Cannabis use is considered an established risk factor for psychosis development. Differentiating between cannabis-induced disorders and schizophrenia is useful for prognostic and therapeutic purposes. Three inpatients groups were differentiated: cannabis-induced psychosis (CIP) (n = 69; mean age = 27.4, SD = 6.5; 82.6% males), schizophrenia with cannabis abuse or dependence (SZ + CB) (n = 57; mean age = 31.9, SD = 10.1; 94.7% males) and schizophrenia without cannabis abuse or dependence (SZ) (n = 181; mean age = 41.8, SD = 13.3; 54.1% males). The Psychiatric Research Interview for Substance and Mental Disorders (PRISM-IV) scale was used to differentiate induced psychosis. The CIP group presented lower mean scores on the negative PANSS subscale (M = 12.9, SD = 5.9; F = 32.24, p < 0.001), fewer auditory hallucinations (60.3%; X² = 6.60, p = 0.037) and greater presence of mania (26.1% vs. 12.3%; X² = 32.58, p < 0.001) than the SZ + CB group. There were few clinical differences between patients with schizophrenia, regardless of previous cannabis use. The age of first admission due to psychosis was lower in both psychotic inpatients groups with cannabis use (M = 26.1, SD = 6.4 in CIP and M = 25.3, SD = 6.2 in SZ + CB; X² = 20.02, p < 0,001). A clinical pattern characteristic of cannabis-induced psychosis was not observed, but the precipitating role of cannabis in the appearance of psychotic symptoms was demonstrated, given the lower age of first admission due to psychosis in cannabis user groups.
El consumo de cannabis se considera un factor de riesgo establecido para el desarrollo de psicosis. Diferenciar los trastornos inducidos por cannabis de la esquizofrenia resulta útil desde el punto de vista pronóstico y terapéutico. Se diferenciaron tres grupos de pacientes hospitalizados: psicosis inducida por cannabis (PIC) (n = 69; Media de edad = 27,4, DE = 6,5; 82,6 % varones), esquizofrenia con abuso o dependencia de cannabis (EZ + CB) (n = 57; Media de edad = 31,9, DE = 10,1; 94,7% varones) y esquizofrenia sin abuso o dependencia de cannabis (EZ) (n = 181; Media de edad = 41,8, DE = 13,3; 54,1% varones). Se utilizó la escala Psychiatric Research Interview for Substance and Mental Disorders (PRISM-IV) para la diferenciación de cuadros inducidos. El grupo PIC presentó puntaciones inferiores en la subescala PANSS negativa (M = 12,9, DE = 5,9; F = 32,24; p < 0,001), menos alucinaciones auditivas (60,3%; X² = 6,60; p = 0,037) y mayor presencia de manía (26,1% vs. 12,3%; X² = 32,58; p < 0,001) en comparación con el grupo EZ + CB. Hubo pocas diferencias clínicas entre los pacientes con esquizofrenia, independientemente del consumo de cannabis. La edad del primer ingreso por psicosis fue menor en ambos grupos de psicóticos consumidores (M = 26,1, DE = 6,4 en PIC y M = 25,3, DE = 6,2 en EZ + CB; X² = 20,02; p < 0,001). No se observó un patrón clínico característico de las psicosis inducidas por cannabis, aunque sí se demostró el papel precipitante del cannabis en la aparición de psicosis, dada la menor edad de ingreso en los consumidores.