Optical coherence tomography reveals retinal thinning in schizophrenia spectrum disorders

Optical coherence tomography in patients with schizophrenia: An exploratory study

BACKGROUND

Neurodegeneration plays an important role in the pathophysiology of schizophrenia. Conventional imaging has limited sensitivity in identifying early degenerative changes in the brain. Optical Coherence Tomography (OCT) is a noninvasive method for assessing retinal changes, providing a window into the central nervous system.

METHODOLOGY

Thirty-six schizophrenia patients and 31 healthy controls aged 18-45 were included. OCT was used to measure macular thickness and volume across nine retinal regions. Comparative analyses were conducted using t-tests, and the association between retinal changes and clinical characteristics was explored.

RESULTS

Patients exhibited increased macular thickness in the central subfield (right: p = 0.006; left p = 0.009) and outer superior quadrant (left p < 0.001). Significant thinning was observed in the right outer temporal(p < 0.001) and right inner temporal(p = 0.024), left inner inferior(p = 0.013) and left outer nasal quadrants (p ≤ 0.001). Macular volume was lower in the patients but not statistically significant.

CONCLUSIONS

Schizophrenia can present with a mixed pattern of changes in the structure of the macula. This pattern could suggest inflammatory changes in the macular structures. Future studies need to focus on the etiopathogenesis of these inflammatory changes, which will help in a better understanding of schizophrenia.

Genetic susceptibility to schizophrenia through neuroinflammatory pathways associated with retinal thinness

Schizophrenia is associated with structural and functional changes in the central nervous system, including the most distal part of it, the retina. However, the question of whether retinal atrophy is present before individuals develop schizophrenia or is a secondary consequence of the disorder remains unanswered. Here we address this question by examining the association between polygenic risk scores for schizophrenia and retinal morphologies in individuals without a schizophrenia diagnosis. We used population data for 34,939 white British and Irish individuals from the UK Biobank. Our robust regression results show that higher polygenic risk scores for schizophrenia were associated with thinner overall maculae, while controlling for confounding factors (b = -0.17, P = 0.018). Similarly, we found that greater polygenic risk scores for schizophrenia specific to neuroinflammation gene sets were associated with thinner ganglion cell inner plexiform layers (b = -0.10, self-contained P = 0.014, competitive P = 0.02). These results provide new evidence for genetic factors that could predispose individuals to heightened neuroinflammatory responses. Over time, these responses could contribute to neurodegenerative processes such as retinal thinning.

Thinning of central foveal thickness in the retina of patients with schizophrenia

The neural retina shares a common embryonic origin with the brain and yields pathological changes like that in the brain in various neuropsychiatric disorders, including schizophrenia. Non-invasive examination by optical coherence tomography (OCT) revealed retinal structure abnormalities in patients with schizophrenia. This study investigated retina structures in 29 patients with schizophrenia and 25 healthy controls in a Chinese Han ethnic population with spectral domain OCT. Measurements of central foveal thickness (CFT) as well as other retinal structures in macular and peripapillary subregions were performed. Associations between OCT parameters and clinical features, including severity of positive and negative symptoms, disease duration and antipsychotic dosage were analyzed. With controlling for age and sex, patients showed significantly thinner CFT, thinner central macular thickness, and thinner total retinal thickness in subregions of the central, inner superior, inner temporal, and inner nasal macula of both eyes, thinner ganglion cell complex in a subregion of the left eye, as well as larger cup volume in the peripapillary region of the right eye. In addition, CFT also negatively correlated with severity of negative symptoms. These findings suggest that CFT has the potential to be a disease biomarker of schizophrenia.

Retinal Structure and Microcirculation Alterations in Patients With Papillary Thyroid Carcinoma: An Optical Coherence Tomography and Angiography Study

Purpose

This study aimed to compare the retinal thickness, vessel density, and perfusion density in patients with papillary thyroid carcinoma (PTC) and healthy controls using optical coherence tomography (OCT) and OCT angiography. And investigating the influence of serological parameters and carcinoma signs with retinal structural and microcirculatory in PTC patients.

