Background: Several studies report that patients with psychosis whoused cannabis have a better cognitive performance than those whodid not (Rabin et al. 2011). In a previous study we found out a higherpremorbid IQ, and a better IQ in psychotic patients who smokedcannabis in their lifetime, and our findings were consistent with theidea that this association is due to a better premorbid functioningrather than to an ameliorative effect of cannabis use on cognitiveperformance (Ferraro et al., 2013). A number of authors havehypothesized that psychotic patients who consume cannabis constitutea differentiated subgroup of patients that have better cognitiveand social skills, necessary to engage in illegal drug consumption,than non-using patients (Compton et al., 2011; Løberg et al., 2014;Arnold et al., 2015). Given that the prevalence, and patterns, ofcannabis use are culturally driven, we wanted to test the hypothesis ofa better premorbid functioning in First Episode Psychosis (FEP)cannabis-using and non-using patients coming from differentEuropean countries (England, Italy, Spain, France, the Netherlands)as part of the EUGEI-STUDY.Methods: 1.745 people (746 cases; 999 controls) completed theassessment for Intellectual Quotient (IQ) (WAIS-brief version) premorbidadjustment (Premorbid Adjustment Scale – PAS) and cannabisuse (CEQ-Revised). We first performed a factor analysis on PAScomponents, by obtaining two main factors: “Premorbid SocialAdjustment” (PSA) and “Premorbid Academic Adjustment” (PAA). Wetherefore performed linear mixed models with IQ, PSA, and PAA asdependent variables and cannabis lifetime (Yes/No), subject status(Cases/Controls), gender and age as independent variables.Results: Across all countries, IQ was higher in those patients whosmoked cannabis in their lifetime compared to those who did not(P = 0.027). This IQ difference was only 3 points and was the same forcases and healthy controls (P = 0.949). Similarly, patients who hadsmoked cannabis in their lifetime showed better PSA scores than nonusers (P = 0.009). The difference in PSA score between cannabis-usersand non-users was significantly greater in cases than controls(P = 0.038). Conversely, across all countries, PAA resulted worst inpatients who smoked cannabis lifetime than patients who did not(Po0.001) and this PAA score difference was the same for cases andcontrols (P = 0.693).Discussion: Our cannabis-using FEP patients have higher IQ, better PSAand lower PAA than non user patients across 5 different Europeancountries. Starting from these preliminary results, we can concludethat a better PSA is significantly associated with cannabis use in FEPpatients. Nevertheless, in an exploratory analysis, a better IQ resultedrelated to a better PAA (o0.001) but not to PSA (P = 0.260); thusindicating an independent relationship of IQ and PSA with cannabisuse. Further analysis are required in order to model these multivariaterelationships.
Original languageEnglish
Number of pages2
Publication statusPublished - 2016

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