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

Laura Orsolini,Simone Pompili,Umberto Volpe,Silvia Tempia Valenta,Virginio Salvi

doi:10.3390/ijms23031616

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.

Highlights

Accepted: 28 January 2022Published: 30 January 2022 Publisher’sNote: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, Switzerland
One of the most widely renowned hypotheses is based on the monoaminergic theory [7], recent researches focused on other pathways, such as the dysregulation of hypothalamus-pituitary-adrenal axis (HPA), genetic susceptibility, and epigenetic modifications, the oxidative stress-induced damage, and the neurodevelopment theory [8,9,10,11,12]
The following inclusion criteria were considered to be included in the present review: (a) studies investigating C-Reactive Protein (CRP) levels in depressive/major depressive disorder (MDD)/Treatment-Resistant Depression (TRD) patients; (b) studies assessing the depressive symptomatology through validated semi-structured clinical interviews and/or rating scales

Summary

Introduction

Accepted: 28 January 2022Published: 30 January 2022 Publisher’sNote: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.Licensee MDPI, Basel, Switzerland. Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. In 2008, the World Health Organization (WHO) ranked depression as the third cause of burden of disease worldwide and projected that it will rank first by 2030. Depression represents the major contributor to suicide deaths, with an incidence of up to 800.000 per year worldwide [3]. It usually manifests in early adulthood, with a mean age onset of approximately 20–25 years [4]. Depression usually occurs 2-fold higher among women than men at all age groups, and several socio-demographic risk factors are implicated in this trend [5,6]. One of the most widely renowned hypotheses is based on the monoaminergic theory [7], recent researches focused on other pathways, such as the dysregulation of hypothalamus-pituitary-adrenal axis (HPA), genetic susceptibility, and epigenetic modifications, the oxidative stress-induced damage, and the neurodevelopment theory [8,9,10,11,12]

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