Methods

This cross-sectional study included 174 PTC patients (345 eyes) and 179 healthy subjects (358 eyes). Serological parameters (complete blood count, thyroid function, and lymphocyte subsets) and retinal thickness and flow parameters were compared between the two groups, and the correlations of retinal parameters with serological parameters in the PTC group. We investigated the effect of carcinoma signs (tumor size, focus location, lymphatic metastasis, surrounding tissue invasion, and BRAF mutations) on retinal parameters.

Results

PTC patients exhibited significantly thinner retinal thickness and reduced vessel density and perfusion density in the macular superficial vascular plexus compared with healthy controls. Platelet-to-lymphocyte ratios and thyroglobulin were inversely correlated with retinal parameters, and CD4+ T cells were positively correlated. Aggressive carcinoma signs thicken the retinal thickness more than nonaggressive cases.

Conclusions

The findings indicate a trend toward macular thinning and retinal microcirculatory dysfunction in the PTC patients, and these changes may be related to chronic inflammation and immune dysregulation secondary to cancer progression. OCT and OCT angiography show potential as noninvasive tools for detecting subclinical retinal abnormalities in PTC patients, and retinal alterations may serve as a surrogate marker for systemic inflammation. However, further studies are needed to address confounders and establish causality.

Genetic Analysis of Retinal Cell Types in Neuropsychiatric Disorders

Importance

As an accessible part of the central nervous system, the retina provides a unique window to study pathophysiological mechanisms of brain disorders in humans. Imaging and electrophysiological studies have revealed retinal alterations across several neuropsychiatric and neurological disorders, but it remains largely unclear which specific cell types and biological mechanisms are involved.

Objective

To determine whether specific retinal cell types are affected by genomic risk for neuropsychiatric and neurological disorders and to explore the mechanisms through which genomic risk converges in these cell types.

Design, Setting, and Participants

This genetic association study combined findings from genome-wide association studies in schizophrenia, bipolar disorder, major depressive disorder, multiple sclerosis, Parkinson disease, Alzheimer disease, and stroke with retinal single-cell transcriptomic datasets from humans, macaques, and mice. To identify susceptible cell types, Multi-Marker Analysis of Genomic Annotation (MAGMA) cell-type enrichment analyses were applied and subsequent pathway analyses performed. The cellular top hits were translated to the structural level using retinal optical coherence tomography (acquired between 2009 and 2010) and genotyping data in the large population-based UK Biobank cohort study. Data analysis was conducted between 2022 and 2024.

Main Outcomes and Measures

Cell type-specific enrichment of genetic risk loading for neuropsychiatric and neurological disorder traits in the gene expression profiles of retinal cells.

Results

Expression profiles of amacrine cells (interneurons within the retina) were robustly enriched in schizophrenia genetic risk across mammalian species and in different developmental stages. This enrichment was primarily driven by genes involved in synapse biology. Moreover, expression profiles of retinal immune cell populations were enriched in multiple sclerosis genetic risk. No consistent cell-type associations were found for bipolar disorder, major depressive disorder, Parkinson disease, Alzheimer disease, or stroke. On the structural level, higher polygenic risk for schizophrenia was associated with thinning of the ganglion cell inner plexiform layer, which contains dendrites and synaptic connections of amacrine cells (B, -0.09; 95% CI, -0.16 to -0.03; P = .007; n = 36 349; mean [SD] age, 57.50 [8.00] years; 19 859 female [54.63%]). Higher polygenic risk for multiple sclerosis was associated with increased thickness of the retinal nerve fiber layer (B, 0.06; 95% CI, 0.02 to 0.10; P = .007; n = 36 371; mean [SD] age, 57.51 [8.00] years; 19 843 female [54.56%]).

Conclusions and Relevance

This study provides novel insights into the cellular underpinnings of retinal alterations in neuropsychiatric and neurological disorders and highlights the retina as a potential proxy to study synaptic pathology in schizophrenia.

