The study aims to evaluate medical cannabis’ (MC) efficacy and adverse effects (AE) in treatment of Parkinson’s disease (PD) symptoms.

Thirty U.S. states have legislation allowing prescription of medical cannabis (MC).  Previous research suggests possible benefits of cannabinoids in treating PD symptoms including tremor, rigidity and dyskinesia; however more research is needed.

A retrospective analysis including patients diagnosed with idiopathic PD and treated with MC through the NYS Medical Marijuana Program was conducted. 

Sixty-two (43=Male, 20=Female) patients aged 71±10 years were included. Primary indication for MC treatment included PD (71%), chronic pain (25%), cancer (2%), and neuropathy (2%).  Seventy-seven percent (N=48) reported improvement in PD motor symptoms, most commonly in tremor and spasticity; improvements in rigidity, gait instability, dyskinesia and bradykinesia were also noted. Of patients reporting chronic pain, 85% reported decreased pain with MC therapy. Twenty-five patients were taking an opioid at MC therapy initiation, and a significant proportion (48%, p=0.002) either discontinued or reduced the opioid during treatment. Over half of patients also reported improvement in non-motor PD symptoms, including sleep disturbance, anxiety, depressed mood, and nausea. Forty-four percent of patients reported AE, most commonly somnolence (N=15), followed by disorientation (N=8) and dizziness (N=4). AE were transient or resolved with dose adjustment in 41% of these patients. MC was tolerated well in this population, with only 4 patients (6.4%) discontinuing due to AE.

The study finds that, typically in combination with other PD therapies, MC is a well-tolerated option to improve both motor and non-motor symptoms in PD patients, and may be helpful in relieving some AE of PD medications such as nausea or insomnia.  Commonly observed side effects of MC included somnolence and dizziness.  Future randomized placebo-controlled trials are necessary to verify efficacy, AE profiles, dosage information, and long-term effects of MC on PD.