Brain Stimulation May Treat Cannabis Use Disorder in People with Schizophrenia
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A non-invasive brain stimulation technique may help to reduce problematic cannabis use in people with schizophrenia, a new study led by the Centre for Addiction and Mental Health (CAMH) has found.
The study, published in the journal Schizophrenia, is the first to investigate the effects of repetitive transcranial magnetic stimulation (rTMS) on cannabis use disorder (CUD) in people with schizophrenia. It was supported by the US National Institute on Drug Abuse (NIDA) and the CAMH Foundation.
This kind of research is crucial, the CAMH researchers say, as people with schizophrenia and other mental illnesses are still no known effective treatments for CUD.
Cannabis use falls after brain stimulation
Brain stimulation technologies such as rTMS are primarily used for easing symptoms in people with treatment-resistant depression. However, recent studies have also suggested that stimulation treatment could be an effective avenue for tackling drug consumption and craving.
The rTMS technique is non-invasive and uses electromagnetic coils placed on the skull to deliver magnetic pulses to the brain. While the exact neurobiological mechanisms behind rTMS’ effectiveness are not completely understood, scientists do know that these magnetic pulses can stimulate activity in the nerve cells in certain brain regions.
In this double-blind, controlled randomized trial, nineteen participants with diagnosed schizophrenia and CUD were randomly assigned to groups given either active rTMS treatment or a sham rTMS treatment session five times a week for four weeks. The active rTMS treatments targeted the dorsolateral prefrontal cortex (DLPFC) region of the brain, which is associated with the brain’s reward system and executive function.
The researchers found that the group given active rTMS treatment had greater reductions in self-reported cannabis use compared to the sham group, suggesting a clinically relevant effect of rTMS. The active group also trended towards greater reductions in cravings and total symptom scores compared to the sham group.
“People with schizophrenia have very high rates of cannabis use disorder compared to the general population, and there is strong evidence that cannabis use worsens psychiatric symptoms and quality of life in these people,” senior author CAMH clinician scientist Dr Tony George said in a press release.
“Despite the known harmful effects, there is currently no approved treatment for CUD with or without schizophrenia. These results indicate rTMS may be a safe and effective way to reduce cannabis among people with schizophrenia.”
Studying CUD in at-risk populations
While this study is significant in that it is the first to examine rTMS in treating CUD in people with schizophrenia, the researchers noted several limitations of this work. Firstly, the sample size is relatively small, so while these data show promising preliminary results, larger trials are needed to confirm these observations. Specifically, the researchers recommend that larger trials with more female participants would help to enhance the generalizability of these findings.
“It was a difficult study to recruit for given the intensity of time commitment required by patients,” added lead author Dr Karolina Kozak Bidzinski. “However, the awareness patients had of the negative effects cannabis was having on their lives, the expected benefits of reducing their use and noticing the various positive outcomes that would surface throughout the duration of the trial, enabled such a high number of patients to complete the study. Hopefully this work paves the way for more research into investigating the effects of rTMS as a treatment for cannabis use disorder in people with schizophrenia.”
CAMH is Canada’s largest mental health and addiction teaching hospital and produces a wealth of world-leading research in the field. Dr George believes that CAMH is uniquely positioned to enable the kind of research that will serve populations that are often excluded from traditional addiction studies.
“In addition to our ability to conduct clinical trials with brain stimulation at the Temerty Centre, CAMH also has one of the largest schizophrenia outpatient clinics in North America as well as state-of-the-art addiction treatment programs,” said Dr George. “All those factors make CAMH one of the few places in the world that can lead a study like this.”
The dangers of problematic cannabis use
Approximately 22 million people worldwide are thought to be living with CUD, a condition that is typified by experiencing severe cravings and withdrawal symptoms when a person stops using cannabis regularly. As they go through a period of cannabis withdrawal, people with CUD may also experience reduced appetite and body weight, sleeping problems, and emotional disturbances, such as irritability, anger, depression, and anxiety.
Generally, the condition has been associated predominantly with heavy users of recreational cannabis. However, recent studies have shown that patients using cannabis for medicinal reasons may be just as likely to develop problematic cannabis use behaviors and develop CUD.
CUD is a serious health concern that can have severe negative effects on a person’s physical and psychological well-being. For example, evidence suggests that young people with CUD who also struggle with a mood disorder are at a significantly higher risk for self-harm and death by unintentional overdose.
As the researchers behind the new Schizophrenia study explain, people with schizophrenia are known to have very high rates of CUD compared to the general population and this risk may worsen the person’s existing psychiatric problems. Developing effective treatment methods for people with schizophrenia (and other conditions which have been overlooked by the initial wave of studies into CUD) is a crucial step forward in addressing the effects of problematic cannabis use.