The effect of cannabis on tremor in patients with multiple sclerosis.

Disabling tremor is common in patients with multiple sclerosis (MS). Data from animal model experiments and subjective and small objective studies involving patients suggest that cannabis may be an effective treatment for tremor associated with MS. To our knowledge, there are no published double-blind randomized controlled trials of cannabis as a treatment for tremor in MS patients. The authors conducted a randomized double-blind placebo-controlled crossover trial to examine the effect of oral cannador (cannabis extract) on 14 patients with MS with upper limb tremors. There were eight women and six men, with a mean age of 45 years and mean Expanded Disability Status Scale score of 6.25. Patients were randomly assigned to receive each treatment and the doses escalated over a 2-week period before each assessment. The primary outcome was change on a tremor index, measured using a validated tremor rating scale. The study was powered to detect a functionally significant 50% improvement in the tremor index. Secondary outcomes included accelerometry, an ataxia scale, spiral drawing, finger tapping, and nine-hole pegboard test performance. Analysis of the data showed no significant improvement in any of the objective measures of upper limb tremor with cannabis extract compared to placebo. Finger tapping was faster on placebo compared to cannabis extract (p < 0.02). However, there was a nonsignificant trend for patients to experience more subjective relief from their tremors while on cannabis extract compared to placebo. Cannabis extract does not produce a functionally significant improvement in MS-associated tremor.