AbstractsPsychology

Research Doctorate - Doctor of Philosophy (PhD) The reliable identification of the schizophrenia prodrome is a prerequisite for early intervention in young people considered “at-risk” of developing this severe mental illness. Clinical at-risk criteria, however, still lack predictive specificity to reliably predict outcome. Brain imaging research has added substantial evidence to the notion of emerging and progressive grey and white matter abnormalities in the early phase of illness. The purpose of this study was to investigate structural brain changes associated with the clinical profile of the At-Risk Mental State (ARMS) syndrome, along with cognitive and psychophysiological measures that have been linked schizophrenia. Forty-two young individuals meeting ARMS criteria of the Comprehensive Assessment of At-risk Mental State (CAARMS) were included in the study. Surface-based methods were applied to quantify measures of cortical structure in high-resolution MRI scans. Participants underwent clinical and cognitive assessments. Event-related potentials (i.e. Mismatch Negativity and P3a) were recorded whilst study participants performed an auditory oddball task. A median-split of dividing the study participants into two groups with low versus high symptom expression (ARMS-LS vs. ARMS-HS) based on CAARMS symptom ratings revealed significantly reduced mean cortical grey matter thickness in the more symptomatic group. There was no significant group difference in total brain volume, grey or white matter volume, or pial or white matter surface areas. ARMS-HS presented significantly impaired in socio-occupational and social/role functioning, as well as performed lower in verbal fluency when compared to ARMS-LS. Vertex-wise correlation analyses confirmed significant associations (p< .05 corrected) of CAAMRS symptom rating scores 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). Reduced grey matter in frontal, prefrontal, and occipital cortical areas were associated with low function ratings. Verbal Fluency task performance largely overlapped with the frontal brain areas identified for low function ratings by reduced regional grey matter thickness correlation maps. These findings suggest that emerging psychopathology as defined by CAARMS for ARMS (i.e. low-grade psychotic symptom expression and functional impairment) is associated with reduced cortical grey matter thickness, a putative measure of brain pathology. Future research should investigate whether regional cortical grey matter reduction is associated with a higher risk of developing schizophrenia.