In AD with depression group, a moderate inverse correlation was seen between serum IL 6 levels and MMSE score (r = - 0.47, p = 0.0048), while a strong inverse correlation existed between serum TNF α levels and MMSE scores (r = - 0.65, p = 0.0001) (Fig. 3B, 3C). Here, TNF is linked to depressive symptom measurement.