On the improvement of schizophrenia detection with optical coherence tomography data using deep neural networks and aggregation functions

Schizophrenia is a serious mental disorder with a complex neurobiological background and a well-defined psychopathological picture. Despite many efforts, a definitive disease biomarker has still not been identified. One of the promising candidates for a disease-related biomarker could involve retinal morphology , given that the retina is a part of the central nervous system that is known to be affected in schizophrenia and related to multiple illness features. In this study Optical Coherence Tomography (OCT) data is applied to assess the different layers of the retina. OCT data were applied in the process of automatic differentiation of schizophrenic patients from healthy controls. Numerical experiments involved applying several individual 1D Convolutional Neural Network-based models as well as further using the aggregation of classification results to improve the initial classification results. The main goal of the study was to check how methods based on the aggregation of classification results work in classifying neuroanatomical features of schizophrenia. Among over 300, 000 different variants of tested aggregation operators, a few versions provided satisfactory results.

Retinal Optical Coherence Tomography in Bipolar Disorder: A Scoping Review

BACKGROUND

Bipolar disorder (BD) is a psychiatric condition with significant health implications due to its comorbidities, premature mortality, and functional impairments. Despite extensive research on treatment and rehabilitation, gaps remain in diagnosis and monitoring. Therefore, there is a need for biomarkers to identify individuals at risk for disease progression or exacerbation. Developmentally part of the central nervous system, the retina represents a possible marker for observing BD-related structural and functional alterations in the brain.

SUMMARY

The retina's structure can be assessed through optical coherence tomography (OCT), a noninvasive and cost-effective method. Retinal alterations, particularly in the retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), have been associated with neurodegenerative and psychiatric disorders in cross-sectional OCT studies. This scoping review discusses findings on retinal changes in BD as well as their association with disease characteristics like symptom severity and illness duration and highlights OCT as a potential diagnostic tool in BD treatment.

KEY FINDINGS

The majority of studies indicate RNFL and GCL thinning in BD patients, which was found to correlate with clinical characteristics in some studies. Although the data are currently limited, there is a possibility that retinal biomarkers could facilitate monitoring of BD, but more research needs to be conducted to observe the relationship between these parameters and BD. Moreover, other factors (e.g., treatment, metabolic and inflammatory conditions) may impact retinal changes, which highlights the need for longitudinal studies to clarify these relationships. Further research should focus on replicating current findings, understanding the role of inflammation, and differentiating between retinal regions affected by BD.

BACKGROUND

Bipolar disorder (BD) is a psychiatric condition with significant health implications due to its comorbidities, premature mortality, and functional impairments. Despite extensive research on treatment and rehabilitation, gaps remain in diagnosis and monitoring. Therefore, there is a need for biomarkers to identify individuals at risk for disease progression or exacerbation. Developmentally part of the central nervous system, the retina represents a possible marker for observing BD-related structural and functional alterations in the brain.

SUMMARY

The retina's structure can be assessed through optical coherence tomography (OCT), a noninvasive and cost-effective method. Retinal alterations, particularly in the retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), have been associated with neurodegenerative and psychiatric disorders in cross-sectional OCT studies. This scoping review discusses findings on retinal changes in BD as well as their association with disease characteristics like symptom severity and illness duration and highlights OCT as a potential diagnostic tool in BD treatment.

KEY FINDINGS

The majority of studies indicate RNFL and GCL thinning in BD patients, which was found to correlate with clinical characteristics in some studies. Although the data are currently limited, there is a possibility that retinal biomarkers could facilitate monitoring of BD, but more research needs to be conducted to observe the relationship between these parameters and BD. Moreover, other factors (e.g., treatment, metabolic and inflammatory conditions) may impact retinal changes, which highlights the need for longitudinal studies to clarify these relationships. Further research should focus on replicating current findings, understanding the role of inflammation, and differentiating between retinal regions affected by BD.

