Role and Perspectives of Inflammation and C-Reactive Protein (CRP) in Psychosis: An Economic and Widespread Tool for Assessing the Disease

Abstract

Schizophrenia is a major psychotic disorder affecting nearly 23.6 million people globally and greatly impacting the cognitive and social functioning of individuals. Multiple risk factors, including genetic, environmental, and epigenetic factors have been identified. However, the exact mechanism by which some factors aid in the development of schizophrenia is still uncertain. Acute and/or long-standing inflammation has been implicated as both a cause and effect of schizophrenia. Heightened immune responses have been documented in large cohorts of individuals with schizophrenia. While not completely known, multiple hypotheses, such as disruption of the blood–brain barrier, alterations in the kynurenine/tryptophan pathway, and increased microglial activation, have been presented to correlate inflammation with schizophrenic symptoms. Measurement of C-reactive protein (CRP) is a commonly performed and inexpensive test on patients’ serum to determine levels of systemic inflammation in the body. Multiple studies have reported an elevated CRP level in different stages of schizophrenia, indicating its potential to be used as a viable biomarker in the diagnosis and monitoring of schizophrenia along with assessing treatment response to conventional and non-conventional treatment regimens. This review aims to evaluate the role of inflammation, in general, and CRP, in particular, in the pathogenesis of schizophrenia and its potential significance in diagnostic, therapeutic, and preventative approaches towards schizophrenia and psychosis.

Biogenic Amine Levels Markedly Increase in the Aqueous Humor of Individuals with Controlled Type 2 Diabetes

“…Hence, the study of the composition of AH may lead to finding some biomarkers of neuroinflammation of those recently reported for some neurological diseases [ 24 ]. Consistent with the hypothesis of a neuroinflammatory component in diabetes, there was an increase in the level of kynurenine, which is related to microglial activation/neuroinflammation [ 25 , 26 , 27 ]. Our findings are consistent with the increase in 3-OH-kynurenine in the CSF of an experimental diabetic encephalopathy model in rats [ 28 ].…”

Shared genetic components between metabolic syndrome and schizophrenia: Genetic correlation using multipopulation data sets

“…However, despite a nonsignificant trend, we stressed that one of the best P ‐values (q‐value) was obtained in the instrumental variables from CRP of the EUR population (q‐value IVW = 0.0514, Egger intercept = 0.389). This is not surprising because several studies have suggested that CRP is a potential biomarker for diagnosis, treatment response, and prevention of SCZ 38 . Specifically, previous clinical studies, including those with a cross‐sectional design, have shown that patients with SCZ had higher CRP values compared with the control group 39–45 .…”

“…This is not surprising because several studies have suggested that CRP is a potential biomarker for diagnosis, treatment response, and prevention of SCZ. 38 Specifically, previous clinical studies, including those with a cross-sectional design, have shown that patients with SCZ had higher CRP values compared with the control group. [39][40][41][42][43][44][45] However, such a study design contains bias, which could be associated with the "status" of SCZ.…”

Potential Inflammatory Biomarker in Patients with Attention Deficit Hyperactivity Disorder

“…The KP pathway is initiated either by tryptophan-2,3-dioxygenase (TDO) in the liver to open the TRP indole ring, or indole-2,3-dioxygenase (IDO) in the brain to produce an instable metabolite of N -formylkynurenine [ 40 , 41 ] ( Figure 2 ). The conversion of N-formylkynyrenine to L-kynurenine (KYN) is then followed.…”