Elevated C-reactive protein is associated with sensory gating deficit in schizophrenia

Executive functioning trajectories and their prospective association with inflammatory biomarkers in schizophrenia and non-psychiatric comparison participants

BACKGROUND AND HYPOTHESIS

Cognitive change in people with schizophrenia (PwS) is challenging to assess, but important to understand. Previous studies with limited age ranges and follow-up were subject to practice effects. Controlling for practice effects in a well-established cohort, we examined executive functioning trajectories and their association with inflammatory biomarkers, hypothesizing that PwS will have worsening executive functioning over time compared to non-psychiatric comparison participants (NCs), predicted by higher baseline inflammation with a stronger relationship in PwS than NCs.

STUDY DESIGN

Executive functioning was assessed in 350 participants (n = 186 PwS, 164 NCs) at 12-16-month intervals (0 to 7 follow-up visits). Inflammatory biomarkers at baseline included high sensitivity C-Reactive Protein (hs-CRP), Interferon-gamma, Tumor Necrosis Factor (TNF)-alpha, and Interleukin(IL)-6, -8, and - 10. Executive functioning trajectories across diagnostic groups were estimated using a linear mixed-effects model controlling for age, sex, race/ethnicity, and education level, with additional models to assess prediction by baseline inflammation.

STUDY RESULTS

Over 4.4 years average follow-up, improvements in executive functioning were attenuated in PwS and older participants. Controlling for practice effects negated improvements, revealing declines among highly educated participants regardless of diagnosis. Higher baseline hs-CRP predicted worse executive functioning only among NCs, while TNF-alpha was predictive of change in all participants only after controlling for practice effects. Only the main effect of hs-CRP on executive function was significant after adjusting for multiple comparisons. None of the other inflammatory biomarkers predicted executive functioning or trajectories of performance among study participants.

CONCLUSIONS

Systemic inflammation as reflected by baseline inflammatory biomarker levels did not predict longitudinal declines in executive functioning. Additional studies examining the temporal dynamics of inflammation and cognition in PwS will help further clarify their relationship and associated mechanisms.

C-Reactive Protein (CRP): A Potent Inflammation Biomarker in Psychiatric Disorders

An increasing number of studies have investigated the role of inflammation in psychiatric disorders, by demonstrating how an altered/dysfunctional immunological and inflammatory system may underpin a psychiatric condition. Particularly, several studies specifically investigated the role of a neuroinflammatory biomarker, named C-reactive protein (CRP), in psychiatric disorders. Overall, even though scientific literature so far published still does not appear definitive, CRP is more likely reported to be elevated in several psychiatric disorders, including schizophrenia, mood disorders, anxiety disorders and post-traumatic stress disorder. Moreover, a low-grade inflammation (CRP >3 mg/L) has been more likely observed in a subgroup of patients affected with a more severe psychopathological symptomatology, more treatment resistance and worst clinical mental illness course, strengthening the hypothesis of the need for a different clinical and prognostic characterization based on this concomitant neuroinflammatory predisposition. However, even though further research studies are needed to confirm this preliminary evidence, CRP may represent a potential clinical routine biomarker which could be integrated in the clinical routine practice to better characterize clinical picture and course as well as address clinicians towards a personalized treatment.

A systematic review and meta-analysis of abnormalities in hematological and biochemical markers among Bangladeshi COVID-19 cases

Background and Aims

Abnormalities in hematological and biochemical markers are assumed to be associated with the progression of COVID-19 disease. This meta-analysis was performed to assess the consequences of abnormalities of biomarkers (D-dimers, C-reactive protein [CRP], serum ferritin, lactate dehydrogenase [LDH], random blood sugar [RBS], absolute neutrophil count [ANC], neutrophil to lymphocyte ratio (NLR), serum creatinine, and hemoglobin) in the Bangladeshi COVID-19 patients.

