The association between systemic inflammation and cognitive performance in the elderly: the Sydney Memory and Ageing Study

Inflammation may contribute to cognitive decline and dementia. This study examined the cross-sectional relationships between markers of systemic inflammation (C-reactive protein, interleukins-1 beta, -6, -8, -10, -12, plasminogen activator inhibitor, serum amyloid A, tumour necrosis factor-alpha and vascular adhesion molecule-1) and cognitive function in 873 non-demented community-dwelling elderly participants aged 70-90 years. Regression analyses were performed to determine the relationships between cognitive domains and inflammatory markers, controlling for age, sex, education, cardiovascular risk factors, obesity and other metabolic factors, smoking, alcohol consumption, depression and presence of the apolipoprotein epsilon 4 genotype. Regression analyses were repeated using four factors derived from a factor analysis of the cognitive tests. After Bonferroni correction for multiple testing, associations remained between raised levels of interleukin-12 and reduced performance in processing speed. Marked sex differences were noted in the abovementioned findings, with only females being significantly affected. Using the four factors derived from the factor analyses of cognitive test as dependent variables, interleukins-12 and -6 were both associated with the processing speed/executive function factor, even after controlling for relevant confounding factors. Thus, markers of systemic inflammation are related to cognitive deficits in a non-clinical community-dwelling elderly population, independent of depression, cardiovascular or metabolic risk factors, or presence of apolipoprotein epsilon 4 genotype. Additional research is required to elucidate the pathophysiology and longitudinal development of these relationships.