Can Cannabinoids Treat Obsessive-Compulsive Disorder?
A growing body of medical research shows that the endocannabinoid system (ECS) can play a role in modulating anxiety, fear, and repetitive behaviors. But can it do the same for obsessive-compulsive disorder and its symptoms? And if so, could cannabis-based medicine be a novel, yet effective treatment for the condition?
In a new review article, published in Cannabis and Cannabinoid Research, researchers from Columbia University and the Weill Cornell Medical College in New York have examined this possibility.
In their comprehensive report, the team provide an overview of the complex workings of the ECS, and examine the evidence gathered from animal and human studies that imply that the ECS may play a role in obsessive-compulsive disorder and related disorders.
“Is there a place for cannabinoid-based medicines in psychiatry?” asks Daniele Piomelli, PhD, the editor-in-chief of Cannabis and Cannabinoid Research.
“Evidence from animal and human studies points to the endocannabinoid system as an important regulator of emotionality, but how can we exploit this knowledge for therapy? This review article offers a critical assessment of the evidence, focused on obsessive compulsive disorder, and clues to future research.”
What is obsessive-compulsive disorder?
Obsessive-compulsive disorder (OCD) is predominantly characterized by frequent intrusive obsessive thoughts and repetitive behaviors, such that they become significantly time consuming, distressing, or present an impairment to ordinary function. People with OCD can also experience intense feelings of anxiety, which drives the cycle of obsession and compulsive behavior.
Treatments do exist to combat the effects of OCD, though the exact treatment given will depend on how severely the disorder affects the patient’s life. Most commonly, OCD suffers will undergo some form of psychological therapy and/or start a course of antidepressant medication to help deal with symptoms.
However, it can take several months for these treatments to become effective, if they work at all. The medication can also result in significant side effects, such as insomnia, dizziness, headaches, distorted vision, and in some cases even suicidal thoughts. As a result, there is an interest in developing novel treatments for OCD.
This is where the ECS comes in. The authors of the new review note that in the same regions of the brain and central nervous system that have been implicated in OCD, you can also find CB1 cannabinoid receptors. CB1R is the major receptor of the ECS, and so it can be inferred that its presence means that there will also be ECS activity in that region.
Promising early evidence from animal and human trials
Given this overlap in OCD-relevant neural circuitry, several animal and human studies have been done to evaluate the effect that the administration of cannabinoids and the resultant modulation of the endocannabinoid system might have on repetitive behavior, and on other symptoms of OCD. These are the studies that form the backbone of the new review piece.
From their review of relevant animal studies, the researchers ascertained that CB1R agonists can have an anti-anxiety effect when given at specific dosages, as can the metabolic enzymes of the ECS. Modulation of the metabolic enzymes was also linked to a decreased responsiveness to stress and the facilitation of fear extinction. In relation to repetitive behavior, the researchers found several rodent studies that linked the ECS to habit learning and repetitive behavior through CB1R activity. Insufficient CB1R activity, the studies concluded, might lead to a dependence on previously learned behaviors and habits.
In the data from the human clinical studies, the researchers also found evidence that CBR1 agonists (such as dronabinol and other THC analogs) as well as cannabidiol (CBD) were of use in curbing anxiety and enhancing the extinction of fear memories in healthy adults. Survey data from investigations into the effects of cannabis on patients with Tourette syndrome also suggested a link between the ingestion of cannabinoids and the reduction of motor tics and the urge to perform compulsive behaviors.
Cannabinoids as a treatment for OCD
The researchers were able to find only three case studies that directly dealt with OCD and the effects of cannabinoids on its symptoms.
In the first case, a 38-year-old woman who was diagnosed with major depression and OCD was administered dronabinol after failing to respond to other courses of treatment, but who had anecdotally reported that smoking cannabis had previously relieved her symptoms. Within 10 days of first taking dronabinol, the woman’s score on the Yale-Brown Obsessive Compulsive Scale (YBOCS), which assesses the severity of illness in patients with OCD, had dropped from a “moderate” 20 to a “mild” 10.
The second case concerned a 36-year-old man who had been hospitalized as his schizophrenia and OCD symptoms worsened. He had also failed to respond to other medical interventions and was given dronabinol in addition to his other antipsychotic medications. Within two weeks, the man’s YBOCS score dropped from 25 to 15, with no additional side effects or psychotic disturbances arising as a result of adding dronabinol to his treatment plan.
In the final case, a 24-year-old man had developed obsessive compulsive behavior following a stroke, and like the first two, had also responded poorly to conventional treatment. After his request for a neurological treatment was denied, the patient was given dronabinol. His score reportedly fell from 39 to 10 over the course of just two weeks, which enabled him to begin a course of therapy to further improve his condition.
These case studies, as well as the summation of the data from other human and animal studies, led the researchers to conclude their review in support of further investigation into the action of cannabinoids on OCD symptomology, as it appears that the cannabinoids could well be an effective novel treatment for the disorder.
The researchers encourage further clinical study of the field, highlighting that the type of cannabinoid agent being used to combat OCD symptoms could be an interesting route of future study, in terms of evaluating effectiveness but also side effect risk. As such it may be possible to improve on the effects of dronabinol that were reported in the three case studies. Further study into the mechanisms of the ECS and how this relates to OCD symptomology was also recommended.