Research of the last decade established that inflammatory reactions are involved in the pathogenesis of Alzheimer's disease (AD) and schizophrenia (Sch).

The aim of this paper to carry out a comparative analysis of some inflammation mediators [activity of leukocyte elastase (LE) and alpha 1- proteinase inhibitor (α1-PI), the level of CRP, IL-6 and IL-10] in the blood serum in patients with AD and in old aged patients with schizophrenia in comparison with healthy control of the same age.

There were a significant increase in activity of α1-PI, level of CRP, IL-6 and IL-10 (p<0.0001, p<0.05, p<0.01, p<0.01, respectively) and significant decrease of LE activity (p<0.0001) in the group of patients with AD compared to control. The activity of LE was positive correlated with MMSE scores (r =0.34, ?=0.0487) and the IL-6 level was negative correlated with MMSE scores (r =-0.46, ?=0.0077), ie cognitive decline was associated with decreased activity of LE and increased levels of IL-6. The group of patients with Sch was characterized only by a significant increase in activity α1-PI and level of CRP compared to control (p<0.0001, p<0.01, respectively). LE activity and IL-6 level in patients with AD significantly differ from patients with schizophrenia (p<0.05, p<0.01, respectively).

Thus, the low activity LE and high levels of IL-6 are observed only for patients with AD, but not for patients with schizophrenia. These parameters may serve as biological markers of the severity of AD.