One in three people diagnosed with a mood disorder for the first time was hospitalized because of an infection, according to a study published in the journal JAMA Psychiatry.
According to the co-author of the work, Dr. Michael Eriksen Benros from the University of Aarhus (Denmark), patients who were admitted to the hospital because of an infection had a risk of developing a mood disorder (or an affective disorder, e.g. depression) in the future by 62%.
In contrast, those who were hospitalized due to autoimmune disease, the increase was 45%. The presence of both conditions in the patient – i.e. infection and autoimmune disease – increased the risk of affective disorder in the future by 135%.
As Dr. Eriksen Benros emphasizes, this relationship was visible regardless of the type of infection or autoimmune disease.
“In other words, it looks like the immune system is somehow involved in the development of these mental disorders,” the researcher comments. This applies to at least some of the patients who suffer from them.
His team, together with researchers from the University of Copenhagen and Johns Hopkins University (USA), analyzed data on over 3,5 million Danes born between 1945 and 1996. In the period from 1977 to 2010, over 91 of them were hospitalized for some mood disorder. It turned out that 32 percent. of this group had previously been hospitalized due to an infectious disease, and 5% – due to auto-aggressive disease.
According to the researchers, the observed relationship can be explained by the fact that infections and inflammation associated with autoimmune diseases affect the brain. It is normally protected by the so-called the blood-brain barrier, formed by the cells of the capillary blood vessels. Its role is to protect the brain from various harmful factors. However, in the event of infection and inflammation, this barrier can become more permeable, which can have negative effects on the central nervous system.
Researchers emphasize that more research is needed to fully elucidate the mechanism responsible for the relationship between the immune system and mood disorders. This knowledge could help develop methods of preventing these mental problems and improve the effectiveness of their treatment, they say. (PAP)
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