With medicinal cannabis now legalized in many parts of the world, there is growing interest in its use to alleviate symptoms of many illnesses including Parkinson's disease (PD).
According to results of a survey of PD patients in Germany in the Journal of Parkinson's Disease, more than 8% of patients with PD reported using cannabis products and more than half of those users (54%) reported a beneficial clinical effect.
Cannabis products containing THC (tetrahydrocannabinol, the main psychoactive compound of cannabis) can be prescribed in Germany when previous therapies are unsuccessful or not tolerated, and where cannabis can be expected with not a very unlikely chance to relieve disabling symptoms. CBD (pure cannabidiol, derived directly from the hemp plant, a cousin of the marijuana plant) is available without a prescription from pharmacies and on the internet.
"Medical cannabis was legally approved in Germany in 2017 when approval was given for therapy-resistant symptoms in severely affected patients independent of diagnosis and without clinical evidence-based data," explained lead investigator Prof. Dr. med. Carsten Buhmann, Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. "PD patients fulfilling these criteria are entitled to be prescribed medical cannabis, but there are few data about which type of cannabinoid and which route of administration might be promising for which PD patient and which symptoms. We also lack information about the extent to which the PD community is informed about medicinal cannabis and whether they have tried cannabis and, if so, with what result."
Investigators aimed to assess patient perceptions of medicinal cannabis as well as evaluate the experiences of patients already using cannabis products. They performed a nationwide, cross-sectional, questionnaire-based survey among members of the German Parkinson Association (Deutsche Parkinson Vereinigung e.V.), which is the largest consortium of PD patients in German-speaking countries with nearly 21,000 members. Questionnaires were sent out in April 2019 with the association's membership journal and were also distributed in the investigators' clinic.
Over 1,300 questionnaires were analyzed; results showed that interest in the PD community in medical cannabis was high, but knowledge about different types of products was limited. Fifty-one percent of respondents were aware of the legality of medicinal cannabis, and 28% were aware of the various routes of administration (inhaling versus oral administration), but only 9% were aware of the difference between THC and CBD.
More than 8% of patients were already using cannabinoids and more than half of these users (54%) reported that it had a beneficial clinical effect. The overall tolerability was good. Over 40% of users reported that it helped manage pain and muscle cramps, and more than 20% of users reported a reduction of stiffness (akinesia), freezing, tremor, depression, anxiety, and restless legs. Patients reported that inhaled cannabis products containing THC were more efficient in treating stiffness than oral products containing CBD but were slightly less well tolerated.
Patients using cannabis tended to be younger, living in large cities, and more aware of the legal and clinical aspects of medicinal cannabis. Sixty-five percent of non-users were interested in using medicinal cannabis, but lack of knowledge and fear of side effects were reported as main reasons for not trying it.
"Our data confirm that PD patients have a high interest in treatment with medicinal cannabis but lacked knowledge about how to take it and especially the differences between the two main cannabinoids, THC and CBD," noted Prof. Dr. med. Buhmann. "Physicians should consider these aspects when advising their patients about treatment with medicinal cannabis. The data reported here may help physicians decide which patients could benefit, which symptoms could be addressed, and which type of cannabinoid and route of administration might be suitable."
"Cannabis intake might be related to a placebo effect because of high patient expectations and conditioning, but even that can be considered as a therapeutic effect. It has to be stressed, though, that our findings are based on subjective patient reports and that clinically appropriate studies are urgently needed," he concluded.
Bastiaan R. Bloem, MD, PhD, Director, Radboudumc Center of Expertise for Parkinson & Movement Disorders, Nijmegen, The Netherlands, and Co-Editor-in Chief of the Journal of Parkinson's Disease, added, "These findings are interesting in that they confirm a widespread interest among patients in the use of cannabis as a potential treatment for people living with PD. It is important to emphasize that more research is needed before cannabis can be prescribed as a treatment, and that guidelines currently recommend against the use of cannabis, even as self-medication, because the efficacy is not well established, and because there are safety concerns (adverse effects include among others sedation and hallucinations). As such, the present paper mainly serves to emphasize the need for carefully controlled clinical trials to further establish both the efficacy and safety of cannabis treatment."