Data from preclinical animal studies have implicated the endocannabinoid system in the pathophysiology of amyotrophic lateral sclerosis (ALS). In addition, exogenous cannabinoids have also been shown to slow down disease progression in ALS mice, likely via anti-oxidant, anti-inflammatory and neuroprotective effects (reviewed Carter et al. 2010). The jury is out on whether these beneficial effects translate from animal models to humans however, as large scale clinical trials designed to evaluate the efficacy of medicinal cannabis as a symptomatic treatment for ALS are lacking. Anecdotal reports and a few small-scale studies have reported cannabis use to moderately affect spasticity, pain, depression, appetite loss, and drooling (Amtmann et al. 2004). In a pilot study (n = 19), to investigate the safety and tolerability of THC in ALS patients, dronabinol (synthetic THC), was reported to be very well tolerated with symptomatic benefits seen in insomnia and appetite (Gelinas et al. 2002). In a small randomised, placebo-controlled, crossover trial, 5mg of oral THC bd was found to be well tolerated however, did not affect cramp frequency or intensity (Weber et al. 2010). Many limitations exist in these studies including short trial duration, small sample sizes and modest effect sizes.
Much of the more robust evidence for the anti-spasticity/cramping and analgesic effects of medicinal cannabis can be gleaned from clinical trials investigating the safety and efficacy of Sativex (a THC:CBD 1:1 ratio blend) for spasticity and pain symptoms in multiple sclerosis (MS). Sativex is currently approved in Canada and some European countries for muscle spasticity and neuropathic pain in MS.
The American Academy of Neurology recommends that clinicians may offer THC:CBD to reduce the symptoms of spasticity and pain, but should inform patients that it may not be effective for improving objective spasticity measures (Yadav et al 2014).
Products with a THC:CBD 1:1 ratio blend can be reviewed by Healthcare Practicioners on the Cannabis Access Clinics website.