The role of premorbid iq and age of onset as useful predictors of clinical, functional outcomes, and recovery of individuals with a first episode of psychosis

Abstract

Background: premorbid IQ (pIQ) and age of onset are predictors of clinical severity and long‐term functioning after a first episode of psychosis. However, the additive influence of these variables on clinical, functional, and recovery rates outcomes is largely unknown. Methods: we characterized 255 individuals who have experienced a first episode of psychosis in four a priori defined subgroups based on pIQ (low pIQ < 85; average pIQ ≥ 85) and age of onset (early onset < 18 years; adult onset ≥ 18 years). We conducted clinical and functional assessments at baseline and at two‐year follow‐up. We calculated symptom remission and recovery rates using the Positive and Negative Symptoms of Schizophrenia Schedule (PANSS) and the Global Assessment Functioning (GAF or Children‐GAF). We examined clinical and functional changes with pair‐wise comparisons and two‐way mixed ANOVA. We built hierarchical lineal and logistic regression models to estimate the predictive value of the independent variables over functioning or recovery rates. Results: early-onset patients had more severe positive symptoms and poorer functioning than adult‐onset pa-tients. At two‐year follow‐up, only early‐onset with low pIQ and adult‐onset with average pIQ subgroups differed consistently, with the former having more negative symptoms (d = 0.59), poorer functioning (d = 0.82), lower remission (61% vs. 81.1%), and clinical recovery (34.1% vs. 62.2%). Con-clusions: early‐onset individuals with low pIQ may present persistent negative symptoms, lower functioning, and less recovery likelihood at two‐year follow‐up. Intensive cognitive and functional programs for these individuals merit testing to improve long‐term recovery rates in this subgroup.