The effects of Cannabis on hallucinations in Parkinson's disease patients

Cannabis use is on the rise both as medical treatment and recreational use. There is evidence that cannabis can cause hallucinations and psychosis especially with heavy and prolonged use. Parkinson's disease (PD) carries an increased risk for development of hallucinations and psychosis. It is possible that cannabis may exacerbate this risk and result in earlier and greater amounts of hallucinations and psychosis in this vulnerable population. A literature review was performed to determine the answer to that question. Two articles were found which listed the incidence of hallucinations and delusions during the use of cannabis in PD patients. 21.3% or 10 out of 47 patients reported development of hallucinations while treated with cannabis and 2.8% developed delusions. While these numbers are within the range of prevalence of hallucinations and psychosis in PD, the number of studies and patients evaluated are too small to make any definite conclusions pointing to the need for more research in this area.