More than estimated depressed patients could have increased activation of their immune system

New research from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King's College London has used an assessment of gene expression involved in the immune response to show that there could be more patients with major depressive disorder or MDD with activated immune systems than research has previously estimated.

By identifying the molecular mechanisms involved in this association, the research could pave the way to better identify those patients with an immune component to their depression which would potentially help to provide more personalised approaches to treatment and management of MDD.

168 participants were sourced from the Biomarkers in Depression Study (BIODEP). 128 of them had a confirmed diagnosis of MDD and they were then divided into three subgroups according to their levels of CRP in the blood.

Researchers analysed the expression of 16 genes whose activation is involved in the immune response. The initial analysis found increased expression of immune-related genes in people with MDD compared to the those without a diagnosis of depression. When comparing MDD patients who did and didn’t have elevated levels of CRP in their blood, there were no differences in the expression of these 16 genes, suggesting this pattern of expression was independent of CRP levels and potentially underlying a different mechanism.

Importantly, researchers then conducted a secondary analysis on all those participants who had CRP values of less than 1, meaning that they are not considered to have any inflammation. The researchers found that participants with MDD and low levels of CRP still had significantly higher expression of immune genes compared to those without a depression diagnosis.

Reference:

Higher immune-related gene expression in major depression is independent of CRP levels: results from the BIODEP study,Translational Psychiatry,DOI 10.1038/s41398-023-02438-x