T155. PROGRESSION OF NEUROANATOMICAL ABNORMALITIES AFTER FIRST-EPISODE OF PSYCHOSIS: A 3-YEAR LONGITUDINAL STRUCTURAL MRI STUDY

BACKGROUND: The extent and location of longitudinal morphometric changes after first-episode of psychosis (FEP) remains unclear. We investigated the progressive profile of ventricular and cortico-subcortical regions over a 3-year period in FEP patients compared with healthy controls (HC), and whether any progressive neuroanatomical changes were related to clinical factors. METHODS: High resolution 1.5T T1-weighted MR images were obtained from 28 FEP patients and 28 HCs shortly after presentation to services and again after 3-year follow-up. The longitudinal FreeSurfer pipeline (v.5.3.0) was used for regional volumetric and cortical reconstruction image analyses. Repeated-measures ANCOVA and vertex-wise linear regression analyses were used to compare progressive changes in relation to subcortical structures/ventricles and thickness across the cortical mantle, respectively, between groups. Partial correlations were used to determine associations of progressive neuroanatomical change with clinical and functional characteristics. RESULTS: Compared with controls, patients displayed progressively reduced volume of the caudate [F(1,51)=5.86, p=0.02, Hedges’ g=0.66], putamen [F(1,51)=6.06, p=0.02, g=0.67] and thalamus [F(1,51)=6.99, p=0.01, g=0.72], with a trend for increased lateral ventricular volume [F(1,51)=3.37, p=0.07, g=0.50] more prominent on the right [F(1, 51)=4.03, p=0.05], and significantly increased rate of cortical thinning [F(1,52)=5.11, p=0.028)] at a mean difference of 0.844% [95% CI (0.095, 1.593)] in the left lateral orbitofrontal region (LLOFR) over the 3-year period. In FEP individuals, greater reduction in putamen volume over time was associated with low cumulative antipsychotic medication dose (r=0.49, p=0.01), and increasing lateral ventricular volume over time was associated with worsening negative symptoms (r=0.41, p=0.04) and poorer global assessment of functioning (r=-0.41, p=0.04). DISCUSSION: Our results demonstrate existence of localised progressive structural disturbance in the subnetwork of the cortico-striato-thalamo-cortical circuitry after the onset of psychosis. Furthermore, increasing ventricular volume is a neuroanatomical marker of poorer clinical and functional outcome. These findings lend weight to the evidence of early progressive brain changes in psychotic disorders and thus, this knowledge could potentially contribute to the identification of imaging biomarkers for timely intervention.