High Sensitivity C-Reactive Protein as a Potential Biomarker of Neuroinflammation in Major Psychiatric Disorders

Background: The bidirectional relationship between psychiatric disorders and immune dysregulation has been increasingly documented. Moreover, most major mental diseases are notoriously associated with higher prevalence of cardiovascular and metabolic comorbidities. C-Reactive Protein (CRP) emerged as a crucial biomarker in the stratification of cardiovascular risk. Objectives: Reviewing the recent literature upon: neuroinflammation in mood and schizophrenic disorders, the potential use of HSCRP as an inflammatory biomarker in psychiatric disorders and its possible use for the stratification of risk. Method: The authors conducted a MedLine/PubMed search of all articles up to January 2017 using five keywords. The search was supplemented with a manual review of relevant references. Evidences assessing the relationship between CRP plasma levels and psychiatric disorders have been reviewed. Result: Elevated High-Sensitivity CRP (HSCRP) plasma levels have been reported specially in mood disorders, mainly in mania and in a subset of patients with Depression. Childhood trauma and suicidal behaviour represent factors that increase illness vulnerability and influence immune responses. The complex interaction amongst immune and endocrine systems, metabolic parameters and psychopharmacological effects enhance difficulty in understanding the directionality of this relationship. Conclusion: The heterogeneity of findings provided by research could suggest the presence of genetically determined or epigenetic factors in a subgroup of individuals who react to stress factors with an inflammatory hyperactivation. HSCRP could represent a useful biomarker to identify patients with greater risk to develop medical comorbidities that could benefit from anti-inflammatory treatments.