VANCOUVER—Anecdotal reports, patient surveys, and studies have suggested that cannabis may help treat motor and nonmotor symptoms of Parkinson’s disease. Two studies presented at the 21st International Congress of Parkinson’s Disease and Movement Disorders further explored this possibility and assessed the effects of oral cannabidiol (CBD) and inhaled cannabis in patients with Parkinson’s disease.
Maureen A. Leehey, MD, Professor of Neurology and Chief of the Movement Disorders Division at the University of Colorado in Aurora, and colleagues conducted a phase II, open-label, dose-escalation study to evaluate the safety and tolerability of CBD (Epidiolex) in Parkinson’s disease. In addition, the researchers looked at secondary efficacy measures, including change in tremor, cognition, anxiety, psychosis, sleep, daytime sleepiness, mood, fatigue, and pain.
The researchers enrolled 13 patients who had a rest tremor amplitude score of 2 or greater on item 3.17 of the Unified Parkinson’s Disease Rating Scale (UPDRS). They excluded patients who had taken cannabinoids in the previous 30 days or had a history of drug or alcohol dependence.
Over a 31-day treatment period, patients received 5-, 7.5-, 10-, 15-, and 20-mg/kg/day doses of CBD. They received the highest dose on days 17–31. Patients had clinic visits at screening, baseline, and after the 31-day treatment period. Of the 13 patients enrolled, one failed the screening visit, another patient did not start the study drug, and another patient was on the study drug for two days. The 10 remaining patients were included in the adverse events analysis. Adverse events were mostly mild to moderate and included fatigue, diarrhea, somnolence, elevated liver enzymes, and dizziness. Three of the 10 patients dropped out of the study due to intolerance. One of the three patients had an allergic reaction and two had abdominal pain. There were no serious adverse events.
Among the seven patients who completed the treatment period and were included in the efficacy analysis, mean total UPDRS score significantly decreased from 45.9 at baseline to 36.4 at the final visit. UPDRS motor score significantly decreased from 27.3 to 20.3. Mean rigidity subscore significantly decreased from 9.14 to 6.29. In addition, data hinted that CBD treatment might have reduced pain and irritability, the researchers said.
These preliminary results indicate that CBD is tolerated, safe, and has beneficial effects in Parkinson’s disease, Dr. Leehey and colleagues said. The investigators next plan to conduct a crossover, double-blind, randomized controlled trial with 50 subjects.
Laurie K. Mischley, ND, PhD, MPH, Associate Clinical Investigator at Bastyr University Research Institute in Kenmore, Washington, and colleagues evaluated the effect of inhaled cannabis on Parkinson’s disease tremor using motion sensors and qualitative interviews.
The study included patients with Parkinson’s disease who used cannabis in the state of Washington. Patients wore a movement monitor for two weeks and logged their cannabis use in a journal. Sensors recorded the frequency and amplitude of tremor during waking hours, and participants pressed a button on the motion sensor every time they used cannabis. The researchers compared tremor duration and magnitude in the hour before and after inhaled cannabis use. After two weeks, interviewers asked participants standardized, open-ended, nonleading questions about their perception of the effects of cannabis on their symptoms.
The 10 patients for whom they had data had a mean age of 60 (range, 40 to 74) and a mean time since diagnosis of 6.3 years. Among four participants who had more than 10 cannabis exposures and a measurable tremor more than 2% of the time in the hour before cannabis use during the study, the percent of the time with detected tremor significantly decreased in the hour after use. Sensor data suggested that tremor reduction may have been sustained for three hours after exposure to cannabis, the researchers said. “In those with a persistent tremor, there was a consistent decrease in the tremor persistence and in detected tremor magnitude following cannabis use,” the investigators said.
During the follow-up interview, nine of the 10 participants thought that cannabis helped their symptoms, and one patient thought it worsened symptoms. “The one participant who reported cannabis worsening symptoms specifically described, ‘sometimes it speeds up the tremor at the start’ but ‘then it relaxes it,’” the researchers said.
Side effects reported by patients included sleepiness, sluggishness, concerns about social stigma and driving, short-term memory, and dry throat.
“Improved sleep was an unsolicited theme during the qualitative interviews, with 60% of individuals reporting improvements,” Dr. Mischley and colleagues said. “The qualitative interviews suggest patients perceive cannabis to have therapeutic potential for Parkinson’s disease symptom management. These data suggest further investigation of cannabis for impaired sleep is warranted.”
The researchers noted that most subjects had a mild, intermittent tremor that was not reliably detected by the motion sensors. Future studies should enroll subjects with more pronounced tremor and use consistent cannabis strains, doses, and delivery systems, they said.
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