In addition, mental and psychological factors such as stress, anxiety, and depression may affect intestinal microecology and immune function to induce the onset and aggravation of IBS.[60,61] Inflammatory factors such as Interleukin-1 (IL-1), C-reactive protein, and IL-6 are significantly increased in the peripheral blood of patients with anxiety and depression,[62,63] suggesting that anxiety and depression may induce inflammation. Here, CRP is linked to major depressive disorder.