Investigation of Microstructural Changes in Thalamus Nuclei in Schizophrenia using Diffusion Weighted Imaging

Abstract

Disruption in the thalamus, such as volume and thalamo-cortical connectivity change, is regarded as a core psychopathology in schizophrenia. However, whether the nucleus specific thalamic microstructure changes exist in the early stage of the disorder is still unknown. To determine this gap in knowledge, the microstructural complexity of sub-thalamic ROIs with specific connection to the cortex in patients with first episode psychosis (FEP) was compared to that of healthy controls with diffusion kurtosis imaging (DKI) technique.

A total of 37 FEP and 36 matched healthy controls underwent DKI, diffusion tensor imaging (DTI) and T1-weighted magnetic resonance imaging, to estimate mean kurtosis representing microstructural complexity in each segment of the thalamus from DTI connectivity-based segmentation. We also investigated the relationship with psychopathology.

The mean kurtosis in the thalamic nuclei in high connection with the orbitofrontal cortex (F = 8.40, P < 0.01) and the lateral temporal cortex (F = 8.46, P < 0.01) were significantly reduced in FEP compared to healthy controls. However, these mean kurtosis values were not correlated with the clinical scores.

This observed pattern of reduced microstructural complexity in specific regions of the thalamus not only highlights the involvement of the thalamus, but also its network specific microstructural alteration from the early stage of schizophrenia. This finding adds evidence of nucleus specific thalamic defects related to the pathophysiology and it warrants more detailed investigation of the thalamus at the nuclei level in future biomarker studies.