the Medical University of South Carolina and Georgetown University.
Although further research is needed, the LiBBY trial offers hope that a carefully developed THC/CBD medication could one day provide a safer and more effective way to ease one of dementia’s most challenging symptoms, helping patients experience greater comfort while giving families more moments of meaningful connection.