Methods

The data of biomarker levels in Bangladeshi COVID-19 patients were gathered from five databases: PubMed, ScienceDirect, Web of Science, Google Scholar and Bangladesh Journals Online between January 2020 to March 2022. Review Manager 5.4 was used for the meta-analysis, and Egger's test and Begg-Mazumdar's rank correlation were used to investigate publication bias.

Results

This study included 1542 patients with 567 severe and 975 nonsevere statuses. Based on the accumulated data synthesis, there is a strong correlation between disease severity and different biomarkers, including D-dimer, CRP, ferritin, LDH, RBS, NLR, and serum creatinine (MD = 1.16, p = 0.0004; MD = 22.97, p = 0.003; MD = 419.26, p < 0.00001; MD = 118.37, p = 0.004; MD = 1.96, p = 0.02; MD = 1.26, p = 0.02; and MD = 0.31, p = 0.008, respectively). A significantly decreased correlation was observed for hemoglobin levels in severe COVID-19 patients (MD = -0.73, p = 0.10).

Conclusion

The elevated biomarkers level was noticed in severe cases compared to nonsevere patients, revealing that D-dimer, CRP, ferritin, LDH, RBS, NLR, and serum creatinine are significantly correlated to COVID-19 severity. Only lower hemoglobin level was found to be associated with COVID-19 severity.

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

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.

Sex differences in association between cognitive impairment and clinical correlates in Chinese patients with first-episode drug-naïve schizophrenia

BACKGROUND

Schizophrenia is a complex mental illness with significant sex differences. Cognitive impairment is common in patients with schizophrenia, even in remission. This study was designed to examine the sex differences in the relationship between cognitive impairment and clinical correlations with first-episode drug-naïve (FEDN) schizophrenia.

METHODS

93 FEDN patients (male/female = 45/48) and 160 controls (male/female = 74/86) were enrolled to compare the sex differences in cognitive functions measured by the MATRICS Consensus Cognitive Battery (MCCB). Positive and Negative Syndrome Scale (PANSS) and Hamilton Depression Scale (HAMD) were used to evaluate patients' clinical symptoms. We compared cognitive impairment with sociodemographic characteristics and measures of different genders, as well as group-by-sex interactions.

RESULTS

Our results showed that male patients had significantly lower scores for symbol coding, digital sequence, and verbal learning than female patients, while the healthy controls showed similar sex differences. In female patients, multiple linear regression analysis confirmed that PANSS negative symptoms and general psychopathology scores, HAMD total score, and education level were independent contributors to MCCB total score. In male patients, only education was an independent contributor to MCCB total score.

CONCLUSIONS

These findings revealed significant sex differences in cognitive impairments and clinical symptoms in FEDN, which will be worthy of a follow-up study of schizophrenia in the future.

P50 inhibition deficit in patients with chronic schizophrenia: Relationship with cognitive impairment of MATRICS consensus cognitive battery

OBJECTIVE

Cognitive impairment is a core symptom of schizophrenia (SCZ); however, its pathophysiological mechanisms remain unclear. The sensory gating (SG) deficits reflected by P50 inhibition are recurring in SCZ, and this inhibition may be related to the cognitive deficits seen in these individuals. This study aimed to investigate the relationship between P50 inhibition and cognitive dysfunction in SCZ, which has not been fully investigated up to this point.

METHODS

A total of 270 individuals with chronic SCZ and 116 healthy controls were enrolled in the study. Psychopathology of SCZ was rated by the positive and negative syndrome scale (PANSS), while cognitive function and P50 inhibition of subjects were assessed by the MATRICS Consensus Cognitive Battery (MCCB) and the electroencephalography system.

RESULTS

The MCCB total and its 10 index scores were significantly lower in patients than those in healthy controls (all p < 0.001). SCZ patients had a lower amplitude of S1, and higher P50 ratio than healthy controls (both p < 0.01). However, there were no significant correlations between the P50 ratio and any of the PANSS total and its subscale scores in SCZ patients (all p > 0.05). Moreover, no correlation was found between the P50 components and the MCCB scores (all p > 0.05).

