Cerebrospinal fluid abnormalities in first- and multi-episode schizophrenia-spectrum disorders: impact of clinical and demographical variables

Immune Cell Alterations in Psychotic Disorders: A Comprehensive Systematic Review and Meta-Analysis

BACKGROUND

A comprehensive meta-analysis on the composition of circulating immune cells from both the myeloid and the lymphoid lines including specialized subsets in blood and cerebrospinal fluid (CSF) of patients with psychotic disorders compared with healthy control participants has been lacking.

METHODS

Multiple databases (PubMed, EMBASE, Cochrane Library, Web of Science, ClinicalTrials.gov, and PsycINFO) were searched for eligible studies up until October 18, 2022. All studies investigating circulating immune cells in the blood and CSF from patients with psychotic disorders (ICD-10: F20 and F22-29) compared with healthy control participants were included.

RESULTS

A total of 86 studies were included in the meta-analysis. In the blood, the following categories of immune cells were elevated: leukocyte count (31 studies, standardized mean difference [SMD] = 0.35; 95% CI, 0.24 to 0.46), granulocyte count (4 studies, SMD = 0.57; 95% CI, 0.12 to 1.01), neutrophil granulocyte count (21 studies, SMD = 0.32; 95% CI, 0.11 to 0.54), monocyte count (23 studies, SMD = 0.40; 95% CI, 0.23 to 0.56), and B lymphocyte count (10 studies, SMD = 0.26; 95% CI, 0.04 to 0.48). Additionally, the neutrophil/lymphocyte ratio (23 studies, SMD = 0.40; 95% CI, 0.19 to 0.60), the monocyte/lymphocyte ratio (9 studies, SMD = 0.31; 95% CI, 0.04 to 0.57), and the platelet/lymphocyte ratio (10 studies, SMD = 0.23; 95% CI, 0.03 to 0.43) were elevated. The CSF cell count showed a similar tendency but was not significantly elevated (3 studies, SMD = 0.14; 95% CI, -0.04 to 0.32).

CONCLUSIONS

The results indicate a broad activation of the immune system in psychotic disorders, with cells from both the myeloid and the lymphoid line being elevated. However, CSF analyses were lacking in most of the studies, and many studies were hampered by insufficient adjustment for confounding factors such as body mass index and smoking.

Association of symptom severity and cerebrospinal fluid alterations in recent onset psychosis in schizophrenia-spectrum disorders - An individual patient data meta-analysis

Neuroinflammation and blood-cerebrospinal fluid barrier (BCB) disruption could be key elements in schizophrenia-spectrum disorderś(SSDs) etiology and symptom modulation. We present the largest two-stage individual patient data (IPD) meta-analysis, investigating the association of BCB disruption and cerebrospinal fluid (CSF) alterations with symptom severity in first-episode psychosis (FEP) and recent onset psychotic disorder (ROP) individuals, with a focus on sex-related differences. Data was collected from PubMed and EMBASE databases. FEP, ROP and high-risk syndromes for psychosis IPD were included if routine basic CSF-diagnostics were reported. Risk of bias of the included studies was evaluated. Random-effects meta-analyses and mixed-effects linear regression models were employed to assess the impact of BCB alterations on symptom severity. Published (6 studies) and unpublished IPD from n = 531 individuals was included in the analyses. CSF was altered in 38.8 % of individuals. No significant differences in symptom severity were found between individuals with and without CSF alterations (SMD = -0.17, 95 %CI -0.55-0.22, p = 0.341). However, males with elevated CSF/serum albumin ratios or any CSF alteration had significantly higher positive symptom scores than those without alterations (SMD = 0.34, 95 %CI 0.05-0.64, p = 0.037 and SMD = 0.29, 95 %CI 0.17-0.41p = 0.005, respectively). Mixed-effects and simple regression models showed no association (p > 0.1) between CSF parameters and symptomatic outcomes. No interaction between sex and CSF parameters was found (p > 0.1). BCB disruption appears highly prevalent in early psychosis and could be involved in positive symptomś severity in males, indicating potential difficult-to-treat states. This work highlights the need for considering BCB breakdownand sex-related differences in SSDs clinical trials and treatment strategies.

Inflammatory cerebrospinal fluid markers in schizophrenia spectrum disorders: A systematic review and meta-analysis of 69 studies with 5710 participants

BACKGROUND

There is increasing evidence of immune dysregulation and neuroinflammation occurring in schizophrenia. The aim of this study is to combine studies on routine CSF parameters, as well as cytokines and inflammatory proteins, in individuals with schizophrenia spectrum disorders.

METHODS

CSF parameters were summated and inverse variance meta-analyses using a random effects model were performed comparing mean difference or odds ratios. Between study heterogeneity was assessed using the I2 statistic. Quality assessment and sensitivity analyses were performed.

RESULTS

There were 69 studies of 5710 participants, including 3180 individuals with schizophrenia spectrum disorders. Averaged CSF parameters were within normal limits, however, between 3.1 % and 23.5 % of individual cases with schizophrenia spectrum disorders had an abnormal CSF result: Protein (abnormal in 23.5 % cases), albumin (in 18.5 %), presence of oligoclonal bands (in 9.3 %), white blood cell count (in 3.6 %), and IgG levels (3.1 %). Meta-analysis of 55 studies with non-psychiatric controls demonstrated a significant increase in CSF total protein (MD: 3.50, CI: 0.12-6.87), albumin ratio (MD: 0.55, CI: 0.02-0.09), white cell count (MD: 0.25, CI: 0.05-0.46), IL-6 (SMD: 0.53, CI: 0.29 to 0.77) and IL-8 (SMD: 0.56, CI: 0.11 to 1.01). Sensitivity analysis did not alter findings.

CONCLUSION

Abnormal CSF parameters, cytokines and inflammatory proteins were found in a significant proportion of individuals with schizophrenia spectrum disorders. This may indicate alterations to blood brain barrier function and permeability, CSF flow dynamics or neuroinflammation. Further research is needed to explore these potential mechanisms.