Prodromal symptoms and remission following first episode psychosis

Describing the trajectory of prodromal symptoms has obvious appeal in supporting advances towards sub-clinical intervention. Identifying clinical phenomena associated with unfavourable illness outcomes could have greater significance in explaining some heterogeneity within and between psychotic disorders and advancing understanding of pre-psychotic typologies. Few studies have assessed the continuity, if any, between prodromal phases and illness outcome one year after treatment.

We assessed 375 people with first-episode psychosis (FEP) and 215 (57.4%) were seen approximately one year later. We performed factor analysis on prodromal symptom items obtained by interview with families and participants and identified a five-factor solution. We determined whether these factors predicted non-remission from psychosis in the presence of other factors that may predict outcome including premorbid adjustment, duration of prodrome and untreated psychosis (DUP), baseline symptoms and DSM-IV diagnoses. We used random forest classification to predict the most important variables and logistic regression to identify specific predictors.

We identified five prodromal symptom factors comprising Negative Symptoms, General Psychopathology, Reality Distortion, Strange Ideas and Irritability. Prodromal symptoms did not predict a greater risk of non-remission with the exception of Irritability and this factor was also associated with earlier age at onset, being male and a diagnosis of substance-induced psychosis. Being male, DUP and baseline positive symptoms predicted non-remission at one year.

Prodromal symptoms were not linked with outcome after a year of treatment which could be explained by greater heterogeneity in illness psychopathology which may be more pronounced in broad FEP diagnoses at different stages. It could also be explained by prodromal symptoms exerting greater influence earlier in the course illness.