CONCLUSIONS

Our findings suggest that the P50 inhibition deficits occur in Chinese individuals with SCZ, which may not be associated with their clinical symptoms and cognitive impairment.

Peripheral inflammatory and neurotrophic biomarkers of cognitive impairment in schizophrenia: a meta-analysis

BACKGROUND

Schizophrenia is associated with significant cognitive impairment. However, the pathophysiological mechanisms underlying cognitive dysfunction in schizophrenia remain unclear. Brain-derived neurotrophic factor (BDNF) and C-reactive protein (CRP) are among the most commonly investigated peripheral markers of cognition in schizophrenia.

METHODS

A systematic review in PubMed and Scopus databases was performed until 31 January 2019 to assess the relationship between cognitive impairment, CRP and BDNF levels in schizophrenia. A random-effects meta-analysis was conducted.

RESULTS

Current meta-analysis included 21 studies including 2449 patients with schizophrenia-spectrum disorders. Overall, both BDNF [r = 0.12, confidence interval (CI) 0.04-0.19] and CRP (r = -0.13, CI 0.08-0.18) levels were very modestly but significantly related to cognitive functioning in schizophrenia (r = 0.12, CI 0.04-0.19). In meta-analyses of cognitive domains, BDNF levels were significantly associated with verbal memory (r = 0.16, CI 0.09-0.23), working memory (r = 0.14, CI 0.06-0.22), processing speed (r = 0.18, CI 0.10-0.26) and verbal fluency (r = 0.09, CI 0-0.18) performances. Elevated CRP levels were related to all cognitive domains (r = -0.09 to -0.13) except for fluency. Subgroup analyses suggested that the relationship between cognitive and BDNF levels were more pronounced in chronic samples.

CONCLUSIONS

Current findings suggest that cognitive impairment in schizophrenia is significantly related to elevated CRP and reduced BDNF levels in schizophrenia, particularly in chronic samples. However, small effect sizes of these correlations suggest that inflammation and decreased BDNF levels do not play a major role in cognitive dysfunction in most patients with schizophrenia. Further studies are needed to investigate the potential intermediating and confounding factors which can influence the level of relationship between inflammation, neurotrophic factors and cognition in schizophrenia.

The interaction between positive schizotypy and high sensitivity C-reactive protein on response inhibition in female individuals

This study aimed to measure the associations between high sensitivity C-reactive protein (hsCRP), childhood maltreatment (CM), schizotypy and response inhibition, and to explore the interactions between hsCRP, CM and schizotypy on response inhibition. Two hundred and fourteen participants completed the Stop-Signal Task (SST), the Schizotypy Personality Questionnaire (SPQ) and the Childhood Trauma Questionnaire-Short Form (CTQ), which measured response inhibition, schizotypy and history of CM respectively. The level of hsCRP was also measured. The high schizotypy group (n = 114) had higher scores on SPQ and CTQ, higher hsCRP levels and longer SST reaction times (SSRTs) than the low schizotypy group (n = 100). In female participants, SSRT had a positive correlation with the SPQ positive factor and the disorganized SPQ factor and a positive correlation with physical neglect. HsCRP was positively correlated with the SPQ negative factor and positive SPQ factor. In male participants, SSRT was negatively correlated with emotional neglect and physical neglect. The majority of correlations between CTQ and SPQ variables were significant in both female and male participants. In female participants, hsCRP significantly predicted SSRT, and hsCRP significantly interacted with positive schizotypy in predicting SSRT.

Associations between C-reactive protein levels and cognition during the first 6 months after acute psychosis

OBJECTIVE

Inverse relationships between the C-reactive protein (CRP) levels and cognitive performance in acute psychosis have been demonstrated. We aimed to investigate how the serum level and initial change of CRP in acutely admitted patients with psychosis was correlated with cognitive performance during a 6-months follow-up period.

