M82. Neurite Orientation Dispersion and Density Imaging (NODDI) of the Prefrontal Cortex in Psychosis

Abstract

Background: Individuals with psychosis exhibit changes in prefrontal cortex (PFC) microstructure, including reduced spine density and shorter total dendritic length. However, in vivo evidence of altered PFC microstructure is lacking. We used neurite orientation dispersion and density imaging (NODDI) to investigate cortical microcircuitry in vivo in individuals with psychosis. Method(s): Multishell diffusion imaging and high resolution anatomical T1-weighted imaging was acquired on 67 individuals with a psychotic disorder and 47 healthy control subjects. Using the NODDI model, neurite orientation dispersion index (ODI), a putative marker of dendritic structure and complexity, was calculated and compared between healthy controls and individuals with psychosis using region-of-interest (ROI) and voxel-wise approaches. Result(s): Multivariate ANOVA of the ROI results revealed a significant interaction between PFC sub-region (medial, lateral, and orbitofrontal) and group (p=.002). Follow-up analyses showed that psychosis patients exhibited reduced ODI in the medial PFC of both the left (p=.003) and right (p=.002) hemispheres. Voxel-wise ANCOVA analysis performed using Biological parametric mapping (BPM) to control for voxel-wise grey matter volume showed significant differences between healthy subjects and psychosis patients in the anterior cingulate and right dorsolateral PFC (voxel-wise results cluster-level corrected p,.001). Conclusion(s): Dendritic complexity in anterior cingulate and dorsolateral PFC is reduced in psychosis. Results are consistent with post-mortem findings of reduced dendritic spine density and shorter total dendritic length in the PFC in psychosis. Further work is required to establish the functional consequences of reduced PFC neurite complexity, and determine the effects of antipsychotic medication of neurite complexity measured in vivo in.