Chronic low-grade peripheral inflammation is associated with severe nicotine dependence in schizophrenia: results from the national multicentric FACE-SZ cohort

Could CRP be a differential biomarker of illness stages in schizophrenia? A systematic review and meta-analysis

BACKGROUND

Patients with schizophrenia display peripheral inflammation but the impact of illness phase is not clear. Our meta-analysis investigated the difference in CRP levels between patients with schizophrenia and controls according to their illness phase.

METHODS

After a systematic search, all studies measuring CRP in patients with schizophrenia and controls were included. Standardized mean differences were calculated between patients and controls according to illness phase. The influence of sociodemographic and clinical variables on our results was investigated using a meta-regression analysis.

RESULTS

Fifty studies were included in this meta-analysis. Patients with schizophrenia had higher CRP levels than controls in the acute (p < 0.00001) and stable (p < 0.00001) stage of their disease. Patients with acute exacerbation of schizophrenia had higher CRP levels than stable patients (p = 0.02) but this difference did not persist when considering antipsychotic-medicated patients in both phases. Meta-regressions found that the increase of CRP in acutely ill patients as compared to controls was influenced by age (p < 0.01), BMI (p = 0.01) and first episode (p = 0.02), whereas the increase in CRP levels of stable patients as compared to controls was moderated by BMI (p = 0.004).

CONCLUSIONS

In conclusion, this meta-analysis provides strong evidence that patients with schizophrenia have higher CRP levels than controls, but also show an increase in inflammatory response in the acute stage of the disease as compared to the stable stage. CRP could thus be considered as a state marker and a trait marker of the disease.

Redefining peripheral inflammation signature in schizophrenia based on the real-world FACE-SZ cohort

BACKGROUND

Peripheral inflammation is associated with impaired prognosis in schizophrenia (SZ). Highly sensitive C-reactive protein (hs-CRP) is the most used inflammatory biomarker in daily practice. However, no consensual cut-off has been determined to date to discriminate patients with peripheral inflammation from those without.

AIMS

To determine if patients with peripheral inflammation between 1 and 3 mg/L had poorer outcomes compared to those with undetectable CRP (<1 mg/L).

METHOD

Consecutive participants of the FACE-SZ cohort with a hs-CRP < 3 mg/L were included in 10 expert academic centers with a national geographical distribution between 2010 and 2018. Potential sources of inflammation, socio-demographics, illness characteristics, current illness severity, functioning and quality of life and were reported following the FACE-SZ standardized protocol.

RESULTS

580 patients were included, of whom 226 (39%) were identified with low-grade inflammation defined by a hs-CRP between 1 and 3 mg/L. Overweight and lack of dental care were identified as potential sources of inflammation. After adjustment for these factors, patients with inflammation had more severe psychotic, depressive and aggressive symptomatology and impaired functioning compared to the patients with undetectable hs-CRP. No association with tobacco smoking or physical activity level has been found.

CONCLUSIONS

Patients with schizophrenia with hs-CRP level between 1 and 3 mg/L should be considered at risk for inflammation-associated disorders. Lowering weight and increasing dental care may be useful strategies to limit the sources of peripheral inflammation. Hs-CRP > 1 mg/L is a reliable marker to detect peripheral inflammation in patients with schizophrenia.

Serum level of high sensitive C-reactive protein and IL - 6 markers in patients with treatment-resistant schizophrenia in Ethiopia: a comparative study

BACKGROUND

Accumulating evidence indicates that schizophrenia is accompanied by significant activation of the immune system; however, there is limited data from low and middle-income countries (LMIC). Inflammatory markers may be more relevant in LMIC settings where infectious conditions are more prevalent and may thus play some role in the causation and maintenance of schizophrenia. The aim of this study was to assess the level of inflammatory markers high sensitive C-reactive protein (hsCRP) and interleukin-6 (IL-6) in patients with schizophrenia.