METHODS

The study is part of a pragmatic, randomised trial comparing four different second-generation antipsychotic drugs, and consists of 208 acute phase patients recruited at admittance for psychosis. This study reports data for all groups collectively, and does not compare treatment groups. Measurements of CRP and cognitive performance were conducted at baseline (T1) and after 4 weeks on average after inclusion (T2). Cognition was also assessed after 3 months (T3) and 6 months (T4) of follow-up.

RESULTS

Global cognition improved during the follow-up period of 6 months, especially in the T1-T2 interval. The different cognitive subdomains showed different time-dependent profiles of improvement, with memory and attention improving significantly also in the later phases. Reduction of the CRP level during the initial follow-up interval (T1-T2) was associated with increased overall cognitive performance in the T2-T4 interval, but not in the T1-T2 interval. For the cognitive subdomains, we found an inverse association between change in CRP level and verbal abilities (T2-T4 interval), and attention (T2-T3 interval).

CONCLUSION

These findings indicate that initial changes in the serum level of CRP in the acute phase of psychosis may predict cognitive function in later phases of the disease.

Blood levels of interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha and cognitive functions in patients with obsessive compulsive disorder

BACKGROUND

Cognitive dysfunction and immune system disorders are two actual issues for the patients with Obsessive Compulsive Disorder (OCD). The cognitive dysfunctions have been considered to substantial part of clinical phenomenon of OCD but exploration of various etiopathogenesis of cognitive dysfunction is needed. Immune dysfuncion has been implicated to be important part of pathopysiology of OCD and different lines of evidence suggests immune abnormalities in OCD. But whether these immune changes are traits of disease or secondary to clinical burden of the disease such as cognitive dysfunctions has not been determined. Data regarding relation between the cognitive dysfunctions and immune system disorders in OCD is unsatisfied. In this study we aimed to investigate the relation of blood levels of interleukin 1-beta (IL-1ß), interleukin-6 (IL-6) and Tumor Necrosis Factor-α (TNF-α) with various neurocognitive functions in patients with OCD in comparison with its autogenous/reactive subtypes and healthy controls. Further exploration of the effects of various clinical variables on cognitive functioning in patients with OCD and additional investigation of whether the cognitive dysfunction associated with this disorder differs from or overlap with that in other anxiety disorders are needed.

METHODS

Forty-two patient with OCD and 45 age, sex and educational level matched healthy control were enrolled in the study. The diagnosis of OCD was made with Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Yale- Brown Obsessive-Compulsive Scale, Beck Anxiety and Depression Inventory Scales were administered. Neuropsychological test battery including Wisconsin Card Sorting Test (WCST), Trail Making Test A and B (TMT-A, TMT-B) were used for evaluation of the patients and healthy control. The plasma of interleukin-1beta (IL-1ß), interleukin-6 (IL-6), Tumor Necrosis Factor-Alpha (TNF-α) of both groups were measured with ELISA kits.

RESULTS

Blood levels of IL-1ß, IL-6 and TNF-α were significantly higher in patients with OCD than the healthy control. There was significant difference in IL-1ß, IL-6 but not in TNF-α between autogenous/reactive subtypes and healthy controls. TNF-α is positively correlated with TMT-A, TMT-B and Stroop Test Part 5, negatively correlated with immediate memory, verbal learning, interference effect, immediate recall, delayed recall and recognition in RAVLT. IL-1ß was positively correlated with TMT-A score. IL-6 was positively correlated with scores of TMT-A, TMT-B. IL-6 was negatively correlated with immediate memory, verbal learning, interference effect, immediate recall and delayed recall in RAVLT, positively correlated with number of perseverative error and negatively correlated with the number of categories completed in WCST.

CONCLUSION

This is the first study that investigates the relation of IL- 1ß, IL-6 and TNF-α levels with cognitive functions in OCD. There may be a contribution to pathogenesis of OCD and subtypes then new choices for treatment might be developed. Moreover, uncovering the effect of cytokine blood levels on cognitive function of OCD, new data concerning etiopathogenesis and further treatment choices can be gained.

