Tract-specific white matter changes and their cognitive correlates in obstructive sleep apnea: a cross-sectional study using 3.0 T diffusion tensor imaging.

PURPOSE: Obstructive sleep apnea (OSA) is a common sleep disorder linked to cognitive deficits, while the neuroanatomical substrates remain elusive. Diffusion tensor imaging (DTI) enables in vivo evaluation of white matter (WM) integrity, while tract-specific associations with cognition in OSA need further research. METHODS: A total of 58 participants were enrolled, including healthy controls (HC, n = 14), OSA patients without cognitive impairment (OSA-NC, n = 18), and OSA patients with cognitive impairment (OSA-CI, n = 26). All participants underwent 3.0 T DTI. Fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) values were extracted from 50 predefined WM tracts. MoCA subtests were converted into seven domain Z-scores. Intergroup differences and tract–cognition correlations were analyzed, adjusting for demographics. RESULTS: The OSA-CI group demonstrated widespread FA reductions and MD/RD/AD elevations compared with the HC group, most evident in the corpus callosum, hippocampus, cingulum, fornix, and uncinate fasciculus (p < 0.05). Cognitive impairments were prominent in attention, executive function, and memory domains. Notably, FA in the left uncinate fasciculus was correlated with visuospatial deficits (r=–0.429, p = 0.041), and RD in the right fornix was correlated with delayed recall (r = 0.445, p = 0.033). Additional associations were identified in the genu and external capsule. CONCLUSIONS: DTI-detected WM alterations are linked to domain-specific cognitive deficits in OSA. The corpus callosum, tapetum, and uncinate fasciculus may serve as early imaging biomarkers of cognitive vulnerability.