Impaired neurovascular-glymphatic functional association in chronic insomnia: Evidence from multimodal BOLD and DTI imaging.

OBJECTIVE

This study used blood oxygen level-dependent functional magnetic resonance imaging (BOLD-fMRI) to assess cerebrovascular reactivity (CVR) and diffusion tensor image analysis along the perivascular space (DTI-ALPS) to evaluate glymphatic activity in chronic insomnia patients, exploring their interrelationship.

METHODS

In this study, we included 55 patients with chronic insomnia and 47 age- and sex-matched healthy controls. The chronic insomnia group was subdivided into mild (n = 17), moderate (n = 20), and severe (n = 18) based on the Insomnia Severity Index. All participants underwent conventional MRI, 3D-BRAVO, BOLD, and DTI. Data were analyzed using independent sample t-tests, non-parametric tests, one-way ANOVA, and Spearman's correlation.

RESULTS

The whole-brain CVR was significantly lower in the chronic insomnia group (2.733 [2.346, 3.148]) than in the healthy control group (3.376 [2.867, 4.963]; Z = -5.287, p < 0.001). CVR declined with increasing insomnia severity (p < 0.001). The ALPS-index was also lower in the chronic insomnia group (1.426 ± 0.061) than in the healthy control group (1.637 ± 0.056; t = -15.181, p < 0.001). A positive correlation was observed between the whole-brain CVR and the ALPS-index (r = 0.720, p < 0.001), indicating an association between CVR and glymphatic system function in chronic insomnia.

CONCLUSION

This study suggests that chronic insomnia is associated with impaired CVR and glymphatic system dysfunction, and the link between them merits further investigation.