Abnormal brain functional network dynamics in narcolepsy type 1 patients

To investigate the dynamic functional connectivity in narcolepsy type 1 (NT1) patients and whether clinical features are associated with abnormal connectivity.

We investigated dynamic functional connectivity (dFC) of 80 drug-naïve NT1 patients, 30 idiopathic hypersomnia (IH) patients and 60 age- and sex-matched healthy controls using sliding-window approach, clustering state analysis and graph-theory methods. Relationships between clinical features and abnormal dFC properties were evaluated.

Three dFC brain states were identified to characterize and compare dynamic functional connectivity patterns: a more frequent and sparsely connected State I (46.96%), a less frequent and more strongly connected State Ⅱ (26.3%), and a less frequent and sparsely connected State Ⅲ (26.74%). In NT1 patients, the occurrence of the State Ⅱ increased, corresponding with a prolonged dwell time of State Ⅱ. While State Ⅲ are predominant for IH patients and healthy controls. The occurrence and dwell time of State Ⅲ are negatively correlated with sleep latency in NT1 patients. Additionally, there was a higher variability in the small-world network parameters, suggesting an abnormal global integration of the brain network in both IH and NT1 patients.

The abnormal temporal patterns and functional segregation coupled with the severity of sleepiness and abnormal local integration in topological properties confirmed the vulnerability of functional networks in NT1 patients.