Glymphatic function and choroid plexus volume is associated with systemic inflammation and oxidative stress in major depressive disorder

Background

Inflammatory processes were recognized as key factors in the pathophysiology of major depressive disorder (MDD). The choroid plexus (ChP) and glymphatic system played central roles in immune interactions between the brain and periphery. However, their specific roles in MDD and their relationship with systemic inflammation and oxidative stress remained unclear.

Methods

This study finally included 665 MDD patients and 338 healthy controls. Clinical data and MRI scans were collected, and some patients also underwent blood routine and biochemical tests. ChP volume was manually segmented, and the diffusion tensor imaging along the perivascular space (DTI-ALPS) index, reflecting glymphatic function, was obtained through the FSL pipeline. The differences in these dices between groups were compared, and their associations with systemic inflammation and oxidative stress were analyzed.

Results

MDD patients showed increased ChP volume (total: d = 0.316, p < 0.001; left: d = 0.317, p < 0.001; right: d = 0.268, p = 0.003) and decreased DTI-ALPS index (d = −0.144, p = 0.022), with a negative correlation between them (ρ = −0.135, p < 0.001). In MDD patients, lower DTI-ALPS index was correlated with higher LHR (ρ = −0.107, p = 0.025) and MHR (ρ = −0.126, p = 0.008). Larger right ChP volume was associated with higher MLR (ρ = 0.107, p = 0.009), SIRI (ρ = 0.086, p = 0.036), PIV (ρ = 0.086, p = 0.036), MHR (ρ = 0.136, p = 0.004), and PHR (ρ = 0.126, p = 0.008), while larger total ChP volume was correlated with higher MHR (ρ = 0.097, p = 0.042) and PHR (ρ = 0.114, p = 0.017).

Conclusion

MDD appeared to be accompanied by an increase in ChP volume and a decrease in glymphatic function, and these changes were related to systemic inflammation and oxidative stress.