Retinal abnormalities associated with schizophrenia and bipolar disorder: a meta-analysis
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Abstract
INTRODUCTION: Schizophrenia (SZ) and bipolar disorder (BD) are neurodegenerative psychiatric disorders characterized by psychosis, cognitive impairment, and grey- and white-matter reductions in the brain. Non-invasive optical coherence tomography (OCT) has been increasingly utilized to investigate retinal abnormalities and their connections with underlying pathophysiology of psychiatric disorders. This thesis is a meta-analysis of current literature examining differences in retinal cytoarchitecture measured with OCT in patients with psychosis compared to controls.
METHODS: In this meta-analysis, 38 articles were identified using PubMed and Google Scholar. Diagnostic groups were SZ only, BD only, psychosis spectrum disorder (PSD) only, psychosis proband (SZ, BD, and PSD combined), and healthy control (HC) eyes. Meta-analyses utilized fixed and random effects models when appropriate, and publication bias was identified and corrected for using trim-and-fill analysis. Meta-analyses and meta-regressions were with the ‘meta’ package in R (version 4.1.1). Results were reported as standardized mean differences (SMD) with 95% confidence intervals.
RESULTS: A total of 3065 patient eyes (1664 SZ, 1189 BD, 212 PSD) and 3053 HC eyes were included in this meta-analysis. Compared to HCs, significant reductions were found in overall peripapillary RNFL thickness in BD and macular total retinal and mGCC thicknesses in proband, SZ, and BD groups. Overall, temporal, and inferior pRNFL thickness was significantly lower than controls in all patient groups except SZ, while superior and nasal pRNFL thickness was significantly lower than controls in proband and BD groups. Smaller significant reductions were also found in MV (except BD), mGCL-IPL volume, mGCL-IPL thickness (except BD), and foveal thickness (probands and PSD only). Finally, significant increases were seen in mOPL thickness (probands and PSD) and mINL volume (BD only).
CONCLUSION: This meta-analysis builds upon previous literature in this field by incorporating recent OCT studies and examining both peripapillary and macular retinal regions with respect to psychotic disorders. Overall, this meta-analysis demonstrated both peripapillary and macular structural retinal abnormalities in people with psychosis compared to healthy controls. Specifically, the pRNFL, mGCC, and macular total retina thicknesses were widely shown to be decreased in association with psychosis.