C-reactive protein is associated with severity of thought and language dysfunction in patients with schizophrenia

BACKGROUND

Numerous studies have demonstrated an association between C-reactive protein (CRP) levels and schizophrenia. However, the findings on psychotic severity and cognition remain inconsistent. The relationship between CRP and formal thought disorder in subdomains remains unclear.

METHODS

We enrolled stable patients (defined as those who had no treatment changes during the 4-week period before evaluation) with a diagnosis of schizophrenia or schizoaffective disorder, according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. We used the 30-item Thought and Language Disorder (TALD) scale to evaluate thought and language dysfunction over four subscales. We assessed psychotic symptoms using the Positive and Negative Syndrome Scale (PANSS). We collected fasting venous blood and measured plasma CRP levels.

RESULTS

We enrolled 60 patients with schizophrenia. All patients received TALD and PANSS evaluation, and 33 of them had their CRP levels checked. The multivariate regression analysis indicated that CRP levels were significantly associated with the total score on the TALD (t=2.757, P=0.010) and the TALD Objective Positive subscale (t=2.749, P=0.011), after sex, age, duration of illness (in years), and use of atypical antipsychotics were adjusted for. Additionally, CRP was significantly associated with the PANSS positive subscale (t=2.102, P=0.045). A significantly positive correlation was observed between the total scores on the TALD scale and PANSS (ρ =0.751, P<0.001).

CONCLUSION

Our results suggest that abnormal CRP levels are significantly associated with formal thought and language dysfunction in the Objective Positive subdomain and positive psychotic symptoms.

Cytokines and C-reactive protein alterations with respect to cognitive impairment in schizophrenia and bipolar disorder: A systematic review

BACKGROUND

The aim of this article was to perform a systematic review of studies investigating the association between peripheral levels of cytokines and C-reactive protein (CRP), cytokine gene polymorphisms and cognition in patients with schizophrenia and bipolar disorder (BD).

METHODS

The following databases: PubMed, CINAHL Complete, Academic Search Complete, ERIC and Health Source: Nursing/Academic Edition databases were searched according to the PRISMA guidelines. We included studies that investigated the association between peripheral levels of CRP and cytokines, cytokine gene polymorphisms and cognitive performance in schizophrenia and/or BD patients. Subsequently, quality assessment of eligible publications was performed. Results were synthesized by discussing main findings around correlations between inflammatory markers and cognition.

RESULTS

Most consistent results indicate worse cognitive performance in schizophrenia patients with higher CRP levels. Less consistent evidence suggests better cognitive functioning of schizophrenia patients with higher levels of tumour necrosis factor-α (TNF-α). Evidence for the involvement of other cytokines in cognitive impairment in patients with schizophrenia is less convincing due to discordant results or scarcity of studies. Due to low number of studies, it is difficult to draw conclusions on the involvement of CRP and cytokine alterations in the development of cognitive deficits in BD. Single studies suggest the role of CRP, interleukin(IL)-1 receptor antagonist, IL-6 and TNF-α with its receptors in the development of cognitive impairment in BD.

CONCLUSIONS

Peripheral inflammation might be related to cognitive deficits in schizophrenia and BD. Unequivocal conclusions cannot be made due to methodological heterogeneity and low number of studies investigating particular cytokines.

C-Reactive Protein as a Peripheral Biomarker in Schizophrenia. An Updated Systematic Review

