A phase 2 randomized trial in Brazil found that an oral CBD-dominant cannabis oil did not reduce chronic pain in people with Parkinson’s disease more than placebo, according to a NeurologyLive report on the study, published in Movement Disorders.

Of 101 adults randomized, 87 completed the nine-week trial, which stopped early after a planned futility analysis. Other non-motor symptom measures also showed no significant differences. The oil was generally well tolerated, though irritability was more common with active treatment.

The report lists a low THC dose of about 1 mg daily, a strong placebo response, short follow-up and a single study site as possible limitations. The authors called for larger trials at higher doses. The findings apply only to this formulation and population.