MATERIALS AND METHODS

The study population consisted of a total of 132 study participants; 82 participants with schizophrenia and 50 controls. hsCRP and IL-6 were measured using Cobas Integra 400 Plus and Cobas e 411 analysers respectively.

RESULTS

The levels of hsCRP and IL-6 were significantly increased among participants with schizophrenia compared to controls: hsCRP mean value 2.87 ± 5.6 vs 0.67 ± 0.6 mg/L; IL-6 mean value 6.63 ± 5.6 vs 3.37 ± 4.0 pg/ml. Controlling for potential confounders (age, sex and body mass index), having a diagnosis of schizophrenia remained significantly associated with increased hsCRP and IL-6.

CONCLUSION

The results confirm that inflammatory processes may have a role in the pathophysiology of schizophrenia regardless of setting. Despite failure of some interventions with anti-inflammatory properties, interventions to reduce inflammation are still worth pursuing.

Depressive symptoms and chronic peripheral inflammation are associated with impaired functional remission in schizophrenia independently of psychotic remission

BACKGROUND

While psychotic remission in schizophrenia (SZ) has been defined by consensus and associated with a rank of clinical predictive factors, there is a lack of data of factors associated with functional remission.

OBJECTIVES

To identify clinical and biological factors associated with impaired functional remission in a non-selected chronic stabilized SZ outpatients.

METHODS

This study was a cross-sectional study carried out on all admitted SZ stabilized outpatients in an academic daily care psychiatric hospital. Functional remission was defined by a global assessment of functioning score ≥61. Psychotic remission was defined according to international criteria. Depression was assessed with the Calgary Depression Rating scale for Schizophrenia. Sociodemographic variables, tobacco status, clozapine treatment and obesity were reported. Chronic peripheral inflammation was defined by a highly sensitive C-reactive protein serum level ≥3 mg/L and metabolic syndrome according to international recommendations.

RESULTS

273 patients were included, among them 51 (18.7%) were classified in the functional remission group. In the multivariate analysis, higher rate of functional remission was associated with psychotic remission (adjusted Odd ratio = 18.2, p <0.001), lower depressive symptoms (aOR=0.8, p = 0.018) and lower peripheral inflammation (aOR=0.4, p = 0.046). No association of functional remission with age, gender, illness duration, second-generation antipsychotics, clozapine treatment, tobacco smoking, obesity or metabolic syndrome has been found.

CONCLUSION

Depressive symptoms and chronic peripheral inflammation are associated with impaired functional remission in SZ independently of psychotic remission. Future intervention studies should determine if improving depressive symptoms and chronic peripheral inflammation may improve SZ patients reaching functional remission.

Self-reported cannabis use and biomarkers of inflammation among adults in the United States

BACKGROUND

Cannabis is among the most frequently used substance in United States (U.S.). Studies evaluating the association between cannabis use and inflammation in humans have been few and have not explored potential sex-dependent effects.

OBJECTIVE

To examine the relationship between self-reported cannabis use and high-sensitivity C-reactive protein (hsCRP), Interleukin 6 (IL-6) and fibrinogen.

METHODS

We used Wave 1 of the Population Assessment of Tobacco and Health (PATH) - a nationally representative sample of adults in the U.S. Weighted linear regression models were used to determine associations of self-reported cannabis use with natural log-transformed hs-CRP, IL-6 and fibrinogen adjusting for sociodemographic and psychosocial factors.

RESULTS

Self-reported cannabis use, particularly cannabis use within the past 30 days, was associated with lower levels of each biomarker of systemic inflammation, although findings were imprecise. Specifically, in multivariable models, the associations between respondents who self-reported cannabis use in the past 30 days compared to never use was imprecise for hs-CRP (β= -0.15, 95% confidence interval (CI): -0.32, 0.00), IL-6 (β= - 0.02, 95% CI: -0.10, 0.05) and fibrinogen (β= - 0.01, 95% CI: -0.04, 0.02). We did not find that these associations differed significantly by sex.

