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Infectious biomarkers in patients with primary mental disorders: a comprehensive systematic review and meta-analysis
Vardan Nersesjan1, Benjamin Noer Larsen2, Elisabeth Wreford Andersen2
1Copenhagen Research Center for Biological and Precision Psychiatry, Mental Health Center Copenhagen, Copenhagen University Hospital, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
Background:
Understanding the risk of infections and the role they play in the etiology of mental disorders can offer ways to optimize the care for patients suffering from mental illnesses. However, a comprehensive systematic review and meta-analysis on the prevalence of infectious biomarkers reaching positive thresholds and their corresponding titer-levels in patients with severe mental illness compared to controls has been lacking.
Method:
PubMed, Cochrane Library, Clinical Trials, PsychINFO and Embase were searched for eligible studies up until December 2023. All studies measuring the prevalence or the levels of infectious biomarkers in blood (n = 191), cerebrospinal fluid (CSF, n = 8) or brain samples (n = 13) in patients with primary mental disorders (ICD-10: F20-F98) compared to a control group were included. Bias assessment was performed using the Newcastle-Ottawa scale.
Results:
208 studies were included in the meta-analysis. Overall, an infection screening reaching threshold for a positive test was more common among individuals with mental disorders compared to healthy controls (OR = 1.97; 95% CI: 1.67-2.32, 98 studies), and specifically for neurotropic infections (OR = 1.84; 95% CI: 1.55-2.17, 75 studies). The increased occurrence of infections was observed specifically for schizophrenia (OR = 2.14; 95% CI: 1.71-2.70, 63 studies) and mood disorders (OR = 1.82; 95% CI: 1.45-2.30, 42 studies). Levels of infection biomarkers of immunoglobulins or infection-specific antibodies were higher in individuals with mental disorders compared to healthy controls (standard mean difference = 0.43; 95% CI: 0.25-0.60, 27 studies). Looking only at brain samples compared to controls, results were non-significant (OR = 1.31; 95% CI: 0.64-2.68, I2 = 60.8%, 7 studies) CONCLUSION: These results show increased odds and higher infection load in patients with mental disorders and cement this association across several disorders and microbiological agents. However, the included studies were cross-sectional only, and thus causality cannot be inferred. Moreover, all outcomes had substantial heterogeneity and wide prediction intervals. Future studies should focus on examining infectious biomarkers in CSF in patients with new-onset mental disorders and include data on symptom severity while routinely examining biomarkers in blood and exploring newer advanced methods of infection detection.
Insights
Infections are more common in individuals with severe mental illness compared to controls. This meta-analysis shows increased infection biomarkers in patients with schizophrenia and mood disorders.
Area of Science:
- Neuroscience
- Psychiatry
- Infectious Diseases
Background:
- Understanding the role of infections in mental disorders is crucial for optimizing patient care.
- A comprehensive review on infectious biomarkers in severe mental illness is lacking.
Purpose of the Study:
- To systematically review and meta-analyze the prevalence and levels of infectious biomarkers in patients with severe mental illness compared to controls.
- To investigate the association between infections and primary mental disorders (ICD-10: F20-F98).
Main Methods:
- Searched PubMed, Cochrane Library, Clinical Trials, PsychINFO, and Embase up to December 2023.
- Included 208 studies measuring infectious biomarkers in blood, cerebrospinal fluid (CSF), or brain samples.
- Assessed bias using the Newcastle-Ottawa scale.
Main Results:
- Infection screening was more common in individuals with mental disorders (OR=1.97).
- Neurotropic infections were significantly associated with mental disorders (OR=1.84).
- Elevated infection biomarkers (immunoglobulins, antibodies) were found in mental disorder patients (SMD=0.43).
Conclusions:
- Results indicate increased odds and higher infection load in patients with mental disorders, including schizophrenia and mood disorders.
- Causality cannot be inferred due to the cross-sectional nature of the studies.
- Future research should focus on CSF biomarkers in new-onset disorders and explore advanced detection methods.
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