Neurite Imaging Reveals Widespread Alterations in Grey Matter Neurite Morphology in Obstructive Sleep Apnoea.

Obstructive sleep apnoea (OSA) is a common chronic multisystem disorder, and cortical structural alterations have been detected via conventional neuroimaging techniques. Recent advances in diffusion-weighted imaging have yielded novel techniques for investigating neural microstructure, which may potentially offer supplementary insights into neurodegenerative processes associated with OSA. In the present study, we employed the neurite orientation dispersion and density imaging (NODDI) model to explore cortical microstructure in patients with OSA. Multi-shell diffusion magnetic resonance imaging (MRI) was acquired to fit the NODDI diffusion models. Scanned participants included individuals with mild OSA (n = 24), moderate OSA (n = 26), severe OSA (n = 23) and healthy controls (n = 24). Grey matter-based spatial statistics (GBSS) were used to compare NODDI-derived microstructural measures, orientation dispersion index (ODI) and neurite density index (NDI), among the four groups. The results demonstrated significant alterations (both increases and decreases) in NODDI metrics across OSA groups with different severity levels, with relatively more pronounced and widespread ODI changes observed compared with those of NDI. Our findings suggest a potential association between OSA and widespread alterations in grey matter cytoarchitecture. Neurite parameters provide important insights into the microstructure of grey matter in OSA.