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Depression helps the immune system fight infections
Last reviewed: 01.07.2025
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Depression could have arisen as a support for the immune system: during illness, it changes our behavior so that the immune system can more easily cope with the infection. When you have a cold, bed rest and... depression help!When you have a cold, bed rest and... depression help!
According to statistics, about one in ten adults in the United States suffers from depression. There is certainly little pleasant about it, but its widespread prevalence makes scientists increasingly think that depression may have its advantages. Otherwise, it would not be so firmly “sewn” into our brains.
In a paper published in the journal Molecular Psychiatry, its authors, two American psychiatrists, suggest that depression and the immune response to infection have evolved hand in hand.
Researchers have been talking about the connection between depression and the inflammatory immune response for several decades. It is known, for example, that people suffering from depression have a more “irritable” immune system; they may develop a focus of inflammation even in the absence of infection. On the other hand, a high level of molecular markers of inflammation is not necessarily a consequence of depression. In their article, Andrew Miller from Emory University and Charles Raison from the University of Arizona write that mutations that determine a tendency to depression often affect not only the psychoneurological state, but also the immune system. The authors offer a rather bold conclusion that depression could have arisen as a by-product of the evolutionary debugging of the immune system, but at the same time it turned out to be unexpectedly useful in the immune system’s fight against infections.
Depression changes our behavior: we avoid society, lose our appetite, become apathetic, and feel constantly tired. And this comes in handy during illness: firstly, all resources are spent only on the immune response, and not on extraneous activity, and secondly, we spread less infection around us and receive fewer new portions of the pathogen. In those days, when there were no effective drugs, depression could well save a person from death in the case of an infectious disease - by correcting the patient's behavior. This theory also explains well why stress is one of the main causes of depression. Stress accompanies a conflict situation, which in human ancestors could easily escalate into a fight. A fight is inevitable wounds, and wounds are an infection. So, it turns out that stress prepares the body in advance for the fact that it will soon have to indulge its immunity and greatly reduce its activity.
And even sleep disturbances, which are observed both in depression and in an intense inflammatory response, also fit well into the theory under consideration: during illness, a predator can easily overtake the patient, so it is important to detect it first. And in order to detect it in time, you need to be awake more.
This hypothesis, of course, requires verification, but if it is confirmed, then perhaps depression and autoimmune diseases can be treated with the same drugs.
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