Peripheral cytokines and chemokines in Alzheimer's disease.

A chronic inflammatory process has been implicated in the neuropathology of Alzheimer's disease (AD). The present review focuses on the current knowledge of circulating serum and plasma biomarkers of AD that are linked to inflammatory reactions. There is abundant evidence that inflammatory mechanisms within the central nervous system contribute to cognitive impairment via cytokine-mediated interactions between neurons and glial cells. Interleukins 1, 4, 6, 10, 12, 16, and 18, tumour necrosis factor, and several chemokines have been suggested as biomarkers of AD. Nonetheless, data on circulating cytokine levels are somewhat inconsistent with regard to peripheral cytokine dysregulation in AD. In summary, definite statements concerning differences in inflammatory biomarkers between controls and AD patients will require the use of sensitive multiplex assays in large patient groups in conjunction with measures of disease severity.