CCL17 and Alzheimer disease: Taking the whole AD group (Group 1 and 2) into statistical analysis we found no correlation between serum levels of analyzed parameters and patients' age, while doing the same analysis for whole control group (Control 1 + Control 2) we found negative correlations between age of the subjects and the following proteins: CCL-17, CCL-22 and IL-18 (r = −0.38, P = .01; r = −0.67, P = .000002; r = −0.3, P = .045; resp).