Combination of serum markers related to several mechanisms in Alzheimer's disease.

Alzheimer's disease (AD) probably involves several pathobiochemical mechanisms and this may be reflected by changes in different serum components. The present study investigated whether the combined analysis of serum molecules related to different mechanisms improves the discrimination of AD patients from healthy controls. Serum of patients with AD was analyzed for a broad spectrum of marker molecules, including 11 inflammatory proteins, 12 sterol intermediates and phytosterols, 2 brain-specific proteins and 4 constituents involved in homocysteine homeostasis. The serum molecule concentrations were combined in a logistic regression model, using a forward stepwise inclusion mode. The results showed that the combination of interleukin-6 (IL-6) receptor, protein alpha1 fraction, cysteine and cholesterol concentrations improved the discrimination between AD patients and healthy controls compared to the single markers. In conclusion, the results of this study have shown that the complex pathology in AD is reflected in a pattern of altered serum concentrations of several marker molecules related to several pathobiochemical mechanisms.