The Relationship of Inflammatory Markers to Cognitive Function in a Population-Based Sample
C-reactive protein (CRP), Interleukin-18 (IL-18), Monocyte chemoattractant protein (MCP-1), and Lipoprotein-associated phospholipase (Lp-PLA2) are pro-inflammatory blood markers that appear to play critical roles in atherosclerosis and vascular disease, and have been linked to Alzheimer’s Disease, vascular dementia, and subclinical levels of cognitive decline. The present study investigated the relationship of these four inflammatory markers to cognitive function prospectively, and examined the potential impact of vascular risk factors (i.e., hypertension, hyperlipidemia, smoking status, alchol intake, diabetes mellitus, waist circumference, Cystatin C) and APOE 4 as mediators of cognitive function. METHOD AND RESULTS: Participants include 1904 individuals with CRP, IL-18, MCP-1, and Lp-PLA2, vascular risk factor and APOE 4 data collected as part of the Dallas Heart Study I initiated in 1999, who returned to the Dallas Heart Study II (8 years later) who completed the Montreal Cognitive Assessment (MoCA) as part of a larger clinical research protocol. A significant yet weak correlation was found for Lp-PLA2 (r=.09, p<.01) and MoCA scores, with significant correlations only for men (r=.24, p<.01). None of the other inflammatory markers were associated with MoCA scores. An increased number of vascular risk factors was not related to lower MoCA total scores [F(5,1621)=1.56, p=.168)]. The presence of the APOE 4 allele did not impact the relationship between concentrations of blood markers and cognitive function as hypothesized. In logistic regression analysis, only the demographic variables of Caucasian race and education were significant, and decreased the odds of membership into lowest MoCA tertile group. CONCLUSIONS: Results did not support a relationship between mid-life inflammation and vascular risk factors and later cognitive function in this healthy, middle-aged sample. Demographic factors were the only consistent variables associated with cognitive performance. The minimum level of significant inflammation in this sample may have attenuated the results. Follow-up studies to examine progression of inflammation and vascular risk in relation to cognitive function will help to further examine these relationships.