Early onset first episode psychosis: dimensional structure of symptoms, clinical subtypes and related neurodevelopmental markers.

Despite the growing interest in a dimensional approach to the assessment of symptoms and clinically relevant phenomena in schizophrenia spectrum disorders, very few studies, to date, have examined the dimensional structure of symptoms in early onset first episode psychosis. In the present study, we assessed a sample of 60 children and adolescents of both sexes with first episode schizophrenia spectrum psychosis. A principal component analysis (PCA) of the Positive and Negative Syndrome Scale (PANSS) was performed and the factors obtained were used to carry out a cluster analysis. Sex, age of onset before or after 13, markers of early neurodevelopmental impairment and intellectual disabilities were considered as variables to characterized potential clinical subtypes, applying a one-way analysis of variance. Four factors were extracted ("negative symptoms", "delusions", "conceptual disorganization" and "paranoid/hostility"), each of them identifying a discrete clinical subtype of patients. No difference was found among the groups about sex and age of onset; delayed speech/language development was significantly associated with the "delusions" subtype and both "conceptual disorganization" and "delusions" subtypes showed a lower intelligence quotient (IQ). The four factors model we presented highlights "negative symptoms" as the most consistent factor; among positive symptoms, unusual thought content and conceptual disorganization resulted more distinctive of psychosis, at this age range, than perceptual abnormalities. Evolutionary trajectories of the four clinical subtypes we obtained seem to be influenced by cognitive and neurodevelopmental impairment rather than sex and age of onset.