A Cannabinoid Receptor 1 Polymorphism Is Protective Against Major Depressive Disorder in Methadone-Maintained Outpatients

Background and Objectives: The burden of opiate dependence not only relies on somatic complications such as infectious diseases or acute intoxication but also on frequent psychiatric events such as major depressive disorder (MDD) and suicidal behavior (SB). Given the preclinical and clinical evidence regarding the associations between cannabinoid systems and both opiate dependence and psychiatric disorders, we chose to address whether one single nucleotide polymorphism (SNP) of the cannabinoid receptor type 1 gene (CNR1) named rs2023239 would be associated with lifetime MDD and SB in a population of opiate-dependent outpatients remitted under stable methadone treatment. Methods: Sociodemographic and clinical data were included as independent factors in two logistic regression models aimed at predicting SB and MDD, respectively, performed with 85 Caucasian individuals. Results: The minor C allele of rs2023239 showed an independent protective effect against lifetime MDD after adjustment for potential confounders. It was not associated with variables related to suicidal behavior. Conclusions and Scientific Significance: Despite limitations due to the modest sample size, our results are consistent with previous research on the endocannabinoid system and suggest new leads for detecting subjects at risk of MDD, which remains insufficiently diagnosed and treated in patients suffering from severe addictive disorders.