Investigation of choroid plexus variability in schizophrenia-spectrum disorders-insights from a multimodal study

Previous studies have suggested that choroid plexus (ChP) enlargement occurs in individuals with schizophrenia-spectrum disorders (SSD) and is associated with peripheral inflammation. However, it is unclear whether such an enlargement delineates a biologically defined subgroup of SSD. Moreover, it remains elusive how ChP is linked to brain regions associated with peripheral inflammation in SSD. A cross-sectional cohort of 132 individuals with SSD and 107 age-matched healthy controls (HC) underwent cerebral magnetic resonance imaging (MRI) and clinical phenotyping to investigate the ChP and associated regions. A case-control comparison of ChP volumes was conducted, and structural variance was analyzed by employing the variability ratio (VR). K-means clustering analysis was used to identify subgroups with distinct patterns of the ventricular system, and the clusters were compared in terms of demographic, clinical, and immunological measures. The relationship between ChP volumes and brain regions, previously associated with peripheral inflammation, was investigated. We did not find a significant enlargement of the ChP in SSD compared to HC but detected an increased VR of ChP and lateral ventricle volumes. Based on these regions, we identified 3 clusters with differences in cognitive measures and possibly inflammatory markers. Larger ChP volume was associated with higher volumes of hippocampus, putamen, and thalamus in SSD but not in HC. This study suggests that ChP variability, but not mean volume, is increased in individuals with SSD, compared to HC. Larger ChP volumes in SSD were associated with higher volumes of regions previously associated with peripheral inflammation.

Evaluation of the Electroconvulsive Therapy's Impact on Retinal Structures in First-Episode Psychosis Patients Using Optical Coherence Tomography

BACKGROUND AND HYPOTHESIS

Schizophrenia is a complex disorder thought to have neurodevelopmental and neurodegenerative aspects. Optical coherence tomography (OCT) measurements of schizophrenia patients revealed that the retinal layers of these patients were thinner than those of healthy controls. This study aimed to examine retinal changes in first-episode psychosis patients treated with electroconvulsive therapy (ECT) via OCT.

STUDY DESIGN

Thirty first-episode psychosis patients (13 men, 17 women) aged 18 to 65 years who had no comorbidities and no smoking, alcohol, or substance use disorders and who were treated with ECT were included in the study. The patients were evaluated using OCT before treatment and after an average of 7.4 sessions of ECT in remission, and the results were compared.

STUDY RESULTS

Statistically significant increases were observed in retinal layer thickness, inner plexiform layer, outer plexiform layer, and total retinal thickness within the 1 mm ring (P = .015, P = .045, and P = .025, respectively). The inner nuclear layer thickness significantly increased within the 6 mm ring (P = .037).

CONCLUSIONS

In conclusion, ECT noticeably affected retinal structures, particularly according to similar measurements, indicating potential improvements in and the ability to reverse neuronal degeneration after one month of treatment. This study highlights the potential impact of ECT on retinal structures in individuals experiencing first-episode psychosis, as it can enhance specific retinal layers and reverse neuronal degeneration.

Signature of Altered Retinal Microstructures and Electrophysiology in Schizophrenia Spectrum Disorders Is Associated With Disease Severity and Polygenic Risk

BACKGROUND

Optical coherence tomography and electroretinography studies have revealed structural and functional retinal alterations in individuals with schizophrenia spectrum disorders (SSDs). However, it remains unclear which specific retinal layers are affected; how the retina, brain, and clinical symptomatology are connected; and how alterations of the visual system are related to genetic disease risk.

METHODS

Optical coherence tomography, electroretinography, and brain magnetic resonance imaging were applied to comprehensively investigate the visual system in a cohort of 103 patients with SSDs and 130 healthy control individuals. The sparse partial least squares algorithm was used to identify multivariate associations between clinical disease phenotype and biological alterations of the visual system. The association of the revealed patterns with individual polygenic disease risk for schizophrenia was explored in a post hoc analysis. In addition, covariate-adjusted case-control comparisons were performed for each individual optical coherence tomography and electroretinography parameter.

RESULTS

The sparse partial least squares analysis yielded a phenotype-eye-brain signature of SSDs in which greater disease severity, longer duration of illness, and impaired cognition were associated with electrophysiological alterations and microstructural thinning of most retinal layers. Higher individual loading onto this disease-relevant signature of the visual system was significantly associated with elevated polygenic risk for schizophrenia. In case-control comparisons, patients with SSDs had lower macular thickness, thinner retinal nerve fiber and inner plexiform layers, less negative a-wave amplitude, and lower b-wave amplitude.

