The clarification of the connection between inflammation, metabolic dysregulation and specific depressive symptoms was the aim of a current study by researchers from the Max Planck Institute for Psychiatry (MPI) in Munich, the Ludwig Maximilian University of Munich (LMU) and the University of Cambridge. The study showed that the inflammation marker interleukin-6 is causally related to suicidal tendencies, the research team reported on the study results in the journal “JAMA Psychiatry”.
Depression can have different causes and to this day many connections are only insufficiently understood. The role that inflammation can play in depression was made clear in a recent study. The risk of suicide increases with the values of a certain inflammation marker.
Depression can manifest itself in very different ways, with sometimes contradictory symptoms, explain the researchers. In a subgroup, which is called immuno-metabolic depression and accounts for about a quarter of all depression diseases, regulatory disorders of the immune system and metabolism are observed. Often the affected persons respond less well to classical antidepressants or psychotherapy, which makes treatment considerably more difficult.
Disorders of the immune system and metabolism
Whether inflammations (as an indication of regulatory disorders of the immune system) share a common genetic background with individual depressive symptoms, and whether they are even partly responsible for their development, has now been investigated in more detail by the team headed by study director Nils Kappelmann at the MPI. To this end, the researchers first analyzed a number of genetic variants that are associated, among other things, with increased inflammation values and the body mass index as a marker for obesity or regulatory disorders of the metabolism.
“The team was able to confirm the thesis that regulatory disorders of the immune system and metabolic metabolism have a common genetic basis with depressive symptoms,” reports the MPI. Furthermore, a high BMI seems to be causally related to four depression symptoms, namely anhedonia (lack of joy and interest), changes in appetite, exhaustion and feelings of inadequacy.
Although this association with the depression symptoms could not be established for the inflammation markers, an association with the risk of suicide was demonstrated instead. “We were surprised that elevated inflammation values, especially interleukin-6 (IL-6), give an indication of an increased risk of suicidal tendencies,” emphasizes study leader Kappelmann.
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“These findings have clinical relevance, as they can help to identify early on those patients who respond better to immunotherapy than to antidepressants,” adds MPI Director Elisabeth Binder. In addition, treatment with anti-inflammatory drugs (especially IL-6-inhibiting drugs) could become a new approach to drug therapy of depression or suicide prevention. However, further clinical research is still required for this. (fp)
Biomarkers for suicide risk in depression
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