Altered functional connectivity and spatiotemporal dynamics in individuals with sleep disorders

Area of Science:

• Neuroscience
• Sleep Medicine
• Medical Imaging

Background:

• Idiopathic hypersomnia (IH) and narcolepsy type 1 (NT1) cause excessive daytime sleepiness but lack shared biomarkers.
• Understanding the distinct pathophysiology of IH is crucial for targeted treatments.
• Functional connectivity differences may explain symptom variations and nap responses.

Purpose of the Study:

• To compare functional brain connectivity in individuals with IH, NT1, and healthy controls.
• To investigate the impact of a nap on functional connectivity in these groups.
• To identify neural correlates of non-restorative sleep in IH.

Main Methods:

• fMRI BOLD signal analysis comparing static functional connectivity and quasi-periodic patterns (QPPs).
• Inclusion of baseline and post-nap scanning conditions.
• Comparison of three groups: IH, NT1, and healthy controls.

Main Results:

• NT1 group showed higher baseline subcortical connectivity.
• IH group exhibited reduced connectivity at baseline and post-nap, though not statistically significant after correction.
• Significant differences in the Dorsal Attention Network (DAN) and Frontoparietal Control Network (FPCN) correlations were found in IH patients between baseline and post-nap conditions, a pattern unique to IH.

Conclusions:

• Key arousal networks, specifically DAN and FPCN, are significantly disrupted in IH patients.
• The altered functional connectivity in IH is not ameliorated by napping, suggesting a disorder-specific disruption.
• Findings highlight distinct neural underpinnings of sleepiness in IH compared to NT1.