CONCLUSIONS

This study demonstrates multimodal microstructural and electrophysiological retinal alterations in individuals with SSDs that are associated with disease severity and individual polygenic burden.

Association between polygenic risk for schizophrenia and retinal morphology: A cross-sectional analysis of the United Kingdom Biobank

We examined the relationship between genetic risk for schizophrenia (SZ), using polygenic risk scores (PRSs), and retinal morphological alterations. Retinal structural and vascular indices derived from optical coherence tomography (OCT) and color fundus photography (CFP) and PRSs for SZ were analyzed in N = 35,024 individuals from the prospective cohort study, United Kingdom Biobank (UKB). Results indicated that macular ganglion cell-inner plexiform layer (mGC-IPL) thickness was significantly inversely related to PRS for SZ, and this relationship was strongest within higher PRS quintiles and independent of potential confounders and age. PRS, however, was unrelated to retinal vascular characteristics, with the exception of venular tortuosity, and other retinal structural indices (macular retinal nerve fiber layer [mRNFL], inner nuclear layer [INL], cup-to-disc ratio [CDR]). Additionally, the association between greater PRS and reduced mGC-IPL thickness was only significant for participants in the 40-49 and 50-59 age groups, not those in the 60-69 age group. These findings suggest that mGC-IPL thinning is associated with a genetic predisposition to SZ and may reflect neurodevelopmental and/or neurodegenerative processes inherent to SZ. Retinal microvasculature alterations, however, may be secondary consequences of SZ and do not appear to be associated with a genetic predisposition to SZ.

Retinal layers and symptoms and inflammation in schizophrenia

Schizophrenia is a neurodevelopmental disorder that affects brain structure and function. The retina, as well as the brain, consists of neuronal and glial cells packed in layers. Cortical volume and brain thickness are associated with inflammatory biomarkers, however, no study has been performed associating inflammatory biomarkers and retina in schizophrenia. our study aims to compare the retinal macular thickness and volume and peripapillary thickness in patients with schizophrenia and controls, and associate it to symptoms of schizophrenia, to interleukin-6 (IL-6) and C Reactive Protein (CRP) levels. Optical coherence tomography was performed to assess retinal layer thickness and volume, and CRP and IL-6 levels were measured in patients with schizophrenia and controls. Positive, negative, and general symptoms of schizophrenia were measured with the Positive and Negative Syndrome Scale (PANSS). A linear regression controlling for confounding factors was performed. 70 subjects were included, 35 patients, and 35 controls matched for sex and age. Patients with schizophrenia presented a significantly lower macular volume (p < 0.05) and thickness (< 0.05) than controls. PANSS positive, general and total scores were associated with retinal nerve fiber layer (RNFL) thickness (p < 0.05). There was no association between inflammatory markers (CRP and IL-6) levels and the retinal layer. A reduction in macular volume and thickness was found in patients with schizophrenia. The severity of schizophrenia symptoms was associated with RNFL thickness. CRP and IL-6 are not associated with retinal thickness/volume in schizophrenia or controls.

Specific association between retinal neural layer thinning and neurological soft signs in schizophrenia

There is growing evidence of disproportionate retinal thinning in schizophrenia, but doubts are still raised regarding its significance in the context of the neurobiology of the disease. Therefore, we examined whether these abnormalities are significantly associated with neurological soft signs (NSS) which are closely related to the risk of schizophrenia. This cross-sectional study analyzing linear correlations between variables involved 56 schizophrenia inpatients and 60 controls. The results confirmed such relationships, and only in the patient sample. In addition, retinal abnormalities and NSS were significantly correlated with duration of illness. These findings provide further evidence for linked neurodevelopmental and neurodegenerative aspects of schizophrenia.

