Do CBD-to-THC Ratios in Cannabis Impact Symptom Control in Dementia?

PostedMarch 11, 2026

UpdatedMarch 11, 2026

ByMy Patient Advice

Author: Julia Sutton, MSc | Reviewed by: Dr. Clarissa Morton, PharmD

The potential of cannabis-based treatments for dementia has sparked interest, particularly in the CBD-to-THC ratio. Different ratios of cannabidiol (CBD) and tetrahydrocannabinol (THC) are thought to impact the severity and range of symptoms experienced by dementia patients. But does the ratio really affect symptom control, particularly for agitation and anxiety?

What The Research Shows

Research shows that CBD is non-psychoactive and is believed to have calming, anti-inflammatory properties, while THC is psychoactive and may help with sleep and appetite but can also cause confusion or agitation in higher doses.

A 2019 trial published in The Lancet compared CBD-to-THC ratios and their impact on agitation and behaviour in dementia. The study found that a balanced 1:1 ratio of CBD to THC was most effective in reducing agitation without excessive side effects. However, higher doses of THC alone led to increased confusion and aggression in participants.

Another study published in Frontiers in Neurology in 2020 also supported these findings, suggesting that low doses of THC with higher CBD content might be optimal for symptom control, especially in people with Alzheimer’s disease. However, the evidence remains inconclusive, with many studies still in early stages and limited by sample size and duration.

What The Guidelines Say

According to NICE guidance NG144 (updated 2025), cannabis-based medicinal products (CBMPs) should not be prescribed for behavioural symptoms of dementia, including agitation and aggression, outside of clinical trials. The World Health Organization (WHO) reviewed CBD in 2017 but has not endorsed cannabis products for dementia care.

Expert Commentary

Experts, including those at the Royal College of Psychiatrists, recommend that cannabis-based treatments, including CBD-to-THC ratios, be used only within controlled research environments.

Clinical Bottom Line

Balanced CBD-to-THC ratios, such as 1:1, may help reduce agitation in dementia.

Higher THC doses can cause confusion and aggression, particularly in frail or elderly patients.

Evidence for optimal CBD-to-THC ratios is still limited and inconclusive.

NICE and NHS recommend using cannabis-based products only within clinical research settings.

More large-scale studies are needed to confirm the ideal ratios for symptom management.

About AlleviMed

If you are considering whether medical cannabis could be appropriate for a loved one with Dementia, AlleviMed offers private eligibility consultations across the UK. The service connects families with GMC-registered specialists for safe, compliant advice on evidence-based cannabis treatments. You can learn more at allevimed.co.uk once the site is live.

Takeaway

While CBD-to-THC ratios have shown promise in managing agitation and anxiety in dementia, further high-quality research is needed to establish the most effective ratio for symptom control. NICE and NHS guidelines advise that such products should not be used outside of regulated clinical trials until more definitive evidence is available.

Julia Sutton, MSc

Author

Julia Sutton is a clinical psychologist with a Master’s in Clinical Psychology and experience providing psychological assessment and therapy to adolescents and adults. Skilled in CBT, client-centered therapy, and evidence-based interventions, she has worked with conditions including depression, anxiety, bipolar disorder, and conversion disorder. She also has experience in child psychology, conducting psycho-educational evaluations and developing tailored treatment plans to improve learning and well-being.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the author's privacy.

Dr. Clarissa Morton, PharmD

Reviewer

Dr. Clarissa Morton is a licensed pharmacist with a Doctor of Pharmacy degree and experience across hospital, community, and industrial pharmacy. She has worked in emergency, outpatient, and inpatient pharmacy settings, providing patient counseling, dispensing medications, and ensuring regulatory compliance. Alongside her pharmacy expertise, she has worked as a Support Plan & Risk Assessment (SPRA) officer and in medical coding, applying knowledge of medical terminology, EMIS, and SystmOne software to deliver accurate, compliant healthcare documentation. Her skills span medication safety, regulatory standards, healthcare data management, and statistical reporting.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the reviewers's privacy.