Nearly half of Parkinson's disease patients who have tried marijuana say the drug helped relieve their symptoms, according to a survey of patients with the degenerative neurological disorder.  Dr. Evzin Ruzicka, an attending neurologist at Charles University in Prague in the Czech Republic, reported the findings here at the Movement Disorders Society's Seventh International Congress of Parkinson's Disease and Movement Disorders. Ruzicka is also a consultant at the Prague Movement Disorders Center.  "It's difficult to directly study the medical effects of cannabis in the Czech Republic, where we conducted our research, because of its illegal status," Ruzicka told Reuters Health. "Therefore, we had to conduct anonymous surveys. To our knowledge, this is the first study to assess the effect of cannabis on Parkinson's disease, and our findings suggest it may alleviate some symptoms."  Ruzicka and his colleagues chose to investigate marijuana's effects on Parkinson's disease after hearing from several patients that they had tried the drug and it had helped them.

The investigators asked all patients who were treated for Parkinson's disease at their center to complete a questionnaire that asked about cannabis use and about several Parkinson's disease symptoms, including overall symptoms; tremor while at rest; bradykinesia, or slow movement; muscle rigidity; and dyskinesias, or involuntary movements.  Dyskinesias are caused by levodopa, the mainstay medication in Parkinson's treatment.  Among the 630 patients to whom the investigators sent questionnaires, 339 (54%) returned them.  Among the responders, 25% reported that they had used cannabis. Most had used it orally, either as fresh or dried leaves.  Within this group, 39 patients (46%) reported that their Parkinson's disease symptoms in general were relieved after they started using cannabis.

The respondents reported that the improvement in symptoms occurred an average of 1.7 months after they had started using cannabis. Patients who used it for at least three months were more likely to experience symptom relief than those with shorter experience, the investigators reported.   This delay between the beginning of cannabis use and the relief of symptoms made it unlikely that the respondents were having a placebo effect, Ruzicka said.  They found no relationship between the length of cannabis use and the effect on involuntary movements. However, daily marijuana users reported more improvement in their dyskinesias than those using it less often.  The investigators speculated that the effect of cannabis on Parkinson's disease symptoms may be due to interaction among cannabis, certain brain receptors that respond to cannabis and endogenous cannabinoids or cannabis-like substances within the body.