Retina as a potential biomarker in schizophrenia spectrum disorders: a systematic review and meta-analysis of optical coherence tomography and electroretinography

INTRODUCTION

Abnormal findings on optical coherence tomography (OCT) and electroretinography (ERG) have been reported in participants with schizophrenia spectrum disorders (SSDs). This study aims to reveal the pooled standard mean difference (SMD) in retinal parameters on OCT and ERG among participants with SSDs and healthy controls and their association with demographic characteristics, clinical symptoms, smoking, diabetes mellitus, and hypertension.

METHODS

Using PubMed, Scopus, Web of Science, and PSYNDEX, we searched the literature from inception to March 31, 2023, using specific search terms. This study was registered with PROSPERO (CRD4202235795) and conducted according to PRISMA 2020.

RESULTS

We included 65 studies in the systematic review and 44 in the meta-analysis. Participants with SSDs showed thinning of the peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell layer- inner plexiform cell layer, and retinal thickness in all other segments of the macula. A meta-analysis of studies that excluded SSD participants with diabetes and hypertension showed no change in results, except for pRNFL inferior and nasal thickness. Furthermore, a significant difference was found in the pooled SMD of pRNFL temporal thickness between the left and right eyes. Meta-regression analysis revealed an association between retinal thinning and duration of illness, positive and negative symptoms. In OCT angiography, no differences were found in the foveal avascular zone and superficial layer foveal vessel density between SSD participants and controls. In flash ERG, the meta-analysis showed reduced amplitude of both a- and b-waves under photopic and scotopic conditions in SSD participants. Furthermore, the latency of photopic a-wave was significantly shorter in SSD participants in comparison with HCs.

DISCUSSION

Considering the prior report of retinal thinning in unaffected first-degree relatives and the results of the meta-analysis, the findings suggest that retinal changes in SSDs have both trait and state aspects. Future longitudinal multimodal retinal imaging studies are needed to clarify the pathophysiological mechanisms of these changes and to clarify their utility in individual patient monitoring efforts.

Exploring depression in people with schizophrenia spectrum disorders: A cross-sectional analysis of the clinical relationship with Positive and Negative Syndrome Scale dimensions

OBJECTIVE

Evidence on the relationship between depression and clinical dimensions of schizophrenia remains limited. This cross-sectional study investigated the association between depression and Positive and Negative Syndrome Scale (PANSS) dimensions in people with schizophrenia spectrum disorders.

METHODS

Trained assessors administered the PANSS to measure symptoms of schizophrenia and the Calgary Depression Scale for Schizophrenia to measure depression. The association of depression with overall PANSS score and related dimensions was investigated in multiple logistic regression analyses.

RESULTS

We included 231 inpatients with schizophrenia spectrum disorders (mean age: 42.4 (SD: 12.9) years; men: 58.9%; mean overall PANSS score: 82.5 (SD: 20.1); drug-free or naïve: 39.3%), including 78 (33.8%) with clinically significant depressive symptoms. Depression was associated with higher overall (regression coefficient, SE: 0.029, 0.008; p < 0.001) and general psychopathology (regression coefficient, SE: 0.118, 0.023; p < 0.001) PANSS scores. We found an inverse relationship between depression and positive symptoms (regression coefficient, SE: -0.088, 0.028; p = 0.002). No association between depression and negative symptoms was found.

CONCLUSION

Despite some limitations, our study shows that people affected by schizophrenia spectrum disorders with depression are likely to show more overall and general psychopathology symptoms but lower positive symptoms. Additional studies are needed to explore the generalizability of our findings.

Clinical and biological correlates of optical coherence tomography findings in schizophrenia

