Cannabis Use Lowered a Key Endocannabinoid in People with Schizophrenia

In a study of 93 individuals (29 treatment-resistant schizophrenia on clozapine, 31 on other antipsychotics, 33 controls), those reporting lifetime cannabis use had significantly lower plasma 2-AG levels (p=0.011), and this remained the only significant factor in models controlling for confounders. Patients on non-clozapine antipsychotics showed altered CB2 receptor levels compared to controls (p=0.022). AEA levels and CB2 levels did not differ between patients and controls overall.

Cross-sectional study measuring blood levels of AEA, 2-AG, and CB2 receptor in 93 participants divided into three groups: clozapine-treated schizophrenia (treatment-resistant), other antipsychotic-treated schizophrenia, and healthy controls. Generalized linear models controlled for confounders.

This provides the first evidence that cannabis use and antipsychotic medication type independently modulate different components of the peripheral endocannabinoid system in schizophrenia. The distinction between clozapine and other antipsychotics on CB2 levels suggests ECS interactions may partly explain different treatment responses.

Understanding how cannabis use modifies the endocannabinoid system in schizophrenia could inform both treatment selection and risk assessment for patients who use cannabis alongside antipsychotic medication.

Small sample size. Cross-sectional design cannot establish causation. Peripheral blood measurements may not reflect brain endocannabinoid activity. Lifetime cannabis use is a crude measure that does not capture recency, frequency, or type.