A combination of purified THC and CBD has produced striking reductions in agitation among people with late-stage dementia, according to results from a US clinical trial presented at the Alzheimer's Association International Conference in London.

The findings, reported by The Independent and the conference organisers on 14 July 2026, come from the LiBBY trial — the Life's End Benefits of cannaBidiol and tetrahYdrocannabinol study — and offer early hope for one of dementia's most distressing symptoms.

What the trial tested

LiBBY was a multicentre, randomised, double-blind, placebo-controlled Phase 2 study involving 120 people with Alzheimer's disease or other dementias who were hospice-eligible and experiencing significant agitation.

Participants received either a novel oral oil containing 2mg of delta-9-THC and 100mg of CBD twice daily, or a placebo. Visits were conducted at home across ten US medical centres, with caregivers administering the doses and rating behaviour.

Agitation was measured using the Cohen-Mansfield Agitation Inventory — a standard scale covering behaviours such as restlessness, aggression and verbal outbursts, rated from "never" to "several times per hour".

The headline results

Researchers said the trial met its primary and key secondary endpoints. After two weeks, the active treatment group showed a 6.27-point greater reduction in agitation scores than placebo — a difference described as clinically meaningful.

By 12 weeks, nearly nine in ten participants on the THC/CBD formulation showed overall improvement. Conference materials reported sustained benefit through the full study period.

"These trial results were extremely impressive and showed a level of response not seen before in clinical trials related to dementia," said lead investigator Jacobo Mintzer of the Medical University of South Carolina. "Rarely do we see close to 90 per cent of patients in a trial respond positively to a new medication."

Brigid Reynolds, a nurse practitioner at Georgetown University who helped present the data, said agitation in late-stage dementia causes "restlessness, aggression and emotional distress" that profoundly affects patients and families.

Why existing drugs fall short

Agitation and aggression are common in advanced dementia and are often harder to manage than memory loss itself. Conventional sedatives and antipsychotics — including drugs such as morphine, diazepam (Valium) and haloperidol (Haldol) — have shown limited benefit for many patients and can carry serious side effects in frail older adults.

That unmet need is why a well-controlled cannabis-based formulation has drawn attention, even before full peer-reviewed publication.

Families noticed a difference

One caregiver, identified only as Laura, said her mother took part in the trial. Although the study was blinded, Laura described moments of renewed connection during visits.

"We experienced joy. There were still moments of connection," she said, according to reporting of the conference presentation.

Anecdotes like this illustrate why agitation research matters, but they are not a substitute for the trial's formal outcome measures.

Not your local CBD oil

Researchers were explicit that the LiBBY product is not interchangeable with high-street cannabis oils, vape liquids or unregulated CBD brands.

"The medication used in this research was carefully formulated, manufactured, and administered under close medical supervision," Reynolds said. "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 trial drug — known in study documents as T2:C100 — is a pharmaceutical-grade oral suspension with defined THC and CBD ratios, not a consumer wellness product.

What it means for UK readers

This was a US study in hospice-eligible patients. It has not yet been peer reviewed or published in a medical journal, and no regulator has approved the formulation for dementia agitation.

Medical cannabis is legal in Britain on prescription, but NHS access remains limited and indications are narrow. A successful Phase 2 result does not automatically translate into UK clinical practice — a larger Phase 3 trial would be needed first.

Even so, the LiBBY data land at a moment of intense interest in cannabinoids for neuropsychiatric symptoms. For families watching a loved one distressed by late-stage dementia, the prospect of a targeted THC/CBD therapy — administered medically, not bought online — is likely to attract close attention on both sides of the Atlantic.

What happens next

Investigators said planning for a Phase 3 study is under way, potentially extending beyond hospice care to moderate and severe dementia with agitation.

Until then, clinicians and carers should treat these results as promising conference-topline data, not a treatment they can replicate at home.

Reporting based on coverage in The Independent and the Alzheimer's Association AAIC 2026 release, 14 July 2026. The LiBBY trial (NCT05644262) has not yet completed peer review.