Dimensional structure of first episode psychosis

Aim: Current diagnostic systems, DSM-5 and ICD-10, still adopt a categorical approach to classify psychotic disorders. The present study was aimed at investigating the structure of psychotic symptomatology in both affective and non-affective psychosis from a dimensional approach. Methods: Participants with a first episode psychosis (FEP) were recruited from a cluster-randomized controlled trial (GET-UP PIANO TRIAL), offered to all Community Mental Health Centres (CMHCs) located across two northern Italian regions. After clinical stabilization, patients were assessed with a comprehensive set of psychopathological measures including the Positive and Negative Syndrome Scale, the Hamilton Depression Rating Scale and the Bech-Rafaelsen Mania Rating Scale. A two-step cluster analysis was performed. Results: Overall, 257 FEP patients (male, n = 171, 66.5%; mean age = 24.96 ± 4.56) were included in the study. The cluster analysis revealed a robust four-cluster solution: delusional-persecutory (n = 82; 31.9%), depressed (n = 95; 37%), excited (n = 26; 10.1%) and negative-disorganized (n = 54; 21%), thus suggesting a quadripartite structure with both affective and non-affective dimensions. Among non-affective dimensions, negative and disorganization symptoms constituted a unique construct apart from positive symptoms. Conclusions: Symptom dimensions may represent a useful tool for dissecting the indistinct and non-specific psychopathology of FEP in order to better target specific interventions.