There is a growing body of evidence indicating retinal layer thinning in schizophrenia. However, neuropathological processes underlying these retinal structural changes and its clinical correlates are yet to be known. Here, we aim to investigate the clinical and biological correlates of OCT findings in schizophrenia. 50 schizophrenia patients and 40 healthy controls were recruited. Retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), and macular and choroidal thicknesses were recorded. A comprehensive battery of neuropsychological tests was applied. Fasting glucose, triglycerides and HDL-cholesterol levels, TNF-α, IL-1β and IL-6 levels were measured. Right IPL was significantly thinner in patients than the controls after controlling for various confounders (F = 5.42, p = .02). Higher IL-6, IL-1β, and TNF-α levels were associated with decreased left macular thickness (r =  - 0.26, p = .027, r =  - 0.30, p = 0.012, and r =  - 0.24, p = .046, respectively) and higher IL-6 was associated with thinning of right IPL (r =  - 0.27, p = 0.023) and left choroid (r =  - 0.23, p = .044) in the overall sample. Thinning of right IPL and left macula were also associated with worse executive functioning (r = 0.37, p = 0.004 and r = 0.33, p = 0.009) and attention (r = 0.31, p = 0.018 and r = 0.30, p = 0.025). In patients with schizophrenia, IPL thinning was associated with increased BMI (r =  - 0.44, p = 0.009) and decreased HDL levels (r = 0.43, p = 0.021). Decreased TNF-α level was related to IPL thinning, especially in the left eye (r = 0.40, p = 0.022). These findings support the hypothesis that OCT might provide the opportunity to establish an accessible and non-invasive probe of brain pathology in schizophrenia and related disorders. However, future studies investigating retinal structural changes as a biological marker for schizophrenia should also consider the metabolic state of the subjects.

A systematic review and meta-analysis of optical coherence tomography studies in schizophrenia, bipolar disorder and major depressive disorder

OBJECTIVES

Due to the common neurodevelopmental origin and easy accessibility, the retina serves as a surrogate marker for changes in the brain. Hence, Optical Coherence Tomography (OCT), a tool to examine the neuronal layers of retina has gained importance in investigating psychiatric disorders. Several studies in the last decade have reported retinal structural alterations in schizophrenia (SCZ), bipolar disorder (BD), and major depressive disorder (MDD). However, the findings are inconsistent. Hence, we conducted a meta-analysis to investigate alterations in OCT parameters in patients with SCZ, BD and MDD.

METHODS

We searched electronic databases for studies that examined OCT parameters in patients with SCZ, BD and MDD published up to January 2023. The primary outcome measures were thickness and volumes of the retinal Nerve Fibre Layer (RNFL). We conducted meta-analysis using a random effects model.

RESULTS

The searches yielded 2638 publications of which 43 studies were included in the final analysis across all disorders. Compared to controls, the RNFL was thinner in SCZ patients (SMD = -0.37, p = <0.001) and BD patients (SMD = -0.67, p = < 0.001), but not in MDD patients (SMD = -0.08, p = 0.54). On quadrant wise analysis, temporal quadrant RNFL was thinner in SCZ but not in BD, while all other quadrants were thinner in both SCZ and BD.

CONCLUSION

We found significant reductions in RNFL thickness in SCZ and BD, but not in MDD. The differential involvement in various quadrants and parameters across the disorders has potential implications for using retinal parameters as a diagnostic biomarker.

Retinal Neurodegeneration as a Potential Biomarker of Accelerated Aging in Schizophrenia Spectrum Disorders

BACKGROUND AND HYPOTHESES

Several biological markers are believed to reflect accelerated aging in schizophrenia spectrum disorders; however, retinal neural changes have not yet been explored as potential CNS biomarkers of accelerated aging in this population. The aim of this study was to determine whether retinal neural layer thinning is more strongly related to age in schizophrenia and schizoaffective disorder patients (SZ) than in a psychiatrically healthy control group (CON).

STUDY DESIGN

Schizophrenia (n = 60) and CON participants (n = 69) underwent spectral domain optical coherence tomography (OCT) scans to examine the following variables in both eyes: retinal nerve fiber layer (RNFL) thickness, macula central subfield (CSF) thickness, macula volume, ganglion cell layer-inner plexiform layer (GCL-IPL) thickness, optic cup volume, and cup-to-disc ratio. Eleven participants in each group had diabetes or hypertension.

