Schizophrenia is a chronic, severe, and debilitating brain disorder that affects about 1% of the population. Delusions, hallucinations, movement disorders and disorganized thinking are considered positive symptoms. Negative symptoms include flat affect, social withdrawal and lack of pleasure in everyday life. Cognitive symptoms are poor attention, poor executive functioning and decision-making, and poor memory.
Hyperactivity of dopamine and serotonin, two important neurotransmitters, plays a critical role in the cause of schizophrenia. However, other neurotransmitters and their receptors are involved as well.1 Cannabinoid receptors exist in high numbers in the area of the brain implicated in schizophrenia,2 with accumulating evidence that endocannabinoid system dysfunction is likely to play a role in this condition.3 Remember that if the endocannabinoid system is not functioning properly, the brain cannot balance the hyperactivity of the involved neurotransmitters, which results in an imbalance in the messages that brain cells are sending to each other. There are also numerous studies that report that schizophrenia is likely an inflammatory illness.4,5,6,7
The mainstay of treatment for patients with schizophrenia is antipsychotic medications. These drugs have been shown to be effective in reducing the positive symptoms of schizophrenia but do not appear to help with the negative symptoms or the cognitive symptoms. Additionally, antipsychotic medications have numerous side effects that can become intolerable, causing patients to discontinue use. Approximately one third of patients are treatment-resistant, meaning they have not responded to two or more medications.
Recent research reveals that CBD is antipsychotic and that THC may be (but not always) pro-psychotic.
There is some evidence that prolonged use of high potency THC use in teenagers with a genetic predisposition for psychiatric disease may increase the risk of schizophrenia.11 A very recent study found that young cannabis users aged 16-23 years who had a variation in their AKT1 gene were more likely to have an acute psychotic response to cannabis.12
I have a small number of patients with schizophrenia in my practice who are using THC-rich cannabis with good results, but they are selective in choosing cannabis that is sedating and calming. Helpful terpenoids are myrcene, limonene and linalool. Others are using CBD-rich cannabis with reports that they experienced fewer hallucinations and delusions, had improved mood and much less anxiety. I have a number of patients who are using both cannabis and antipsychotic medications, finding that cannabis minimizes the side effects of the pharmaceuticals while treating breakthrough anxiety and insomnia. A few patients are managing symptoms with cannabis treatment alone.
Werner, Felix-Martin, and Rafael Coveñas. “Classical Neurotransmitters and Neuropeptides Involved in Schizophrenia: How to Choose the Appropriate Antipsychotic Drug?.” Current Drug Therapy 8.2 (2013): 132-143.
Glass, M., R. L. M. Faull, and M. Dragunow. “Cannabinoid receptors in the human brain: a detailed anatomical and quantitative autoradiographic study in the fetal, neonatal and adult human brain.” Neuroscience 77.2 (1997): 299-318.
Leweke, F. M., et al. “Elevated endogenous cannabinoids in schizophrenia.” Neuroreport 10.8 (1999): 1665-1669.
Hanson, Daniel R., and Irving I. Gottesman. “Theories of schizophrenia: a genetic-inflammatory-vascular synthesis.” BMC Medical Genetics 6.1 (2005): 7.
Coelho, Fernanda Matos, et al. “Increased serum levels of inflammatory markers in chronic institutionalized patients with schizophrenia.” Neuroimmunomodulation 15.2 (2008): 140-144.
Drexhage, Roosmarijn C., et al. “The mononuclear phagocyte system and its cytokine inflammatory networks in schizophrenia and bipolar disorder.” (2010): 59-76.
Sommer, Iris E., et al. “Nonsteroidal anti-inflammatory drugs in schizophrenia: ready for practice or a good start? A meta-analysis.” The Journal of clinical psychiatry 73.4 (2012): 414-419.
Leweke, F. M., et al. “Cannabidiol as an antipsychotic: a double-blind, controlled clinical trial on cannabidiol vs amisulpride in acute schizophrenics.” 2005 Symposium on the Cannabinoids, Burlington, Vermont, International Cannabinoid Research Society.
Morgan, Celia JA, and H. Valerie Curran. “Effects of cannabidiol on schizophrenia-like symptoms in people who use cannabis.” The British Journal of Psychiatry 192.4 (2008): 306-307.
Leweke, F. M., et al. “Cannabidiol enhances anandamide signaling and alleviates psychotic symptoms of schizophrenia.” Translational psychiatry 2.3 (2012): e94.
Di Forti, Marta, et al. “High-potency cannabis and the risk of psychosis.” The British Journal of Psychiatry 195.6 (2009): 488-491.
Morgan, C. J. A., et al. “AKT1 genotype moderates the acute psychotomimetic effects of naturalistically smoked cannabis in young cannabis smokers.” Translational Psychiatry 6.2 (2016): e738.