Link Between Weight Gain and Antipsychotic Treatment

Cannabinoids may be concerned in the excess weight that happens in individuals with schizophrenia who are treated with the antipsychotic olanzapine, with respect to a pilot research reported in the Journal of Clinical Psychopharmacology by investigators at the Institut universitaire en santé mentale de Montréal (IUSMM) and Université de Montréal (UdeM).

First author Stéphane Potvin stated “Cannabis provides psychoactive effects through endogenous cannabinoids, which are a kind of chemicals identified in the brain,”. Our initial data recommend that endogenous cannabinoids may be involved in excess weight in individuals with schizophrenia via action on particular parts of the brain engaged in appetite.

The research team recently examined the eating behaviour of 15 individuals with schizophrenia who were treated for 16 weeks with olanzapine, an antipsychotic well-known to stimulate appetite. These individuals viewed neutral images or images developed to stimulate their appetites while in a functional magnetic resonance imaging (fMRI) scan, before and following 16 weeks of therapy with olanzapine. The team also assessed the subjects’ fasting glucose, insulin and lipid concentration along with their levels of endogenous cannabinoids.


After the therapy, the investigators noticed hyperactivation in the left amygdala (limbic region) in schizophrenia sufferers, comparative to a control group of healthy people. These brain modifications were connected with enhanced levels of glucose, triglycerides and anandamide, which is the major cannabinoid neurotransmitter. While in the therapy, the individuals also gained weight and had less positive symptoms (delusions and hallucinations). The statistical evaluation indicates the involvement of anandamide in amygdala hyperactivation in people who viewed images that stimulate appetite.

“This outcome is reliable with reports in the scientific literature that an raise in cannabinoids, especially anandamide, is engaged in the motivational factor of eating behaviour. It is also constant with the reality that cannabis smoking raises appetite, a well-identified phenomenon that many individuals call the ‘munchies,'” described Stéphane Potvin. “To our understanding, this is the initial neuroimaging research that reports a connection between anandamide levels and disordered eating in individuals with schizophrenia, although a cause-and-effect connection has not been confirmed. These preliminary outcomes must be proved with larger sample sizes. Further research will allow us to much better understand the weight gain related with antipsychotic treatment for schizophrenia, which continues to be a major clinical issue, as some antipsychotics lead to major metabolic side effects,” concluded the researcher.