Evaluation of glymphatic system dysfunction in patients with insomnia via diffusion tensor image analysis along the perivascular space.

Background: The glymphatic system is a crucial pathway for the clearance of metabolic waste from the brain, and its dysfunction has been linked to various neurodegenerative disorders. This study examined the connection between insomnia and glymphatic system dysfunction, offering a novel perspective on the pathophysiological mechanisms underlying insomnia.

Methods: We prospectively recruited 25 patients with insomnia and 37 healthy controls for a case-control study. All participants underwent routine magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) scans. Glymphatic activity was measured via diffusion tensor image analysis along the perivascular space (DTI-ALPS). All patients with insomnia underwent a polysomnogram (PSG) examination and were evaluated using the Pittsburgh Sleep Quality Index (PSQI). We used United Imaging Healthcare artificial intelligence to count the number of enlarged perivascular spaces (ePVSs) in the centrum semiovale, corona radiata, basal ganglia, and hippocampal regions.

Results: The left ALPS index, right ALPS index, and average ALPS index were found to be lower in the insomnia group than in the control group [P false discovery rate (P)=0.002, 0.002, and 0.002]. There was no difference in the ALPS index between the left and right sides (P>0.05) in healthy control group, insomniac group, or the entire cohort. The average ALPS index was correlated with the proportion of rapid eye movement and N1 stage sleep (r=0.478 and -0.541; P=0.05 and 0.03). The number of ePVSs was not statistically different between groups in the centrum semiovale, the basal ganglia region, the corona radiata region, the hippocampus region, or other regions (P>0.05).

Conclusions: Insomnia is associated with impairments in glymphatic circulation, and the average ALPS index can serve as an imaging biomarker for glymphatic dysfunction in insomnia, aiding in the prevention of further progression to dementia.