Cannabinoids for treatment of spasticity and other symptoms related to multiple sclerosis (CAMS study): multicentre randomised placebo-controlled trial

Background Multiple sclerosis is associated with muscle stiffness, spasms, pain, and tremor. Much anecdotal evidence suggests that cannabinoids could help these symptoms. Our aim was to test the notion that cannabinoids have a beneficial effect on spasticity and other symptoms related to multiple sclerosis. Methods We did a randomised, placebo-controlled trial, to which we enrolled 667 patients with stable multiple sclerosis and muscle spasticity. 630 participants were treated at 33 UK centres with oral cannabis extract (n=211), Δ9-tetrahydrocannabinol (Δ9-THC; n=206), or placebo (n=213). Trial duration was 15 weeks. Our primary outcome measure was change in overall spasticity scores, using the Ashworth scale. Analysis was by intention to treat. Findings 611 of 630 patients were followed up for the primary endpoint. We noted no treatment effect of cannabinoids on the primary outcome (p=0•40). The estimated difference in mean reduction in total Ashworth score for participants taking cannabis extract compared with placebo was 0•32 (95% CI −1•04 to 1•67), and for those taking Δ9-THC versus placebo it was 0•94 (−0•44 to 2•31). There was evidence of a treatment effect on patient-reported spasticity and pain (p=0•003), with improvement in spasticity reported in 61% (n=121, 95% CI 54•6–68•2), 60% (n=108, 52•5–66•8), and 46% (n=91, 39•0–52•9) of participants on cannabis extract, Δ9-THC, and placebo, respectively. Interpretation Treatment with cannabinoids did not have a beneficial effect on spasticity when assessed with the Ashworth scale. However, though there was a degree of unmasking among the patients in the active treatment groups, objective improvement in mobility and patientsʹ opinion of an improvement in pain suggest cannabinoids might be clinically useful.