Objectives: The objective of this systematic review was to synthetize the published data on the relationships between elevated blood C-reactive protein (CRP) levels and schizophrenia (SZ) onset risk, illness characteristics and treatments, cognition and physical health. Method: The systematic bibliographic searches have been carried out according to the Cochrane methodology. Medline, web of science, Google Scholar with each database being searched from inception to November 2017. Results: 53 studies were included in the present review. While meta-analyses including case-control studies suggest a clear association between CRP and SZ, one other study has suggested that CRP-associated genes were associated with a lower risk of SZ onset. Increased CRP has been significantly associated with positive symptoms in acute phase psychosis, while studies including community-dwelling stabilized subjects did not find such an association. Abnormal CRP has been associated with a wide range of cognitive impairment in SZ stabilized individuals. Body Mass index has been extensively associated with increased CRP in SZ subjects; and increased CRP has been identified as a risk factor for metabolic syndrome and cardiovascular risk in SZ subjects. Increased CRP has also been associated with high nicotine dependence in SZ smokers and one study has suggested that increased CRP was associated with sedentary behavior. Conclusion: In the light of the above-mentioned studies, increased hs-CRP may be reasonably suggested as a marker for SZ onset risk, as well as a risk factor for increased positive symptoms, cognitive impairment, hypovitaminosis D, microbiota disturbances, cardiovascular and metabolic syndrome risk in SZ subjects, and increased nicotine dependence in SZ smokers. In case of increased CRP levels, anti-inflammatory strategies (add-on anti-inflammatory drugs including aspirin and omega 3 fatty acids, vitamin D supplementation, physical activity, probiotics) should be also further evaluated. Limits: Most of the studies were cross-sectional and cohort studies are needed to determine the temporal relationship between increased CRP and the psychiatric outcomes.

High C-reactive protein levels are associated with depressive symptoms in schizophrenia

BACKGROUND

Depressive symptoms are frequently associated with schizophrenia symptoms. C - Reactive protein (CRP), a marker of chronic inflammation, had been found elevated in patients with schizophrenia and in patients with depressive symptoms. However, the association between CRP level and depressive symptoms has been poorly investigated in patients with schizophrenia. The only study conducted found an association between high CRP levels and antidepressant consumption, but not with depressive symptoms investigated with the Calgary Depression Rating Scale for Schizophrenia (CDSS).

OBJECTIVES

The aim of this study was to evaluate CRP levels and depressive symptoms in patients with schizophrenia, and to determine whether high CRP levels are associated with depressive symptoms and/or antidepressant consumption, independently of potential confounding factors, especially tobacco-smoking and metabolic syndrome.

METHODS

Three hundred and seven patients with schizophrenia were enrolled in this study (mean age = 35.74 years, 69.1% male gender). Depressive symptoms was investigated with the CDSS. Patients were classified in two groups: normal CRP level (≤ 3.0mg/L) and high CRP level (> 3.0mg/L). Current medication was recorded.

RESULTS

124 subjects (40.4%) were classified in the high CRP level group. After adjusting for confounding factors, these patients were found to have higher CDSS scores than those with normal CRP levels in multivariate analyses (p = 0.035, OR = 1.067, 95% CI = 1.004-1.132). No significant association between CRP levels and antidepressants consumption was found.

LIMITATIONS

The size sample is relatively small. The cut-off point for high cardiovascular risk was used to define the two groups. CRP was the sole marker of inflammation in this study and was collected at only one time point. The design of this study is cross-sectional and there are no conclusions about the directionality of the association between depression and inflammation in schizophrenia.

CONCLUSION

This study found an association between high rates of CRP levels and depressive symptoms in patients with schizophrenia, but no association with antidepressant consumption. Further studies are needed to investigate the impact of inflammation in schizophrenia.

Protein-C Reactive as Biomarker Predictor of Schizophrenia Phases of Illness? A Systematic Review

BACKGROUND

Schizophrenia is a complex illness in which genetic, environmental, and epigenetic components have been implicated. However, recently, psychiatric disorders appear to be related to a chronic inflammatory state, at the level of specific cerebral areas which have been found as well impaired and responsible for schizophrenia symptomatology. Hence, a role of inflammatory mediators and cytokines has been as well defined. Accordingly, the role of an acute inflammatory phase protein, the C-reactive protein (CRP) has been recently investigated.

OBJECTIVE

The objective of the present study is to evaluate how PCR may represent a biomarker in schizophrenia, i.e. correlated with illness phases and/or clinical manifestation and/or psychopathological severity.

