Smoking cannabis is better than placebo at reducing spasticity in patients with multiple sclerosis with treatment resistant spasticity. In a study of 30 patients, daily assessments were made before and after treatment, with a washout interval of 11 days before patients crossed over to the other group. Spasticity improved significantly, but scores for “timed walks” did not (CMAJ 2012;184:1143-50, doi:10.1503/cmaj.110837). Although well tolerated, smoking cannabis caused acute cognitive effects, and the team plans to test whether lower doses will have similar benefits but with a reduced cognitive effect.

Using electric fans in heatwaves may inadvertently cause more harm than good, but no available research on the subject has met Cochrane requirements, resulting in conclusions that cannot support or refute their use (Cochrane Database of Systematic Reviews 2012;7, doi:10.1002/14651858.CD009888). Fans could help increase heat loss if the temperature is below 35°C and the fan is …