Cytokines in agitated and non-agitated patients admitted to an acute psychiatric department: A cross-sectional study

Transdiagnostic Associations between Anger Hostility and Chemokine Interferon-gamma Inducible Protein 10

Objective

Many psychiatric disorders are linked to low grade systemic inflammation as measured by systemic cytokine levels. Exploration of cytokines and immune activity and their role in psychiatric symptoms may inform pathobiology and treatment opportunities. The aim of this study is to explore if there are associations between cytokines and psychiatric symptom clusters. Comparison between patients regularly using and those not using psychotropic medication is also conducted.

Methods

This was a cross sectional naturalistic study with 132 participants from a general open inpatient psychiatric ward at the Nordland Hospital Trust, Norway. Serum levels of 28 different cytokines were assessed. Psychiatric symptoms the last week were assessed by a self-rating scale (Symptom check list, SCL-90-R) and grouped in defined clusters. Multiple linear regression model was used for statistical analyses of associations between levels of cytokines and symptoms, adjusting for possible confounding factors.

Results

We found a positive association (p = 0.009) between the chemokine interferon-gamma inducible protein 10 (CXCL 10; IP-10) and the anger hostility cluster. No associations were found between the other symptom clusters and cytokines. IP-10 and the anger hostility cluster were positively associated (p = 0.002) in the subgroup of patients using psychotropic medication, not in the subgroup not using psychotropic medication.

Conclusion

Our analyses revealed a significant positive association between the symptom cluster anger hostility in SCL-90-R and the chemokine IP-10 in the subgroup of patients using psychotropic medications.

Impulsivity across severe mental disorders: a cross-sectional study of immune markers and psychopharmacotherapy

BACKGROUND

Impulsivity is a transdiagnostic feature linked to severe clinical expression and a potential target for psychopharmacological strategies. Biological underpinnings are largely unknown, but involvement of immune dysregulation has been indicated, and the effects of psychopharmacological agents vary. We investigated if impulsivity was associated with circulating immune marker levels and with a range of psychopharmacological treatment regimens in severe mental disorders.

METHODS

Impulsivity was assessed in a sample (N = 657) of patients with schizophrenia or schizophreniform disorder (SCZ) (N = 116) or bipolar disorder (BD) (N = 159) and healthy participants (N = 382) using the Barratt Impulsiveness Scale (BIS-11) questionnaire. Plasma levels of systemic immune markers (RANTES, IL-1RA, IL-18, IL-18BP, sTNFR-1) were measured by enzyme immunoassays. Patients underwent thorough clinical assessment, including evaluation of psychotropic medication. Associations were assessed using linear regressions.

RESULTS

Impulsivity  was positively associated with SCZ (p < 0.001) and BD (p < 0.001) diagnosis and negatively associated with age (p < 0.05), but not significantly associated with any of the circulating immune markers independently of diagnostic status. Among patients, impulsivity was negatively associated with lithium treatment (p = 0.003) and positively associated with antidepressant treatment (p = 0.011) after controlling for diagnosis, psychotropic co-medications, manic symptoms, and depressive symptoms.

CONCLUSIONS

We report elevated impulsivity across SCZ and BD but no associations to systemic immune dysregulation based on the current immune marker selection. The present study reveals associations between impulsivity in severe mental disorders and treatment with lithium and antidepressants, with opposite directions. Future studies are warranted to determine the causal directionality of the observed associations with psychopharmacotherapy.

Interleukin-18 signaling system links to agitation in severe mental disorders

OBJECTIVE

Agitation is a challenging clinical feature in severe mental disorders, but its biological correlates are largely unknown. Inflammasome-related abnormalities have been linked to severe mental disorders and implicated in animal models of agitation. We investigated if levels of circulating inflammasome-related immune markers were associated with agitation in severe mental disorders.

METHODS

Individuals with a psychotic or affective disorder (N = 660) underwent blood sampling and clinical characterization. Plasma levels of interleukin (IL)-18, IL-18 binding protein (IL-18BP), IL-18 receptor 1 (IL-18R1), IL-18 receptor accessory protein (IL-18RAP), and IL-1 receptor antagonist (IL-1RA) were measured. Agitation levels were estimated with the Positive and Negative Syndrome Scale Excited Component. Multiple linear- and logistic regression were used to investigate the associations between agitation and the immune markers, while controlling for confounders. The influence of psychotic and affective symptoms was assessed in follow-up analyses.