METHODS

A systematic review was here carried out by searching the following keywords ((C-reactive protein AND ((schizophrenia) OR (psychotic disorder))) for the topics 'PCR' and 'Schizophrenia', by using MESH terms.

RESULTS

An immune dysfunction and inflammation have been described amongst schizophrenic patients. Findings reported elevated CRP levels in schizophrenia, mainly correlated with the severity of illness and during the recrudescent phase. CRP levels are higher when catatonic features, negative symptomatology and aggressiveness are associated. CRP levels appeared not to be related to suicidal behaviour and ideation.

CONCLUSION

CRP and its blood levels have been reported higher amongst schizophrenic patients, by suggesting a role of inflammation in the pathogenesis of schizophrenia. Further studies are needed to better understand if CRP may be considered a biomarker in schizophrenia.

The relationship between salivary C-reactive protein and cognitive function in children aged 11-14years: Does psychopathology have a moderating effect?

Elevated C-reactive protein (CRP), a non-specific biomarker of systemic bodily inflammation, has been associated with more pronounced cognitive impairments in adults with psychiatric disorders, particularly in the domains of memory and executive function. Whether this association is present in early life (i.e., the time at which the cognitive impairments that characterise these disorders become evident), and is specific to those with emerging psychiatric disorders, has yet to be investigated. To this end, we examined the association between salivary CRP and cognitive function in children aged 11-14years and explored the moderating effect of psychopathology. The study utilised data from an established longitudinal investigation of children recruited from the community (N=107) that had purposively over-sampled individuals experiencing psychopathology (determined using questionnaires). CRP was measured in saliva samples and participants completed assessments of cognition (memory and executive function) and psychopathology (internalising and externalising symptoms and psychotic-like experiences). Linear regression models indicated that higher salivary CRP was associated with poorer letter fluency (β=-0.24, p=0.006) and scores on the inhibition (β=-0.28, p=0.004) and inhibition/switching (β=-0.36, p<0.001) subtests of the colour-word interference test, but not with performance on any of the memory tasks (working, visual, and verbal memory tasks). Results were largely unchanged after adjustment for psychopathology and no significant interactions between CRP and psychopathology were observed on any cognitive measure. Our findings provide preliminary evidence that elevated salivary CRP is associated with poorer cognitive function in early life, but that this association is not moderated by concurrent psychopathology. These findings have implications for early intervention strategies that attempt to ameliorate cognitive deficits associated with emerging psychiatric disorders. Further research is needed to determine whether salivary CRP levels can be used as a valid marker of peripheral inflammation among healthy adolescents.

Association between C-reactive protein and risk of schizophrenia: An updated meta-analysis

C-reactive protein (CRP) has been indicated to be associated with the pathogenesis of schizophrenia (SZ) and other psychiatric disorders. The aim of this study is to investigate whether peripheral blood CRP levels are associated with the risk of SZ. We searched literature from databases of Pubmed, Embase and the Cochrane Library from inception to November 1, 2016 for studies that reported serum or plasma CRP levels in patients with SZ and non-SZ controls. At least two reviewers decided on eligibility and extracted data from included studies. Random effects meta-analyses were performed using standardized mean difference (SMD) as the effect estimate of the differences in CRP levels between subjects with SZ and healthy controls. We identified 18 studies representing 1963 patients with SZ and 3683 non-SZ controls. Compared with non-schizophrenics, blood CRP levels were moderately increased in people with SZ (SMD 0.53, 95% CI 0.30 to 0.76) irrespective of study region, sample size of included studies, patient mean age, age of SZ onset and patient body mass index. Publication bias was not detected through Egger's linear regression test (P = 0.292). We noticed that patients in Asia or Africa (n = 6, SMD 0.73, 95% CI 0.26 to 1.21) and whose age less than 30 years (n = 5, SMD 0.76, 95% CI 0.07 to 1.58) had substantially higher CRP levels. Our study provides evidence that higher CRP levels are associated with increased risk of SZ, especially for young adult patients less than 30 years. Further large-scale studies are strongly warranted to further confirm this association.

