Montoya et al. demonstrated that serum concentrations of epidermal growth factor (EGF), interleukin 8 (IL-8), interferon γ-induced protein 10 (IP-10), and monocyte chemoattractant protein-1 (MCP-1) were significantly reduced in patients suffering from cognitive decline with pre-existing severe periodontitis [33]. The gene discussed is EGF; the disease is periodontitis.