Both patients with AD and with PD showed statistically significantly higher levels of interleukin IL-6 compared to the control group: p-value of 0.0034 for AD (SMD, 1.17; 95% CI, 0.39-1.96) and p-value of 0.0487 for PD (SMD 0.29 95% Cl 0.00-0.59). Here, IL6 is linked to Parkinson disease.