Symposium: MMN as a translational biomarker of psychosis: from bench-to-bedside-to-real-world community settings
Thursday, Sep 10, 2015
Structural and functional brain correlates of at-risk mental state
PRC Translational Neuroscience & Mental Health Research, The University of Newcastle, Callaghan, Australia
At-risk mental state (ARMS) is characterized by a significant drop of global function levels (GAF) when occurring together with emerging attenuated or brief limited intermittent psychotic symptoms (BLIPS) or having an immediate family history of schizophrenia, thus predicting a high risk of developing a severe mental illness. Brain imaging research to date has provided some evidence of emerging and progressive grey and white matter abnormalities in the early phase of psychosis. We investigated mismatch negativity (MMN) as well as grey and white matter changes in individuals meeting ARMS criteria in our Mind in Transition (MinT) project. Contrary to some other reports, we did not find differences of MMN amplitudes of 85 ARMS versus 61 healthy individuals or a change of MMN amplitudes in ARMS individuals when followed up after one year with only 7.1% developing some form of psychotic illness. Lower GAF ratings scores correlated with reduced grey matter thickness in frontal, prefrontal, and occipital cortical areas whereas symptom rating scores correlated with reduced grey matter thickness in left and right superior frontal gyri, right anterior cingulate, and right medial occipito-temporal cortex (i.e. lingual gyrus). On other morphological measures, ARMS individuals with low versus high symptom expression (medial split) did not differ in total brain volume, grey or white matter volume, or pial or white matter surface areas. These findings suggest that low-grade psychotic symptoms and functional impairment are associated with reduced cortical grey matter thickness, a putative measure of brain pathology.