Most of the studies examining the impact of cannabis use in first episode psychosis (FEP) have been carried out in samples with adult-onset FEP. Data in persons with early onset psychosis (EOP) is scarce. The aims of the study were: To describe the prevalence of lifetime cannabis use, current use, and daily use in patients with EOP compared to healthy controls. To study the differences in clinical presentation between cannabis users and non-users. To examine the risk of presenting an EOP associated with cannabis use and the effect of doses and age of onset of use. An observational cross-sectional study was performed in 90 EOP cases and 62 healthy controls, aged between 7 and 17 years. Our results show a higher prevalence of lifetime use (p = 0002), current use (p < 0.001), and daily use (p < 0.001) in EOP cases in comparison with healthy controls. Regarding clinical presentation, we did not find significant differences in any subscale of the Positive and Negative Syndrome Scale (PANSS). Non-user patients presented more severe depressive symptoms (p = 0002) and worse social functioning than cannabis users (p = 0026). Compared with subjects who never used cannabis, the risk of an EOP was significantly higher for those with a lifetime use (OR = 2.88, p = 0.002)current use (O.R = 6.09, p < 0001), and especially in those with daily use (O.R = 42.77, p = <0001). We found a higher risk of EOP in patients that have used cannabis before 15 years of age. In conclusion, it is necessary to develop early- detection and specific treatment programs for adolescents with cannabis use.
Keywords: Adolescence; Cannabis daily use; Cannabis use; Early onset psychosis.
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