Associations Between Nonspecific Blood-Derived Inflammatory Indices and MRI-Derived Frontal Network Degeneration in Progressive Supranuclear Palsy.

BACKGROUND

Progressive supranuclear palsy (PSP) is a primary 4-repeat tauopathy in which neurodegeneration may be accompanied by neuroinflammatory and peripheral immune alterations. Whether peripheral inflammatory activity reflects structural degeneration within vulnerable brain networks remains unclear.

METHODS

This retrospective case-control study included 12 patients with PSP and 12 patients with Parkinson's disease (PD). Automated volumetric analysis of 3-Tesla MRI was performed using volBrain 2.0. Blood-derived inflammatory indices included neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), systemic inflammation response index (SIRI), and red blood cell distribution with coefficient of variation (RDW-CV).

RESULTS

Patients with PSP showed significantly lower normalized superior frontal gyrus and pallidal volumes than patients with PD. Within the PSP group, higher values of selected blood-derived inflammatory indices were associated with lower frontal network volumes. After adjustment for age, MLR was inversely associated with the composite Frontal Network Score (partial r = -0.7333, p = 0.0067, FDR q = 0.020). The strongest regional association was observed between SIRI and medial frontal cortex volume (rho = -0.748, p = 0.0051); however, regional associations did not remain significant after FDR correction.

CONCLUSIONS

Peripheral inflammatory markers were associated with MRI-derived measures of frontal network degeneration in PSP. The association between MLR and the composite Frontal Network Score supports a link between systemic immune alterations and network-level neurodegeneration in PSP.