The brain topological alterations in the structural connectome and correlations with clinical characteristics in type 1 narcolepsy

Objective: To explore topological alterations of white matter (WM) structural connectome, and their associations with clinical characteristics in type 1 narcolepsy (NT1).

Methods: 46 NT1 patients and 34 age- and sex-matched healthy controls were recruited for clinical data and diffusion tensor imaging collection. Using graph theory analysis, the topology metrics of structural connectome, rich club organization, and connectivity properties were compared between two groups. Furthermore, partial correlation analysis was performed between the network characteristics of 90 nodes or weakened edges and clinical data using Pearson or Spearman correlation, controlling by age and sex.

Results: Between-group comparison reflected that NT1 patients exhibited sleep disorders with comorbidities of impaired cognition and psychological problems. In patients, the global efficiency, local efficiency, and average clustering coefficient were significantly lower, whereas characteristic path length was larger compared to healthy control. Pertinently, nodal path length of left middle frontal gyrus was positively correlated with Pittsburgh Sleep Quality Index scores. The rich club analysis identified six affected nodes: bilateral dorsolateral superior frontal gyrus, bilateral supplementary motor area, left hippocampus, and left pallidum. Furthermore, six significantly weakened structural connections seeding from these rich club nodes have shown significant correlations with clinical index or polysomnography parameters.

Conclusion: In NT1 patients, WM structural connectome has shown to be disrupted, which were primarily distributed in frontal-parietal cortex, subcortical regions, and particularly cingulate, potentially affecting their clinical manifestations.