RESULTS

Agitation was positively associated with IL-18BP (β = 0.13, t = 3.41, p = 0.0007) after controlling for multiple confounders, including BMI, smoking, medication, and substance use. Adjustment for psychotic, manic, and depressive symptoms did not affect the results. There were no significant associations between agitation and the other investigated immune markers (IL-1RA (β = 0.06, t = 1.27, p = 0.20), IL-18 (β = 0.05, t = 1.25, p = 0.21), IL-18R1 (β = 0.04, t = 1.01, p = 0.31), IL-18RAP (odds ratio = 0.96, p = 0.30)). In a subsample (N = 463), we also adjusted for cortisol levels, which yielded unaltered results.

CONCLUSION

Our findings add to the accumulating evidence of immune system disturbances in severe mental disorders and suggest the IL-18 system as a part of the biological correlate of agitation independent of affective and psychotic symptoms.

Identifying strategies to improve PANSS based dimensional models in schizophrenia: Accounting for multilevel structure, Bayesian model and clinical staging

BACKGROUND

Dimensional approaches can decompose a construct in a set of continuous variables, improving the characterization of complex phenotypes, such as schizophrenia. However, the five-factor model of the Positive and Negative Syndrome Scale (PANSS), the most used instrument in schizophrenia research, yielded poor fits in most confirmatory factor analysis (CFA) studies, raising concerns about its applications. Thus, we aimed to identify dimensional PANSS CFA models with good psychometric properties by comparing the traditional CFA with three methodological approaches: Bayesian CFA, multilevel modeling, and Multiple Indicators Multiple Causes (MIMIC) modeling.

METHODS

Clinical data of 700 schizophrenia patients from four centers were analyzed. We first performed a traditional CFA. Next, we tested the three techniques: 1) a Bayesian CFA; 2) a multilevel analysis using the centers as level; and 3) a MIMIC modeling to evaluate the impact of clinical staging on PANSS factors and items.

RESULTS

CFA and Bayesian CFA produced poor fit models. However, when adding a multilevel structure to the CFA model, a good fit model emerged. MIMIC modeling yielded significant differences in the factor structure between the clinical stages of schizophrenia. Sex, age, age of onset, and duration of illness did not significantly affect the model fit.

CONCLUSION

Our comparison of different CFA methods highlights the need for multilevel structure to achieve a good fit model and the potential utility of staging models (rather than the duration of illness) to deal with clinical heterogeneity in schizophrenia. Large prospective samples with biological data should help to understand the interplay between psychometrics concerns and neurobiology research.

Association between brain-derived neurotropic factor (BDNF), high-sensitivity C-reactive protein (hs-CRP) and psychiatric symptoms in medicated and unmedicated patients

BACKGROUND

There is evidence that brain-derived neurotropic factor (BDNF) plays a protective role in the brain. Peripheral levels of BDNF correlate with its concentration in the brain. Previous studies have revealed lower serum BDNF levels in patients with mental illnesses. In most studies serum BDNF correlates negatively with psychiatric disorders and disease severity. Most studies in this field are on psychiatric diagnosis and personality traits. The aim of our study is to explore associations between general psychiatric symptoms, independent of diagnostic groups, and serum BDNF as well as the inflammatory biomarker high-sensitive CRP (hs-CRP). Comparison between the group regularly using psychotropic medication and those not using psychotropic medication is conducted.

METHODS

The study is a cross sectional study with 132 participants from a general open inpatient psychiatric ward at the Nordland Hospital Trust, Bodoe, Norway. Participants were assessed on serum levels of BDNF and hs-CRP. Psychiatric symptoms were assessed by a self-rating scale (Symptom check list, SCL-90- R). Multiple linear regression model was used for statistical analyses of associations between levels of BDNF, hs-CRP and symptoms.

RESULTS

We found a positive association (p < 0.05), for most SCL-90 symptom clusters with BDNF in the psychotropic medication-free group. No associations were found in the group of patients using psychotropic medication, except one, the paranoid ideation cluster (p 0.022). No associations were found between hs-CRP and symptom clusters.

CONCLUSION

We found no relation between symptom clusters and the inflammatory biomarker hs-CRP. Serum BDNF levels were positively associated with intensity of psychiatric symptoms in the group of patients not using psychotropic medication. Our findings are in conflict with several previous studies reporting increased hs-CRP as well as decreased rather than increased BDNF in mental suffering. Patients on psychotropic medication may not require the same upregulation because the medication is modulating the underlying biological pathology.