DISCUSSIONS

Data from this nationally representative study suggest potential anti-inflammatory effects of recent cannabis use. Additional studies that biologically measure the THC and CBD concentrations of the cannabis used and employ prospective and or experimental study designs investigate cannabis and inflammation associations are needed.

One-day tropisetron treatment improves cognitive deficits and P50 inhibition deficits in schizophrenia

The core features of schizophrenia (SCZ) include cognitive deficits and impaired sensory gating represented by P50 inhibition deficits, which appear to be related to the α7 nicotinic acetylcholine receptor (nAChR). An agonist of nAChR receptor may improve these defects. This study aimed to investigate how administering multiple doses of tropisetron, a partial agonist of nAChR, for 1 day would affect cognitive deficits and P50 inhibition deficits in SCZ patients. We randomized 40 SCZ non-smokers into a double-blind clinical trial with four groups: placebo, 5 mg/d, 10 mg/d, and 20 mg/d of oral tropisetron. Their P50 ratios were all more than 0.5 and they took risperidone at 3-6 mg/day for at least a month before participating in the experiment. We measured the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and P50 inhibition before and one day after treatment. After one day of treatment, the total RBANS scores of the 20 mg and 5 mg tropisetron groups, and the immediate memory of the 10 mg group were significantly higher than placebo group. The P50 ratio was smaller in the 5 mg and 10 mg groups than in the placebo group (both p < 0.05) after treatment. Furthermore, the improvement in RBANS total score was correlated with increased S1 latency (p < 0.05), and the increase in immediate memory score was correlated with decreased S2 amplitude. One day of treatment with tropisetron improved both cognitive and P50 inhibition deficits, suggesting that longer term treatment with α7 nAChR agonists for these deficits in SCZ may be promising.

Microbiota-Orientated Treatments for Major Depression and Schizophrenia

Background and significance. There is a need to develop new hypothesis-driven treatment for both both major depression (MD) and schizophrenia in which the risk of depression is 5 times higher than the general population. Major depression has been also associated with poor illness outcomes including pain, metabolic disturbances, and less adherence. Conventional antidepressants are partly effective, and 44% of the subjects remain unremitted under treatment. Improving MD treatment efficacy is thus needed to improve the SZ prognosis. Microbiota-orientated treatments are currently one of the most promising tracks. Method. This work is a systematic review synthetizing data of arguments to develop microbiota-orientated treatments (including fecal microbiota transplantation (FMT)) in major depression and schizophrenia. Results. The effectiveness of probiotic administration in MD constitutes a strong evidence for developing microbiota-orientated treatments. Probiotics have yielded medium-to-large significant effects on depressive symptoms, but it is still unclear if the effect is maintained following probiotic discontinuation. Several factors may limit MD improvement when using probiotics, including the small number of bacterial strains administered in probiotic complementary agents, as well as the presence of a disturbed gut microbiota that probably limits the probiotics’ impact. FMT is a safe technique enabling to improve microbiota in several gut disorders. The benefit/risk ratio of FMT has been discussed and has been recently improved by capsule administration. Conclusion. Cleaning up the gut microbiota by transplanting a totally new human gut microbiota in one shot, which is referred to as FMT, is likely to strongly improve the efficacy of microbiota-orientated treatments in MD and schizophrenia and maintain the effect over time. This hypothesis should be tested in future clinical trials.

Abnormal C-reactive protein blood levels as a specific biomarker of major depression and non-remission under antidepressants in schizophrenia

BACKGROUND

C-reactive protein (CRP) is a general marker of peripheral inflammation and has been shown to be a good marker of neuroinflammation. CRP has been found to be elevated in patients with mood disorders (especially unipolar disorders (UD) and in schizophrenia (SZ)) but also to be lowered by antidepressants.

OBJECTIVE

The objectives were (i) to determine the prevalence of major depression, antidepressant prescription and remission under antidepressant in a stabilized population of SZ and UD patients consulting in a daily hospital, and (ii) to determine if CRP was a marker of major depression and remission under antidepressant in these SZ and UD populations.

