The LiBBY trial's own safety data gives adult children a specific number to ask about: serious adverse events occurred in 23.3% of participants taking the THC/CBD combination versus 11.9% on placebo over 12 weeks. That is roughly double, even though overall side-effect rates were similar between the two groups and investigators judged the serious events unrelated to the study drug, according to the Alzheimer's Association's LiBBY results release.
LiBBY was a Phase 2 randomized, double-blind, placebo-controlled study of an oral THC/CBD combination — 2 mg THC plus 100 mg CBD per dose — for agitation in people with dementia who were hospice-eligible. "Agitation" here means the restlessness, pacing, shouting, and resistance to care that often make late dementia unmanageable at home. The trial met its primary endpoint, and that result is what will prompt families to ask about enrolling a parent in the next round of research.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- What LiBBY actually measured, and in whom
- How to read the doubled serious adverse event rate
- Research is not treatment, and the approved alternative has its own warning
- Who is legally allowed to enroll a parent
- The study partner role you would be taking on
- Frequently Asked Questions
What LiBBY actually measured, and in whom
The trial enrolled 120 people with Alzheimer's or another dementia who were both hospice-eligible and clinically agitated. Agitation was scored on the Cohen-Mansfield Agitation Inventory, a standard rating scale. At week 2, scores in the THC/CBD group fell 6.27 points more than placebo, and the Alzheimer's Association's AAIC 2026 release reported that as a met primary endpoint. The benefit held.
At week 12 the THC/CBD arm showed an 8.23-point greater reduction than placebo, and a separate completed 12-week open-label extension — where everyone knows they are receiving the drug — was also reported at the conference. The enrollment criteria are the part most families skip. Hospice eligibility means these were end-of-life patients. A parent with mild or moderate dementia is not the population LiBBY studied, and the effect size measured in hospice-eligible patients cannot be assumed to carry over.
How to read the doubled serious adverse event rate
A "serious adverse event" in trial reporting is a defined category: death, hospitalization, a life-threatening episode, or significant disability. It does not mean the drug caused it. In a hospice-eligible population, hospitalizations and deaths are expected at a meaningful rate regardless of what anyone is taking.
That is the context for 23.3% versus 11.9%. Investigators judged the serious events unrelated to the study drug, and the overall adverse event rate — all side effects, mild included — was similar between arms. But 120 participants split into two groups is a small sample, and a gap that size in a small trial is exactly the kind of signal a larger Phase 3 exists to resolve. Questions worth asking a study coordinator about any follow-on trial:.
- What were the serious adverse events, by type, not just by count?
- Who adjudicated whether they were drug-related, and was that person unblinded?
- What is the stopping rule if the imbalance appears again?
- Does the data safety monitoring board report to the funder or independently?
Research is not treatment, and the approved alternative has its own warning
No THC/CBD product is FDA-approved for dementia agitation. The LiBBY findings are topline Phase 2 results presented at a conference, with the open-label extension still being reported. Enrolling a parent means enrolling them in research — the goal is knowledge, and benefit to the individual participant is a possibility, not a commitment. The one approved option invites a real comparison.
Brexpiprazole (Rexulti) is the only drug the FDA has approved for agitation associated with Alzheimer's dementia, cleared in 2023 on two 12-week placebo-controlled studies. Per the FDA's approval announcement, it carries the antipsychotic class boxed warning: elderly patients with dementia-related psychosis treated with antipsychotics face an increased risk of death. So the choice is not between a risky experiment and a safe standard. It is between an unapproved agent with a small, federally monitored safety record and an approved one whose label states an increased risk of death. That framing is the honest one to bring to a parent's physician.
Who is legally allowed to enroll a parent
Federal research rules at 45 CFR 46.116 require legally effective informed consent from the subject or the subject's legally authorized representative before enrollment, and 46.117 permits the representative to sign the consent form. Being the adult child who handles everything is not, by itself, that authority. It has to be documented.
Who qualifies as a legally authorized representative depends on the law of the jurisdiction where the research is conducted. Under the 2018 Common Rule, an institution's own policy may designate one where no law addresses the question, which the HHS Office for Human Research Protections informed consent FAQs explain. The practical consequence: eligibility to consent varies by state and by site, and two hospitals running the same protocol can reach different answers about the same family. Before you contact a site, assemble the paperwork:.
- Durable power of attorney for health care, or the equivalent instrument in your state
- Guardianship or conservatorship order, if one exists
- Any written advance directive stating your parent's wishes about research
- Documentation of a prior expression of willingness to participate, made while your parent had capacity
The study partner role you would be taking on
LiBBY was run across multiple U.S. sites by the Alzheimer's Clinical Trial Consortium and funded primarily by the National Institute on Aging, which means its protocol and safety monitoring were federally overseen rather than managed by a sponsor alone. That structure is a reason for some confidence in the reporting, and it is worth confirming for whichever trial you are offered. It also shapes what the family commits to.
The National Institute on Aging advises asking, before enrolling, what the study is trying to find out, how it differs from standard medical care, and what the risks and side effects are. It also notes that inclusion criteria may require a study partner who accompanies the participant — in practice, the adult child. A study partner reports symptoms, tracks dosing, and attends visits, which for a hospice-eligible parent may mean travel that is itself burdensome. If you cannot reliably fill that role, say so at screening rather than mid-trial.
Frequently Asked Questions
Does a positive Phase 2 result mean the drug will be approved?
No. Phase 2 tests whether an effect exists in a small group; approval normally requires larger Phase 3 trials. LiBBY's 120 participants were enough to meet its endpoint, not enough to settle safety.
Can we get the THC/CBD combination outside a trial?
Not as a dementia agitation treatment. No THC/CBD product is FDA-approved for that use, so the specific T2:C100 formulation studied is available only through research.
Our parent is in moderate dementia, not hospice. Does LiBBY apply?
Not directly. Enrollment required hospice eligibility and clinical agitation, so both the benefit and the safety numbers describe late-stage, end-of-life patients.
What if our parent never said anything about research before losing capacity?
Ask the site how its institution handles that. Under the 2018 Common Rule, an institution's policy may designate a legally authorized representative where state law is silent — so the answer is site-specific, and the site's IRB, not the family, decides it.
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