Tumor necrosis factor‐alpha (TNF‐α) levels, adjusted hippocampal volume (HVa), global 18F‐florbetapir standardized uptake value ratios (SUVR), and cognitive characteristics of the non‐mild cognitive impairment major depressive disorder (MCI MDD), MCI MDD, and the control subjects. This evidence concerns the gene TNF and Cognitive impairment.