A new systematic review and meta-analysis published in The American Journal of Geriatric Psychiatry found that cannabinoid-based therapies were associated with reduced agitation and neuropsychiatric symptoms in patients with Alzheimer’s disease.

Researchers from the University of California and the University of Texas at San Antonio, along with researchers from Brazil’s Federal University of Ceará, Federal University of Minas Gerais, University Center of Belo Horizonte, Federal University of Piauí and Federal University of Pernambuco, reviewed randomized placebo-controlled trials evaluating cannabinoid-based therapies for agitation or related neuropsychiatric symptoms in Alzheimer’s disease.

The review included seven studies, six of which were randomized trials, with a total of 221 participants. Researchers found that cannabinoid-based therapies were linked to lower scores for overall neuropsychiatric symptoms and agitation compared to placebo.

In randomized between-group analyses, cannabinoid-based treatments were associated with lower Neuropsychiatric Inventory total scores, lower Cohen-Mansfield Agitation Inventory-Short Form scores and lower NPI agitation/aggression scores. Bayesian analyses also found a greater than 95% probability that cannabinoid-based therapies lowered symptom scores.

Somnolence, or drowsiness, was the primary safety concern, with participants receiving cannabinoid-based therapies more than twice as likely to experience it compared to those receiving placebo. Estimates for falls and fatigue were less precise.

“Cannabinoid-based therapies showed lower agitation and neuropsychiatric symptom scores than placebo in AD, with somnolence as the main safety concern,” the study concludes.

The authors emphasized that larger randomized trials are still needed, particularly those using specific formulations, longer follow-up periods, active comparators and more systematic safety monitoring.