Cannabis use is associated with increased CCL11 plasma levels in young healthy volunteers

Cannabis is a widely used recreational drug. Its effect on human health and psychosis remains controversial. In this study, we aimed to explore the possibility that cannabis use influenced CCL11 plasma levels. Increased CCL11 chemokine has been reported in schizophrenia and cannabis is a known trigger of schizophrenia. Additionally, plasma levels of the chemokine CCL11 have recently been shown to increase with age and with cognitive deficits and hippocampal neurogenesis. For this study, a total of 87 healthy volunteers (68% men, age range 18-35 years) completed the Cannabis Experience Questionnaire that included information on sociodemographic and morphometric data and provided a blood sample for CCL11 measurement. 'Current users' of cannabis (n=18) had significantly higher CCL11 plasma levels compared to 'past users' (n=33) and 'never users' (n=36) [F(3,84)=3.649; p=0.030]. The latter two groups had similar CCL11 levels. Higher CCL11 plasma levels could not be attributed to gender, age, body mass index, physical activity or use of other legal/illegal drugs. These results suggest that cannabis use increases CCL11 plasma levels and the effects are reversible when cannabis use ceases.