Among AD patients, the baseline plasma MCP-1 level in very mild AD patients (Clinical Dementia Rating (CDR) = 0.5) was 232.6 ± 86.7 μg/ml, that in mild AD patients (CDR = 1) was 240.2 ± 99.6 μg/ml, that in moderate AD patients (CDR = 2) was 246.4 ± 97.2 μg/ml, and that in severe AD patients (CDR = 3) was 342.8 ± 157.1 μg/ml. The gene discussed is CCL2; the disease is Alzheimer disease.