As shown within Figure 2A and Table 2, serum IL-17 levels were significantly increased in AD (68.06 ± 17.49 ng/ml, P < 0.001) and MCI (56.51 ± 9.34 ng/ml, P = 0.003) patients as compared with controls (41.50 ± 14.65 ng/ml). Here, IL17A is linked to Alzheimer disease.