Appreciating symptoms and deficits in schizophrenia: right posterior insula and poor insight

Poor insight is one of the most prominent clinical features of psychosis. Loss of insight in schizophrenia is characterised by abnormalities in awareness and attribution of the origin of pathological mental phenomena. Converging lines of investigations suggest that in healthy individuals, right posterior insula plays an important role in awareness and self-attribution of mental phenomena, contributing to the emergence of a sense of self (Craig, 2002; Farrer et al., 2003). In addition, neuroimaging studies investigating brain morphometry in schizophrenia have consistently reported deficits in the structure of insula (Glahn et al., 2008; Ellison-Wright and Bullmore, 2010). In the present study, we investigated the relationship between the morphometry of posterior insula and degree of insight in a sample of 57 patients in a stable phase of illness using high resolution Magnetic Resonance Imaging. We measured the cortical surface area and local white matter volume of posterior insula. A significant inverse relationship was found between right posterior insular structure and degree of insight in schizophrenia. No such relationship was noted for left posterior insula. Our results highlight the importance of a predominantly right-sided network that includes posterior insula as the neural basis of insight. Abnormalities in interoceptive awareness and self-appraisal of emotional states may contribute to the loss of insight seen in schizophrenia.