Associations between sleep quality and inflammatory markers in patients with schizophrenia

Sleep disorder is a risk factor for several systemic inflammation-related diseases and there are extensive data showing that schizophrenia is associated with chronic low-grade systemic inflammation. This study investigated the associations between sleep quality and inflammatory markers in patients with schizophrenia, which has not been examined before. Sleep quality (total sleep time, sleep efficiency, sleep onset latency, total activity counts, wake after sleep onset, number of awakening, and average length of awakening) was measured using actigraphy in 199 schizophrenia inpatients. The state of inflammation was measured using blood concentration of white blood cells (WBC) and neutrophils, together with neutrophil-lymphocyte ratio (NLR), and platelet-lymphocyte ratio (PLR). The results showed that total sleep time was negatively associated with NLR and PLR, and sleep efficiency was negatively associated with neutrophil counts and NLR. Sleep onset latency, total activity counts, wake after sleep onset, and number of awakening were positively associated with WBC and neutrophil counts. The average length of awakening was positively associated with NLR and PLR. This is the first report to suggest that improving sleep quality may modulate the state of inflammation in patients with schizophrenia.

Chronic Peripheral Inflammation is Associated With Cognitive Impairment in Schizophrenia: Results From the Multicentric FACE-SZ Dataset

OBJECTIVES

Inflammation, measured by abnormal blood C-reactive protein (CRP) level, has been described in schizophrenia (SZ), being inconsistently related to impaired cognitive functions. The aim of the present study is to investigate cognitive impairment associated with abnormal CRP levels in a large multi-centric sample of community-dwelling SZ patients, using a comprehensive neuropsychological battery.

METHOD

Three hundred sixty-nine community-dwelling stable SZ subjects (76.2% men, mean age 32.7 y) were included and tested with a comprehensive battery of neuropsychological tests. Abnormal CRP level was defined as >3mg/L.

RESULTS

Multiple factor analysis revealed that abnormal CRP levels, found in 104 patients (28.2%), were associated with impaired General Intellectual Ability and Abstract Reasoning (aOR = 0.56, 95% CI 0.35-0.90, P = .014), independently of age, sex, education level, psychotic symptomatology, treatments, and addiction comorbidities. Abnormal CRP levels were also associated with the decline of all components of working memory (respectively effect size [ES] = 0.25, P = .033; ES = 0.27, P = .04; ES = 0.33, P = .006; and ES = 0.38, P = .004) and a wide range of other impaired cognitive functions, including memory (ES = 0.26, P = .026), learning abilities (ES = 0.28, P = .035), semantic memory (ES = 0.26, P = .026), mental flexibility (ES = 0.26, P = .044), visual attention (ES = 0.23, P = .004) and speed of processing (ES = 0.23, P = .043).

CONCLUSION

Our results suggest that abnormal CRP level is associated with cognitive impairment in SZ. Evaluating the effectiveness of neuroprotective anti-inflammatory strategies is needed in order to prevent cognitive impairment in SZ.

A significant causal association between C-reactive protein levels and schizophrenia

Many observational studies have shown elevated blood CRP levels in schizophrenia compared with controls, and one population-based prospective study has reported that elevated plasma CRP levels were associated with late- and very-late-onset schizophrenia. Furthermore, several clinical studies have reported the efficacy of anti-inflammatory drugs on the symptoms in patients with schizophrenia. However, whether elevated CRP levels are causally related to schizophrenia is not still established because of confounding factors and reverse causality. In the present study, we demonstrated that serum CRP levels were significantly higher in patients with schizophrenia than in the controls by conducting a case-control study and a meta-analysis of case-control studies between schizophrenia and serum CRP levels. Furthermore, we provided evidence for a causal association between elevated CRP levels and increased schizophrenia risk by conducting a Mendelian randomization analysis. Our findings suggest that elevated CRP itself may be a causal risk factor for schizophrenia.