Cortical thickness has been widely studied in individuals with schizophrenia and, in particular, first-episode psychosis. Abnormalities have been described, although there is, to date, a lack of consensus regarding changes across time and correlations with clinical and functional outcomes of the illness. One hundred and twenty-three first-episode psychosis patients and 74 healthy volunteers were subjected to magnetic resonance imaging scans and clinical and functional assessments by different scales at four consecutive visits during a 10 year follow-up period. Linear mixed effects models were applied to our data to compute cortical thickness changes over time in (1) schizophrenia patients versus healthy controls and (2) in patients with good versus poor functional outcome. The associations between cortical thickness percentage changes and clinical and functional status at 10 years were also assessed. The patients presented a thinner cortex than the controls at baseline (b's = -0.06; q ≤ 0.00023) with non-significant coefficients for the interaction term (follow-up time x group) (b's = -0.001; q ≥ 0.681). Poor functioning patients presented statistically significant coefficients for the interaction term (follow-up time x functionality) (left: b = -0.005, q = 0.019; right: b = -0.005, q = 0.022). In contrast, no correlations were found between cortical thickness measurements and clinical variables at 10 years. Overall, there were widespread thickness anomalies in first-episode psychosis patients across cortical regions that remained stable across time. Progressive thickness changes were related to patient functional outcomes, with progressive and steeper cortical thinning in patients with worse functional outcomes and a stabilization in those with better outcomes.
Keywords: Cortical thickness; First-episode psychosis; Outcome; Schizophrenia spectrum disorders; Stratification.
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