Abnormal white matter integrity in antipsychotic-naïve first-episode psychosis patients assessed by a DTI principal component analysis

Abstract

Introduction: Diffusion tensor imaging (DTI) studies in patients with schizophrenia have shown abnormalities in the microstructure of white matter tracts. Specifically, reduced fractional anisotropy (FA) has been described across multiple white matter tracts, in studies that have mainly included patients treated with antipsychotic medications.

Objective: To compare FA in antipsychotic-naïve patients experiencing a first episode of psychosis (FEP) to FA in healthy controls to demonstrate that the variance of FA can be grouped, in a coincidental manner, in four predetermined factors in accordance with a theoretical partition of the white matter tracts, using a principal components analysis (PCA).

Methods: Thirty-five antipsychotic-naïve FEP patients and 35 age- and gender-matched healthy controls underwent DTI at 3T. Analysis was performed using a tract-based spatial statistics (TBSS) method and exploratory PCA.

Results: DTI analysis showed extensive FA reduction in white matter tracts in FEP patients compared with the control group. The PCA grouped the white matter tracts into four factors explaining 66% of the total variance. Comparison of the FA values within each factor highlighted the differences between FEP patients and controls.

Discussion: Our study confirms extensive white matter tracts anomalies in patients with schizophrenia, more specifically, in drug-naïve FEP patients. The results also indicate that a small number of white matter tracts share common FA anomalies that relate to deficit symptoms in FEP patients. Our study adds to a growing body of literature emphasizing the need for treatments targeting white matter function and structure in FEP patients.

Keywords: Diffusion tensor imaging; First-episode psychosis; Fractional anisotropy; Principal component analysis; Schizophrenia; TBSS.

Figure 1

Regions with fractional anisotropy (FA) reduction in first-episode psychosis compared to healthy controls are presented in red. Regions in green represents those showing no difference between controls and patients and are provided as reference. Results are shown overlaid on the Montreal Neurologic Institute template and the mean FA skeleton.

Figure 2

Fractional anisotropy differences between first-episode psychosis patients and healthy control groups. Results are shown overlaid on the Montreal Neurologic Institute template. For detailed statistics, please refer to Table 2.