Part 1 of 1
The Medical Use of Marijuana in Amyotrophic Lateral Sclerosis
Amyotrophic lateral sclerosis (ALS) is the most common form of adult motor neuron disease. Although there is phenotypic variability and heterogeneity, ALS is primarily characterized by selective degeneration of motor neurons located in the primary motor cortex, spinal cord and brainstem, resulting in progressive muscle weakness and atrophy, with death typically due to respiratory failure within 2 to 5 years of symptom onset. Currently, there is no effective therapy to meaningfully extend survival but ongoing elucidation of the pathophysiology is resulting in continuously emerging targets and treatments for study in clinical trials. To date, only one medication has been shown to slow disease progression: FDA approved anti-glutamatergic agent Riluzole, which has only modest efficacy (Miller et al. 2007, Miller et al. 2012). Current treatments are aimed at symptom management, and include maintenance of adequate nutrition, use of non-invasive ventilatory support and airway clearance techniques (Miller et al., 2009). Symptoms such as pain, muscle cramps, spasticity, anorexia, wasting, dyspnea, sialorrhea, anxiety and depression may be present and severely affect function and quality of life.
Based on the known pathophysiology of ALS, cannabinoids appear as good potential therapeutic candidates both from a symptom management and disease modifying perspective, due to the multiplicity of cannabinoid actions, including anti-inflammatory, neuroprotective and immunomodulatory properties (Gowran et al. 2011, Karam et al. 2014, Velayudhan et al. 2014). Preclinical studies strongly suggest that the endocannabinoid system is involved in the pathophysiology of ALS and may have significant neuroprotective and disease-modifying effects in ALS (Pryce and Baker 2015). However, despite a previous call for clinical trials (Carter et al. 2010) and preclinical evidence indicating that cannabis-based medicines could potentially treat ALS, very few clinical investigations have been conducted. This module will review the available clinical evidence for the use of cannabis in treatment of ALS disease and associated symptoms.