Plasma cytokines profile in older subjects with late onset Alzheimer's disease or vascular dementia

Some cytokines have been involved in the pathogenesis of late onset Alzheimer's disease (LOAD). A possible increase in plasma cytokines levels has been reported in LOAD and vascular dementia (VD), but the results of previous studies are conflicting. We evaluated the plasma levels of IL-6, TNF-alpha, IL-1 beta, and IL-10 in four groups of older individuals: 60 patients with LOAD, 80 patients with VD, 40 subjects with cerebrovascular disease but without dementia (CDND), and 42 controls (C). By analysis of covariance (adjustment for age, gender, coronary heart disease, diabetes, hypertension, smoking, and alcohol consumption) we found that: IL-1 beta was higher in VD, LOAD, and CDND compared with controls (P < 0.005). TNF-alpha was higher in VD and LOAD compared to C (p < 0.05), and in VD compared to LOAD (p < 0.03). IL-6 was higher in VD compared with LOAD (p < 0.03). No differences in IL-10 values were found (Kruskal-Wallis, Asymp. Sig. 0.14). By logistic regression analysis, we demonstrated that high levels (defined as above the median) of IL-1 beta and TNF-alpha, but not of IL-6, were associated with increased likelihood of having VD and LOAD compared to C, while high IL-6 levels were associated with a increased probability of having VD, compared with LOAD. Our study support the notion of a low-grade systemic inflammation in older patients with LOAD or VD, characterized by an increase in plasma IL-1 beta and TNF-alpha levels. The high IL-6 levels found in VD might be not a specific finding, as it might come from several conditions including atherosclerosis and related vascular risk factors, comorbidity, and frailty. (c) 2006 Elsevier Ltd. All rights reserved.