C-Reactive Protein as a Biomarker for Major Depressive Disorder?

Abstract

The etiopathogenesis of depression is not entirely understood. Several studies have investigated the role of inflammation in major depressive disorder. The present work aims to review the literature on the association between C-Reactive Protein (CRP) and depression. A systematic review was performed for the topics of ‘CRP’ and ‘depression’ using the PubMed database from inception to December 2021. Fifty-six studies were identified and included in the review. Evidence suggested the presence of dysregulation in the inflammation system in individuals with depression. In most studies, higher blood CRP levels were associated with greater symptom severity, a specific pattern of depressive symptoms, and a worse response to treatment. Moreover, about one-third of depressed patients showed a low-grade inflammatory state, suggesting the presence of a different major depressive disorder (MDD) subgroup with a distinct etiopathogenesis, clinical course, treatment response, and prognosis, which could benefit from monitoring of CRP levels and might potentially respond to anti-inflammatory treatments. This work provides robust evidence about the potential role of CRP and its blood levels in depressive disorders. These findings can be relevant to developing new therapeutic strategies and better understanding if CRP may be considered a valuable biomarker for depression.

The severity of depression is associated with pelvic inflammatory diseases: A cross-sectional study of the United States National Health and Nutrition Examinations from 2013 to 2018

“…Inflammation, or inflammatory reaction, is caused by the activation of the immune system, usually characterized by local reactions caused by stimulation, injury, or infection, accompanied by symptoms such as redness, swelling, heat, and pain ( 6 ). Redness, swelling, heat, and pain were commonly associated with local reactions caused by stimulation, injury, or infection ( 7 ). In patients with severe depression, the abnormal expression of glucocorticoid receptors is related to inflammation ( 8 ).…”

Mendelian randomization analysis identified causal Association of Childhood Obesity with adult major depressive disorder

“…44 A recent systematic review from 56 studies provides robust evidence about the potential role of CRP in the development of adult MDD. 45 Finally, it has been proposed that the co-occurrence of obesity and MDD may have a genetic basis. For example, association study has revealed that NPY2R gene was associated with both childhood obesity and adulthood MDD.…”

Molecular pathways of major depressive disorder converge on the synapse

“…Indeed, a heightened inflammatory response is linked to MDD. Specific proinflammatory cytokines and their receptors associated with MDD include interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-1β, IL-2, IL-2 receptor, IL-4, IL-10, the IL-1 receptor antagonist, the transforming growth factor-β, and C-reactive protein (CRP) [ 127 , 128 ]. Proinflammatory cytokines also correlate with MDD symptom severity [ 129 ] and CRP with treatment-response [ 130 ].…”