The synthetic Δ9-tetrahydrocannabinol (THC) analogue nabilone, also sold by the trade name Cesamet, was recently evaluated for the potential to treat symptoms of Parkinson’s disease (PD).  Parkinson’s disease symptoms consist of motor symptoms such as tremors and rigidity , and non-motor symptoms such as a loss of smell, trouble sleeping, or autonomic nervous system dysfunction.  Severe non-motor symptoms (NMS) significantly decrease the quality of life for people who suffer with PD. 
Researchers in Austria hypothesized that cannabinoids may be a possible treatment option for non-motor symptoms of PD because the endocannabinoid system (ECS) plays an integral role in regulating non-motor functions such as sleep, pain, mood, and eating.  The synthetic cannabinoid nabilone acts as a partial agonist on cannabinoid receptors 1 and 2 in the same way that Δ9-THC acts on these receptors.  However, compared to THC, nabilone has more predictable side effects and is less psychoactive. 
The study’s goal was to evaluate the safety and efficacy of nabilone in patients suffering from severe NMS from PD. The researchers designed a randomized, placebo-controlled, double-blind, parallel group trial. The study was divided into two phases. Phase one of the trial consisted of nabilone dose optimization to determine the ideal dose for each participant. Each subject was first given a 0.25 milligram (mg) dose of nabilone and the dose was increased over time until the patients noted improvement of NMS. Phase two divided the participants into two groups: one group received their optimal dose of nabilone developed in phase one, and the other group received a placebo pill. Patients were monitored throughout a four-week period and were surveyed upon completion.
There were very few adverse effects experienced by any participants in the study. The most prominent adverse effects were fatigue, dizziness, dry mouth, and sleepiness.  Twice as many participants in the placebo group noted their symptoms worsened during phase two of this study compared to the nabilone group.  The nabilone group showed significant improvement in nighttime sleep problems and feelings of anxiety which the placebo group did not experience. Further, researchers noted promise in the efficacy of nabilone in relieving NMS in patients at low doses around one milligram.
Further investigation with a larger and more diverse subject group will be needed before any conclusions can be made regarding cannabinoids and the treatment of non-motor symptoms of Parkinson’s disease.
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