Inflammatory marker values may indicate suicidal tendencies

October 21, 2020
Chronic inflammation and depressive disorders may have a common genetic cause. Recent research focuses on the inflammatory marker interleukin-6 (IL-6), which at higher levels has been shown to be a potential risk factor for suicidal behavior.

"We wanted to know whether inflammation shares a common genetic background with individual depressive symptoms and whether it is also partly responsible for their onset," explains Nils Kappelmann from the Max Planck Institute for Psychiatry (MPIP) in Munich. To do this, a team of collaborating scientists from the MPIP, the Ludwig Maximilians University Munich (LMU) and the University of Cambridge analyzed a number of genetic variants. These variants were linked, to among other things, elevated inflammatory values and body mass index (BMI) as markers of metabolic regulatory disorders and obesity. Their results have been published in the renowned journal JAMA Psychiatry.

The team confirmed the hypothesis that regulatory disorders of the immune system and metabolism share a common genetic background with depressive symptoms. Thus, a high BMI appears to be causally related to four depression symptoms of joylessness and lack of interest, changes in appetite, exhaustion and feelings of inadequacy.

"Furthermore, we were surprised to find that increased inflammatory marker levels, especially interleukin-6 (IL-6), indicated an increased risk of suicidality," stated study leader Kappelmann. IL-6 plays a key role in regulating the immune system and is a marker for inflammatory processes in the body.

Immunotherapy vs. antidepressants

Depression manifests itself in a number of different ways with sometimes conflicting symptoms. About a quarter of all patients fall under one subgroup, which is called immuno-metabolic depression. These patients have regulatory disorders of the immune system and metabolism and are typically less likely to respond to classic antidepressants or psychotherapy. Anti-inflammatory agents, such as IL-6-inhibitors, could therefore represent a new approach to pharmacological treatment of depression and the prevention of suicidal tendencies in this subtype.

"These findings show clinical relevance as they can help with early identification of patients who are more likely to respond to immunotherapy than to anti-depressants," says Elisabeth Binder, Director of the MPI. "In addition, the treatment of suicidality may be improved. However, further clinical research is needed in order to establish this".

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