IntroductionPoor insight is a distinctive feature of the psychotic spectrum disorders. One of the theories of the etiology of awareness is the neuropsychological view which suggests that there is an association of awareness, cognition and brain changes in psychosis. But the relationship of cognitive reserve, insight and drug use is still an unexplored field in the psychosis literature.The aim of this research is to analyze the possible moderator effect of cannabis use in the relation between cognitive reserve and insight in psychosis.MethodA longitudinal study was held with 65 patients with FEP from 3 main hospitals in the Basque Country (Spain). All patients underwent clinical and functional evaluations at base line and longitudinally at one year follow up. Insight was measured using the insight and judgement item (G12) from the Positive and Negative Syndrome Scale (PANSS). The cognitive reserve was measured using the Vocabulary sub-scale from WAIS-III and educational level. Drug use was assessed during the clinical interview.ResultsOne year follow-up data were available for 35 patients. Significant relation between the cognitive reserve and G12 item (β = −9.58; p < .05) was found as long as the cannabis use is included as a moderator (β = −9.34; p < .05).ConclusionAs it is a complex multidimensional concept, a more complete explanatory model of the insight recognizing the functions of the cognitive reserve and others covariates as drug use, defines the role of each variable of the illness and facilitates the objects of treatment definitions.FundingBasque Government(2008111010), EITB-Maratoia(BIO 09/EM/015).