RCTs on Cannabinoids for Movement Disorders Show Mixed Results Across Conditions | Research

The takeaway

A systematic review of randomized trials found cannabinoids improved tics in Tourette syndrome and quality of life in Parkinson's, but showed no benefit for dystonia and limited evidence for Huntington's disease.

Neurologists treating movement disorders; patients with Parkinson's, Tourette syndrome, or Huntington's considering cannabis; clinical trial designers.

Both Tourette RCTs showed tic improvement; neither dystonia RCT showed benefit

What the researchers found

In Parkinson's disease, no RCT showed motor symptom improvement, though nabilone improved quality of life and reduced dyskinesia in one trial. Both Tourette syndrome RCTs showed tic improvement. Only one of three Huntington's disease RCTs found symptom relief. Neither dystonia RCT showed benefit.

Why it matters

Movement disorders are often difficult to treat, and patients frequently ask about cannabis. This review provides an evidence-based summary of what RCTs actually show, which is considerably more nuanced than anecdotal reports suggest.

The numbers in context

7 PD RCTs: none showed motor improvement, 1 showed nabilone improved quality of life, 1 showed nabilone reduced dyskinesia, 1 showed CBD reduced anxiety and tremor. 2 Tourette RCTs: both showed tic improvement. 3 HD RCTs: 1 showed nabilone symptom relief. 2 dystonia RCTs: no benefit.

How the study worked

Systematic review of all published randomized controlled trials on cannabinoids in movement disorders. Identified 7 RCTs on Parkinson's disease, 2 on Tourette syndrome, 3 on Huntington's disease, and 2 on dystonia. Different cannabis formulations were used across studies.

What this study cannot tell us

The total number of RCTs is small, and the trials themselves had small sample sizes. Different cannabinoid formulations were used across studies, making comparison difficult. Publication bias may favor positive results.

How to read the evidence

Moderate: systematic review of RCTs (highest-quality study design), but the included trials are few, small, and heterogeneous.

When this study was published

Published in 2022.

The bigger picture

The pattern across conditions is telling: cannabinoids seem most promising for Tourette syndrome and some non-motor symptoms of Parkinson's, but the small number and size of trials make definitive conclusions impossible. The authors emphasize the urgent need for better-designed trials.

Questions still open

Would larger, standardized RCTs confirm the Tourette syndrome findings? Which specific cannabinoid formulations are most promising for each movement disorder? Why do cannabinoids appear to help with some symptoms (tics, quality of life) but not core motor deficits?

Common questions

Does cannabis help with Parkinson's disease?

No RCT showed improvement in core motor symptoms of Parkinson's. However, one trial found nabilone improved quality of life, one showed reduced dyskinesia, and one found CBD reduced anxiety-related tremor. The evidence does not support cannabis for motor symptoms.

Which movement disorder has the strongest evidence for cannabinoids?

Tourette syndrome, where both available RCTs showed improvement in tics. However, these were small trials, and larger studies are needed before firm recommendations can be made.

Read the original research

Randomized controlled trials on the use of cannabis-based medicines in movement disorders: a systematic review.

Journal of neural transmission (Vienna, Austria : 1996), 129(10), 1247-1256

View on PubMed ↗Publisher’s paper ↗

Citation

Oikonomou, P; Jost, W H. (2022). Randomized controlled trials on the use of cannabis-based medicines in movement disorders: a systematic review.. Journal of neural transmission (Vienna, Austria : 1996), 129(10), 1247-1256. https://doi.org/10.1007/s00702-022-02529-x