Poster #103 INTERACTION BETWEEN COMT GENOTYPE, CANNABIS USE, AND BFQ MEASURES OF SOCIABILITY

Background: Cannabis use is associated with greater risk for psychosis in individuals vulnerable for developing schizophrenia-spectrum disorders [1]. Accumulating evidence indicates that cannabis use may be associated with poor social involvement, suspiciousness, hostility, lack of efficiency and poor organization, emotional reactivity, vulnerability to stress, all associated with an increased risk of psychosis [2]. In particular poor premorbid social adjustment is one manifestation of vulnerability to adult psychotic disorders [3]. Catechol-O-methyltransferase (COMT) is an important enzyme in the metabolism of dopamine and disturbance in dopamine function is proposed to be central to the pathogenesis of schizophrenia. A functional variant in the COMT gene, the Val158Met (“val/met”) polymorphism, has been associated in prior studies with several phenotypes of human personality related to psychosis [4]. In this study we examined the relationship between the COMT Val158Met (“val/met”) polymorphism, cannabis use and sociability in a healthy adult sample. We hypothesized that cannabis users and individuals with the low-activity genotype would be less sociable and that this effect would be more pronounced in met/met cannabis users than in cannabis-naïve controls. Methods: 216 healthy subjects, genotyped for rs 4680 (“val/met”), were evaluated using the Drug Abuse Screening Test (DAST), a brief instrument for clinical screening of cannabis use, and completed a measure of normal personality, the Big Five Personality Questionnaire (BFQ). Results: At the BFQ, users scored lower than controls on agreeableness (p=0.07), kindness/friendly attitude (p=0.05), conscientiousness (p=0.003) and scrupulosity (p=0.006). Results revealed that individuals homozygous for the COMT low activity allele had lower agreeableness (p=0.03) on BFQ. Met/met cannabis users expressed lower levels in extraversion (p=0.02), dinamism (p=0.04) and demonstrated a trend toward lower agreeableness (p=0.06) on BFQ. These effects were not present in the other genotype groups. Discussion: These results suggest an interaction between the Val158Met (’val/met’) polymorphism and cannabis use on sociability. Evaluation of cannabis use may help to explain the involvement of the COMT locus in susceptibility to psychosis-related personality traits.