Symptom attribution and frontal cortical thickness in first-episode schizophrenia

Misattribution of symptoms is a common feature of schizophrenia, and likely involves impairment of metacognitive function that may be mediated by the frontal cortex. We aimed to compare frontal cortical thickness in first-episode schizophrenia (FES) patients with matched controls, and investigate its relationship with the symptom attribution dimension of insight in FES patients.

We examined frontal cortical thickness in 92 minimally treated FES patients at baseline presentation and 93 healthy controls aged 16-45 years. We examined for correlations between symptom attribution as determined by the Birchwood Insight Scale (BIS) symptom relabeling subscale score and cortical thickness of frontal regions of interest (ROIs). We then examined for an association between symptom attribution and cortical thickness using multiple regression analysis.

FES patients exhibited significantly reduced cortical thicknesses for a number of frontal regions, namely the left medial orbitofrontal, left superior frontal, left frontal pole, right rostral middle frontal, right lateral orbitofrontal and right superior frontal regions. Reduced cortical thickness in FES patients was associated with symptom misattribution for the left and right rostral middle frontal, left caudal anterior cingulate, right superior frontal, and left and right pars triangularis regions. Reduced left rostral middle frontal thickness and left anterior cingulate thickness remained significant on regression analysis.

Our findings suggest that frontal neuroanatomical deficits that are present early in the disease process may be critical to the pathogenesis of symptom attribution in schizophrenia.