METHODS

Abnormal CRP was defined by a CRP blood level ≥ 3 mg/L. Depressive symptoms were assessed by the Calgary Depression Rating Scale score. The clinicians were blinded of the CRP status of the patient.

RESULTS

411 patients were included (272 SZ and 139 UD). 171 (41.6%) were diagnosed with current major depression (74 (27.2%) for SZ and 97 (69.8%) for UD). 86 SZ (31.6%) and 119 UD (85.6%) were treated by antidepressant. Only 28/74 (37.8%) of the SZ subjects with major depression were administered antidepressants vs. 87/97 (89.7%) for UD. The non-remission rate under antidepressant was 28/86(32.6%) for SZ and 87/119 (73.1%) for UD. Overall, 105 (40.1%) of SZ and 39 (28.1%) of UD patients were found to have abnormal CRP blood levels. Abnormal CRP levels were significantly associated with increased MDD and more strongly with increased rates of non-remission under antidepressants in SZ patients, independently of age, gender, psychotic symptomatology, functioning, tobacco smoking and metabolic syndrome. This result was not replicated in UD patients, which suggests that CRP may be a specific marker of major depression and remission under antidepressant in SZ patients.

CONCLUSION

The development of biomarkers in psychiatry may orientate specific etiologic therapies in patients with mental disorders. The present findings suggest that major depression is frequent in SZ patients and that increased CRP levels are associated with non-remission under antidepressants in this population. Anti-inflammatory strategies may be particularly useful in this specific population.

The Role of Inflammation in the Treatment of Schizophrenia

Background: Inflammation plays a major role in the onset and maintenance of schizophrenia. The objective of the present work was to synthetize in a narrative review the recent findings in the field of inflammation in schizophrenia and their application in daily practice. Method: This review was based on the most recent meta-analyses and randomized controlled trials. Results: The disturbed cytokines depend on the phase of the illness. A meta-analysis of cytokines in schizophrenia found higher levels of pro-inflammatory and anti-inflammatory cytokines in the peripheral blood in both patients with first-episode schizophrenia and relapsed patients than in healthy controls. Exploring detailed data on immune-inflammatory disturbances in SZ reveals that IL-6 is one of the most consistently disturbed cytokines. Other cytokines, including IL1, TNF, and IFN, are also disturbed in schizophrenia. Choosing a broad spectrum anti-inflammatory agent that may inhibit subsequent pathways might be particularly useful for the treatment of inflammatory schizophrenia. Highly sensitive C-Reactive Protein is a useful screening marker for detecting inflammation in SZ subjects. Anti-inflammatory agents have shown effectiveness in recently published meta-analyses. Only one study found a significant difference between celecoxib and placebo, but two found a trend toward significance on illness severity and one on positive symptoms. In addition, other published and unpublished data were included in another meta-analysis that concluded the significant effect of add-on celecoxib in positive symptoms in first episode patients. There is a lack of data to determine if aspirin is truly effective in schizophrenia to date. Other anti-inflammatory agents have been explored, including hormonal therapies, antioxidants, omega 3 fatty acids, and minocycline, showing significant effects for reducing total, positive, and negative score symptoms and general functioning. However, each of these agents has multiple properties beyond inflammation and it remains unclear how these drugs improve schizophrenia. Conclusion: The next step is to tailor anti-inflammatory therapy in schizophrenia, with two main challenges: 1. To provide a more efficient anti-inflammatory therapeutic approach that targets specific pathways associated with the pathology of schizophrenia. 2. To develop a more personalized approach in targeting patients who have the best chance of successful treatment.

Inflammatory DEpression Advances in Schizophrenia (IDEAS): A precision medicine approach of the national FACE-SZ cohort

BACKGROUND

Major Depressive Disorder (MDD) is a therapeutic challenge in schizophrenia (SZ). Untangling different forms of MDD appears as the best current strategy to improve remission to treatment in the so-called precision medicine approach.

