Symptom Attribution in first episode psychosis: A cortical thickness study

One dimension of insight in psychosis is the ability to attribute correctly one's symptoms to a mental disorder. Recent work suggests that gray matter volumes of the orbitofrontal cortex (OFC) are correlated with aggregate symptom attribution scores in first-episode schizophrenia. Whether regions beyond the OFC are important for symptom attribution remains to be established. Further, whether common or separable neural systems underlie attribution of specific symptoms (e.g., delusions, asociality) has not been studied. In the current magnetic resonance imaging study, 52 people with a first-episode psychosis (FEP) were rated with the Scale for Assessment of Unawareness of Mental Disorder on attribution of hallucinations, delusions, flat affect and asociality. Attribution ratings were regressed on cortical thickness at 81,924 vertices. Mapping statistics revealed that delusion misattribution was associated with thickness in the OFC [Brodmann's area (BA) 11/47]. Delusion, flat affect and asociality misattribution were associated with cortical thinness in the dorsolateral prefrontal cortex (BA 9/46). Differential associations emerged between each attribution item and cortical thickness/thinness in a variety of frontal, temporal, parietal and occipital areas. The results imply a selective role for the OFC in delusion misattribution in FEP. Evidence for cortical thickness covariation in a variety of regions suggests partial independence in the neural architecture underlying attribution for different symptoms in FEP.