George Slavich, a clinical psychologist at UCLA who has studied depression for many years, believes that depression is not only related to psychology, but also to physiology and physical health. First, many inflammation-related diseases exhibit depression-like behaviors, and almost everyone feels pain, fatigue, boredom and immobility when they are sick. This is a protective response acquired in biological evolution, and these manifestations after illness allow us to reduce our activity and preserve our strength to cope with other possible injuries. This manifestation does not differ from that of depressed patients. Whether this similarity of manifestations comes from a common cause, or perhaps there really is a common basis, the first common cause that scientists consider is inflammation. The inflammatory response is a protective measure by the immune system to remove harmful stimuli or pathogens and promote tissue repair, and various pro-inflammatory factors trigger inflammation of body tissues. Both inflammatory cytokine release and the inflammatory response are significantly active during the onset of depression. The effect of inflammatory factors in the periphery is to produce an inflammatory response and in the center is to initiate depression-like behavior. Depressed patients have not only increased inflammatory factors but also an enhanced inflammatory response, and healthy individuals can experience a temporary depressed or anxious state as a result of the inflammatory response to vaccination. Brain imaging studies have found alterations in the brain’s reward-punishment center after typhoid vaccination in patients. Patients with various inflammation-related diseases such as postpartum, diabetes, and stroke are prone to depression, and rheumatoid patients are significantly more likely to experience depression than healthy individuals. To promote an inflammatory response against cancer cells, a interferon is sometimes administered to cancer patients, a condition in which patients often exhibit depression-like side effects. Some scientists have begun to look for the presence of a primary inflammatory disease in depressed patients, and Professor Turhan Canli of SUNY Stony Brook believes that infection is the most likely cause of inflammation (a judgment that seems too arbitrary, especially with the current research boom in metabolic or aseptic inflammation), and he even believes that depression is an infectious disease. Some people are not convinced by this; infection is not the only cause of inflammation; a high-fat, high-sugar diet can promote an inflammatory response, and adding fruits and vegetables or fish to the diet can avoid this inflammation. Obesity is another risk factor for inflammation, probably because adipose tissue, especially distributed around internal organs, contains a high amount of inflammatory factors. In addition, the social isolation or loneliness caused by modern society can also promote an inflammatory response leading to depression-like manifestations, a phenomenon that has been likened to a modern social allergic reaction, which could explain the current worldwide epidemic manifesting itself in binge eating, laziness and self-contained groups, which is essentially an epidemic of chronic inflammatory diseases. Of course we cannot overly suppress the immune response in order to control the inflammatory response, since the immune system is the basis of the body’s defense against disease, but an appropriate control of the system’s inflammation levels should be an ideal strategy. The good news is that clinical studies have found that the combination of anti-inflammatory drugs when administering depression treatment does improve the effectiveness of treating depression. However, controlling chronic inflammation or less intense inflammation does not lend itself to the use of traditional anti-inflammatory drugs such as hormonal or non-hormonal anti-inflammatory drugs, which are effective in controlling inflammation but often have one side effect or another and cannot be used long-term. So people look to nutritional supplements that reduce the inflammatory response such as W3 fatty acids and curcumin, which have the same effect. Perhaps measures such as lycopene, resveratrol, caloric restriction or reduced intake of sulfur-containing amino acids have similar effects.