AIMS

The objectives of the present study were to determine (i) the prevalence of Inflammatory Depression (ID) in stabilized SZ outpatients (ii) if ID was associated with clinical or cognitive profiles that may help clinicians detecting ID (iii) if antidepressants were effective in ID and (iv) the biological correlates of ID that may orientate personalized treatments.

METHOD

Participants were consecutively included and received a thorough 2 days- clinical assessment.

RESULTS

785 subjects were recruited in the FACE-SZ cohort. 289 (36.8%) were diagnosed with MDD (remitted or unremitted), of them 57 with ID (19.7%). No clinical or cognitive features were associated with ID (all p > 0.05). ID has been associated with increased abdominal perimeter (aOR = 4.48, p = 0.002) and latent Toxoplasma infection (aOR = 2.19, p = 0.04). While antidepressants were associated with decreased depressive symptoms level in ID, 44% of the subjects remained unremitted under antidepressant, with no association with CRP blood levels.

CONCLUSIONS

ID may not differ from other forms of depression by its clinical symptoms but by its aetiologies. ID is associated with increased perivisceral fat and latent Toxoplasma infection that are both potentially related to gut/microbiota disturbances. Specific anti-inflammatory drugs and microbiota-targeted therapeutics appear as promising strategies in the treatment of inflammatory depression in schizophrenia.

Metabolic-inflammatory status as predictor of clinical outcome at 1-year follow-up in patients with first episode psychosis

BACKGROUND

Metabolic abnormalities and peripheral inflammation have been increasingly reported in patients at the onset of psychosis and associated with important physical health disorders and increased mortality. However, the impact of an abnormal metabolic-inflammatory status on the psychiatric outcome of these patients has not yet been investigated.

OBJECTIVES

The aims of this study were 1) to explore whether, in a sample of patients at their first episode of psychosis (FEP), an overall metabolic-inflammatory status may be measured, by combining metabolic and inflammatory variables in metabolic-inflammatory factors; 2) to explore the association between these factors and clinical outcome at 1-year follow-up (FU), in terms of symptoms severity and treatment response.

METHODS

In this longitudinal study we recruited 42 FEP patients and 46 healthy controls (HC) matched with patients for age, gender and ethnicity. At baseline (T1) we measured high sensitivity C-reactive protein (hsCRP) as biomarker of inflammation, and body mass index (BMI), lipid profile and gluco-metabolic parameters (glycated hemoglobin (HbA1c) and fasting glucose) as metabolic variables. A principal component analysis (PCA) was then used to reduce the dimensionality of the dataset accounting for both inflammation and metabolic status. In FEP patients, we assessed symptoms severity at T1 and at 1-year FU (T2) as well as treatment response to antipsychotics at T2.

RESULTS

at T1, FEP showed higher HbA1c (p = 0.034), triglycerides (TG) (p = 0.045) and BMI (p = 0.026) than HC. PCA identified 3 factors: factor 1 accounting for hsCRP, TG and BMI, factor 2 accounting for LDL and cholesterol, and factor 3 accounting for fasting glucose and HbA1c. Factor 1 was associated with T1 negative symptoms severity (p = 0.021) and predicted T2 positive (p = 0.004) and overall symptoms severity (0.001), as well as general psychopathology (p < 0.001) and T2 treatment response (p = 0.007).

CONCLUSION

In this sample of FEP patients, inflammation and metabolism, closely correlated at the onset of psychosis, proved to play a key role as predictors of the clinical course of psychosis when combined in a single factor. These findings offer an important potential target for early screening and interventions.

Influence of Venus and Mars in the cognitive sky of schizophrenia. Results from the first-step national FACE-SZ cohort

OBJECTIVES

Sex differences can yield important clues regarding illness pathophysiology and its treatment. Schizophrenia (SZ) has a lower incidence rate, and a better prognosis, in women versus men. The present study investigated the cognitive profiles of both sexes in a large multi-centre sample of community-dwelling SZ patients.

