Low-grade inflammation is implicated in the pathogenesis of atherosclerosis, metabolic syndrome, and apathy as a form of vascular depression. We analyzed the brain magnetic resonance imaging findings in 259 community-dwelling older adults (122 men and 137 women, with a mean age of 68.4 years). The serum concentrations of high-sensitivity C-reactive protein (hsCRP) were measured by a quantitative enzyme-linked immunosorbent assay. Logistic regression analysis revealed that the log10 hsCRP value and the presence of a metabolic syndrome were independently associated with confluent but not punctate deep white matter lesions (DWMLs). Path analysis based on structural equation modeling (SEM) indicated that the direct path from the log10 hsCRP to the DWMLs was significant (β = 0.119, p = 0.039). The direct paths from the metabolic syndrome to the log10 hsCRP and to the DWMLs were also significant. The direct path from the DWMLs to apathy (β = -0.165, p = 0.007) was significant, but the direct path from the log10 hsCRP to apathy was not significant. Inflammation (i.e., elevated serum hsCRP levels) was associated with DWMLs independent of common vascular risk factors, while DWMLs were associated with apathy. The present analysis with SEM revealed the more realistic scheme that low-grade inflammation was associated with apathy indirectly via DWMLs in community-dwelling older adults.
Keywords: apathy; magnetic resonance imaging; physical activity; silent stroke; small vessel disease; vascular cognitive impairment; vascular depression; white matter lesions.