Microstructural white-matter correlates of hallucination proneness in healthy adults: Diffusion tensor metrics and arcuate fasciculus tract asymmetry

Hallucination proneness exists on a continuum in the general population; if common mechanisms span health and illness, white-matter features that distinguish patients from controls should also covary with subclinical proneness. In healthy adults (n = 68), we related Launay-Slade Hallucination Scale (LSHS) sub-scores to diffusion tensor imaging (DTI) metrics, fractional anisotropy (FA), mean (MD), axial (AD), and radial diffusivity (RD) using region-of-interest analyses of major association pathways and subject-specific arcuate fasciculus (AF) tractography with lateralization indices. Higher general proneness (LSHS-modified) was associated with lower AD in posterior association pathways right ILF (ρ = - 0.32, p = 0.0075), bilateral SLF (left: ρ = -0.32, p = 0.0072; right: ρ = - 0.24, p = 0.0481) and occipital lobe (ρ = -0.26, p = 0.0314), while RD showed no relationship with the visual sub-score. In AF tractography, left AF showed modest negative associations with MD (ρ = -0.25, p = 0.0399) and AD (ρ =-0.27, p = 0.0250), whereas FA, tract volume/length, and lateralization were not significantly related to LSHS scores; AF lateralization remained leftward on average. These results indicate that subclinical proneness tracks selective microstructural variation (lower AD/MD) in posterior visual-language pathways, whereas canonical AF features widely emphasized in patient studies (microstructure, tract size, leftward asymmetry) did not covary with proneness in health, suggesting those AF abnormalities may index broader psychosis vulnerability rather than the propensity to hallucinate per se.