Widespread alterations of diffusion tensor imaging metrics in patients with schizophrenia without current auditory hallucinations

BackgroundStudies have linked auditory hallucinations (AH) in schizophrenia-spectrum disorders (SCZ) to altered cerebral white matter microstructure within the language and auditory processing circuitry (LAPC). However, the neuroanatomical distribution and specificity to the LAPC remains unclear. Here, we investigated the relationship between AH and DTI among patients with SCZ using diffusion tensor imaging (DTI). MethodsWe included patients with SCZ with (AH+; n=59) and without (AH-; n=81) current AH, and 140 age-and-sex-matched controls. Fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were extracted from 39 fibre tracts. We used principal component analysis (PCA) to identify general factors of variation across fibre tracts and DTI metrics. Regression models adjusted for sex, age, and age2 were used to compare tract-wise DTI metrics and PCA factors between AH+, AH-, and healthy controls and to assess associations with clinical characteristics. ResultsWidespread differences relative to controls were observed for MD and RD in patients without current AH. Only limited differences in two fibre tracts were observed between AH+ and controls. Unimodal PCA factors based on MD, RD, and AD, as well as multimodal PCA factors, differed significantly relative to controls for AH-, but not AH+. We did not find any significant associations between PCA factors and clinical characteristics. ConclusionsContrary to previous studies, DTI metrics differed mainly in patients without current AH compared to controls, indicating a widespread neuroanatomical distribution. Our results challenge the notion that altered DTI metrics in the LAPC is a specific feature underlying AH.