Cannabis use and genes of endocannabinoid system: their role in psychotic symptoms and cognition in first-episode psychosis.

Objectives. To evaluate the association of cannabis use, genes of the endocannabinoid system and their interaction on clinical symptoms and cognitive performance in patients with a first-episode of pyschosis. Background. The role of both cannabis use and individual genetic background has been shown in the risk for psychosis. However, the influence of cannabis and variability at endocannabinoid genes on the psychosis outcome still remains inconclusive. Materials and Methods. The sample comprised 43 Caucasian individuals with a first-episode of psychosis (mean age(sd)=25.80(6.39) years, 76.7% males, 51.2% cannabis users).There were no differences in age and sex between cannabis users and non-users. Genetic variability was assessed by genotyping one Single Nucleotide Polymorphism (SNP) in each gene (CNR1-rs1049353 and CNR2-rs2501431). Clinical (PANSS, GAF) and neuropsychological (WAIS, WMS, BADS) scales were administered. Results and conclusions. Genotypic frequencies did not differ between cannabis users and non-users. Cannabis use was associated with better manipulative abilities (IQ-M-WAIS, p=0.029) and better executive function (BADS, p=0.036). CNR1-T allele carriers presented higher disorganized and negative syndrome scores (p=0.001 and p=0.044, respectively). The interaction models evidenced a combined effect of CNR1 and cannabis use on the negative syndrome-PANSS (p=0.037). These results suggest the role of cannabis use and genetic background on cognitive and psychopathological outcomes in first-episode psychosis. However, evidence is still scant, and further investigation in larger samples is needed.