Can weed help dementia patients? Study finds surprising upsides

High hopes for those with dementia.

New research has found an unexpected benefit for a common symptom in those with late-stage Alzheimer’s and other dementias from a cannabis treatment after a matter of weeks.

The results mark a major step in dementia treatment, especially as more than 7 million Americans currently have Alzheimer’s, a number that’s expected to nearly double by 2060.

The findings, reported for the first time at the 2026 Alzheimer’s Association International Conference, were from the Phase 2 LiBBY (Life’s End Benefits of cannaBidiol and tetrahYdrocannabinol) clinical trial.

120 adults with dementia who were experiencing clinically significant agitation — a common sign of cognitive decline — took a new oral formulation that combined 2 milligrams of THC and 100 milligrams of CBD twice a day.

Within two weeks, nearly 84% of those receiving the treatment saw improvements in agitation, which then increased to nearly 9 in 10 patients showing overall improvements after 12 weeks of treatment.

Only 30% of patients on the placebo showed fewer signs of agitation after two weeks, which dropped to 23% at the end of 12 weeks.

The study also shows that those with late-stage dementia can be included in clinical trials, helping expand research.

“We now have evidence supporting a new and very effective treatment approach for agitation that may be appropriate for people in the final stages of dementia at the end of life,” lead investigator Jacobo Mintzer said in a press release.

“These results not only highlight a promising therapeutic option, but also underscore the importance of prioritizing attention, care and research for individuals in mid- and late-stage Alzheimer’s and related dementias,”  Elizabeth Edgerly, Alzheimer’s Association vice president, said in a press release.

While more than half of those living with dementia are affected by agitation, common prescription medications such as benzodiazepines, opioids and antipsychotics aren’t always effective and have significant risks.

Agitation can be characterized by emotional distress, excessive motor activity and verbal or physical tension, and often serves as a signal of physical discomfort, fear or unmet needs in those who have lost the ability to communicate.

Research is mixed on whether marijuana can be harmful or helpful for aging brains.

There can be downsides, as previous studies have found THC can harm learning and memory, although the exact reason why isn’t clear.

Meanwhile, other studies have found that middle-aged and older adults who use the drug may actually see some brain and cognitive benefits.

One such study of mice found that low doses of THC may protect memory and reduce brain damage linked to Alzheimer’s when combined with COX-2 inhibitors, an anti-inflammatory medication.

Other research into THC has found that it can have medical benefits, including anti-inflammatory and neuroprotective properties.