A Systematic Review of the Effectiveness of Medical Cannabis for Psychiatric, Movement and Neurodegenerative Disorders

Summary & key facts

Researchers collected about two dozen carefully controlled studies that tested medical cannabis for psychiatric, movement and brain-degeneration problems. Some studies showed benefits for conditions such as anorexia, anxiety, PTSD, certain psychotic symptoms, agitation in dementia, Huntington’s disease, Tourette’s syndrome, and involuntary movement in Parkinson’s. But most of those studies were small or poorly run, so the reviewers said we can’t be sure the benefits are real. There was little or no evidence for amyotrophic lateral sclerosis (ALS) and dystonia. The reviewers called for larger, better trials that check both short-term and long-term effects and safety.

Key facts:

• The authors searched major medical databases for carefully controlled trials of cannabis and its chemical relatives, and they included about 24 reports in their review.
• Those studies covered many conditions, including anorexia nervosa, anxiety, post-traumatic stress disorder (PTSD), psychotic symptoms, agitation in Alzheimer’s and dementia, Huntington’s disease, Parkinson’s disease movement problems, and Tourette syndrome.
• Some individual trials reported positive results for problems like anxiety, PTSD, anorexia, agitation in dementia, psychotic symptoms, Huntington’s disease, Tourette’s syndrome, and involuntary movements in Parkinson’s disease.
• Overall, the reviewers said the evidence is low quality because many trials were small and had unclear or weak methods, such as not clearly explaining how people were assigned to treatments and whether patients and doctors were kept unaware of who got cannabis.
• The review found little or no trial evidence that cannabis helps amyotrophic lateral sclerosis (ALS) or dystonia.
• Because of the low quality and small sizes of the trials, the reviewers recommended more large, well-run studies to test whether medical cannabis really works, how safe it is, and how it might help the brain.

Abstract

The discovery of endocannabinoid's role within the central nervous system and its potential therapeutic benefits have brought forth rising interest in the use of cannabis for medical purposes. The present review aimed to synthesize and evaluate the available evidences on the efficacy of cannabis and its derivatives for psychiatric, neurodegenerative and movement disorders. A systematic search of randomized controlled trials of cannabis and its derivatives were conducted via databases (PubMed, Embase and the Cochrane Central Register of Controlled Trials). A total of 24 reports that evaluated the use of medical cannabis for Alzheimer's disease, anorexia nervosa, anxiety, dementia, dystonia, Huntington's disease, Parkinson's disease, post-traumatic stress disorder (PTSD), psychosis and Tourette syndrome were included in this review. Trial quality was assessed with the Cochrane risk of bias tool. There is a lack of evidence on the therapeutic effects of cannabinoids for amyotrophic lateral sclerosis and dystonia. Although trials with positive findings were identified for anorexia nervosa, anxiety, PTSD, psychotic symptoms, agitation in Alzheimer's disease and dementia, Huntington's disease, and Tourette syndrome, and dyskinesia in Parkinson's disease, definitive conclusion on its efficacy could not be drawn. Evaluation of these low-quality trials, as rated on the Cochrane risk of bias tools, was challenged by methodological issues such as inadequate description of allocation concealment, blinding and underpowered sample size. More adequately powered controlled trials that examine the long and short term efficacy, safety and tolerability of cannabis for medical use, and the mechanisms underpinning the therapeutic potential are warranted.

Topics

Cannabis and Cannabinoid Research Prenatal Substance Exposure Effects Sleep and Wakefulness Research

Categories

Health Sciences Medicine Pharmacology

Tags

Cannabis Disease Medical cannabis Medicine Movement disorders Pathology Psychiatry

Substances

Cannabis medical cannabis

Conditions & symptoms

Anxiety Eating Disorder PTSD Anxiety or worry Poor appetite or overeating