METHOD

544 community-dwelling stable SZ subjects (141 women and 403 men; mean age 34.5±12.1 and 31.6±8.7years, respectively) were tested with a comprehensive battery of neuropsychological tests.

RESULTS

Although community-dwelling SZ men had more risk factors for impaired cognition (including first-generation antipsychotics administration and comorbid addictive disorders), women had lower scores on a wide range of cognitive functions, including current and premorbid intellectual functioning, working memory, semantic memory, non-verbal abstract thinking and aspects of visual exploration. However, women scored higher in tests of processing speed and verbal learning, as well as having a lower verbal learning bias. No sex difference were evident for visuospatial learning abilities, cued verbal recall, sustained attention and tests of executive functions, including cognitive flexibility, verbal abstract thinking, verbal fluency and planning abilities.

CONCLUSION

Sex differences are evident in the cognitive profiles of SZ patients. The impact on daily functioning and prognosis, as well as longitudinal trajectory, should be further investigated in the FACE-SZ follow-up study. Sex differences in cognition have implications for precision-medicine determined therapeutic strategies.

LIMITS

Given the restricted age range of the sample, future research will have to determine cognitive profiles across gender in late onset SZ.

Additive Effect of Cigarette Smoking on Gray Matter Abnormalities in Schizophrenia

It is widely known that there is a high prevalence of cigarette smoking in schizophrenia. One of the explanations is the self-medication hypothesis. Based on this hypothesis, it has been suggested that nicotine has procognitive effect or even neuroprotective effect in schizophrenia. However, cigarettes contain numerous neurotoxic substances, making the net effect of cigarette smoking on brain function and structure complex. Indeed, recent studies have called into question the self-medication hypothesis. We aimed to test whether there is an interaction between diagnosis and smoking status in gray matter volume, ie, whether smoking has specific effects on gray matter or whether main effects of these 2 variables additively affect common brain regions. Magnetic resonance imaging (MRI) images were obtained from 4 groups: (1) normal controls with no smoking history, (2) normal controls currently smoking and/or with a past history of smoking, (3) schizophrenia patients with no smoking history, and (4) schizophrenia patients currently smoking and/or with a past history of smoking. We used voxel-based morphometry to compare gray matter volumes among the 4 groups. We did not find any interaction between diagnosis and smoking, but we did find negative additive effects of schizophrenia diagnosis and smoking status in the left prefrontal cortex. The decrease in left prefrontal volume was associated with greater numbers of cigarette pack years and severe positive and negative symptoms. The current findings do not support the neuroprotective effect of smoking on gross brain structure in schizophrenia, emphasizing the necessity of longitudinal studies to test causal relationships among these variables.

Nicotine dependence in Croatian male inpatients with schizophrenia

BACKGROUND

Patients with schizophrenia have the highest known rates of cigarette smoking, but less is known about their smoking behavior and the differences across geographical regions, including Croatia. The aim of this study was to compare patterns of nicotine dependence between patients with schizophrenia and healthy individuals, and to determine the relationship between clinical presentation and the severity of smoking.

METHODS

This cross-sectional study included 182 recently hospitalized male inpatients and 280 healthy males, who were daily smokers. All participants have fulfilled the Fagerstrom Test for Nicotine Dependence (FTND). Patients were also evaluated by the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Patients had higher FTND total score (p = 0.010), smoked their first cigarette earlier in the morning (p = 0.000), consumed higher number of cigarettes (p = 0.000), while healthy subjects had more difficulties to refrain from smoking in places where it is forbidden (p = 0.000) and smoked more even when they were sick (p = 0.000). While severe dependence was more prevalent in the patient group, light dependence was more frequent in control subjects (p = 0.04). Smoking behavior was not associated with either PANSS total score or any of its subscales and items.

CONCLUSIONS

Smokers with schizophrenia differ from healthy smokers in both smoking behavior and level of dependence. Longitudinal studies are needed to shed more light on the complex relationship between smoking and psychopathology in schizophrenia.

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.