# Evaluating Microglial Dysfunction and Psychiatric Illness by Exploring the Inflammatory Basis of Schizophrenia and Depression in Cross-Sectional Study settings

## TL;DR

This study found that higher levels of certain inflammatory markers in the blood are linked to more severe symptoms in schizophrenia and depression.

## Contribution

The study provides empirical evidence linking peripheral cytokine levels to symptom severity in schizophrenia and depression.

## Key findings

- TNF-α, IL-6, and IL-1β levels were significantly higher in psychiatric patients compared to controls.
- Schizophrenia symptom severity correlated with IL-6 and TNF-α levels, while depression correlated with IL-6 and IL-1β.

## Abstract

Background: Growing evidence in research demonstrates that neuroinflammation plays an important role in the pathophysiology of schizophrenia and major depressive disorder. This study evaluated how peripheral inflammatory cytokines relate to the intensity of the psychiatric symptoms of these disorders.

Methods: A cross-sectional study was conducted that included 100 participants, of which 30 were schizophrenia patients, 30 were major depressive disorder (MDD) patients, and 40 were healthy controls. The inflammatory markers, also known as peripheral cytokines IL-6, TNF-α, and IL-1β, were measured using an ELISA method. The Positive and Negative Syndrome Scale (PANSS) and the Hamilton Depression Rating Scale (HAM-D) tools were used to evaluate symptom severity. To perform group comparisons, ANOVA was used, and for correlations, Pearson’s method was used.

Results: TNF-α and the cytokines IL-6 and IL-1β were found to be higher in patients than in control groups (p < 0.001), where the highest levels were observed in schizophrenia patients. PANSS scores in schizophrenia patients correlated with IL-6 and TNF-α serum levels, whereas MDD patients showed correlations between IL-6 and IL-1β levels and HAM-D scores.

Conclusion: Peripheral inflammatory markers were seen to be associated with psychiatric symptom severity, which supported the inflammatory hypothesis of mental illness. These cytokines might serve as accessible biomarkers. However, direct microglial assessment and longitudinal studies were needed for confirmation of results.