STUDY RESULTS

Significant negative relationships between age and RNFL thickness, macula volume, and GCL-IPL thickness were observed in the SZ group, while no significant relationships were observed in the CON group. However, many of the findings in the SZ group lost significance when participants with diabetes/hypertension were removed from analyses. A notable exception to this was that the age × SZ interaction accounted for a unique proportion of variance in GCL-IPL thinning over and above the effect of diabetes/hypertension.

CONCLUSIONS

The results suggest that retinal atrophy occurs at an increased rate in schizophrenia spectrum disorders, potentially reflecting accelerated aging inherent to these conditions, with considerable contributions from systemic medical diseases closely linked to this population.

Differentiation of the retinal morphology aging trajectories in schizophrenia and their associations with cognitive dysfunctions

Previous studies evaluating the morphology of the selected retinal layers in schizophrenia showed abnormalities regarding macular thickness, retinal nerve fiber layer (RNLF), and ganglion cell complex (GCC). Concurrently, accumulating neuroimaging results suggest that structural alterations of the brain in this disease might be an effect of accelerated aging. Referring to these findings, we aimed to determine whether the thinning of the retinal layers assessed with the optic coherence tomography (OCT) in a group of schizophrenia patients (n = 60) presents a significant age-related decrease exceeding potential changes noted in the control group (n = 61). Samples of patients and controls were divided into three age subgroups, namely, younger, middle-aged, and older participants. OCT outcomes, such as macular thickness and volume, macular RNFL, peripapillary RNFL, and GCC, were analyzed concerning a diagnosis status (controls vs. patients) and age subgroups. Additionally, associations between retinal parameters, age, and selected cognitive functions were evaluated. post-hoc tests revealed that macular thickness and volume in patients undergo significant age-dependent thinning, which was not observed in the control group. Regression analyses confirmed the association between macular morphology and age. Selected speed-dependent cognitive functions in patients decreased significantly with age, and these features were also significantly associated with some OCT outcomes also after controlling for antipsychotic treatment. Our results suggest that reduced measures of retinal structure detected in schizophrenia may be an effect of accelerated aging; however, further research is needed using computational solutions derived from brain imaging studies based on large datasets covering representatives of all age groups.

Age of Onset Moderates the Association between Total Antioxidant Capacity and Cognitive Deficits in Patients with Drug-Naïve Schizophrenia

Schizophrenia patients with an earlier age of onset have been found to have more serious negative symptoms and cognitive deficits. Oxidative stress is thought to be implicated in cognitive impairment in schizophrenia. Total antioxidant capacity (TAOC) is an essential indicator of oxidative stress. However, the association between age of onset, TAOC, and cognitive performance in schizophrenia remains unexplored. In this study, 201 patients (age: 26.5 ± 9.6 years; male: 53.2%) with drug-naïve schizophrenia were recruited. Clinical symptoms were evaluated using the Positive and Negative Syndrome Scale (PANSS). Cognitive functioning was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Plasma TAOC levels were analyzed using established procedures. Results showed that early-onset (EO) patients had higher TAOC levels, more severe negative symptoms and performed worse on visuospatial/constructional, language and RBANS total scores than non-EO patients. After Bonferroni correction, only non-EO patients showed a significant inverse relationship between TAOC levels and RBANS language, attention, and total scores. Our findings suggest that an early/late age of onset may be correlated with psychopathological symptoms, cognitive impairment and oxidative responses in schizophrenia. Furthermore, the age of onset may moderate the relationship between TAOC and cognitive function in patients with schizophrenia. These findings suggest that improving oxidative stress status in non-EO schizophrenia patients may enhance their cognitive function.

The multimodal Munich Clinical Deep Phenotyping study to bridge the translational gap in severe mental illness treatment research

Introduction

Treatment of severe mental illness (SMI) symptoms, especially negative symptoms and cognitive dysfunction in schizophrenia, remains a major unmet need. There is good evidence that SMIs have a strong genetic background and are characterized by multiple biological alterations, including disturbed brain circuits and connectivity, dysregulated neuronal excitation-inhibition, disturbed dopaminergic and glutamatergic pathways, and partially dysregulated inflammatory processes. The ways in which the dysregulated signaling pathways are interconnected remains largely unknown, in part because well-characterized clinical studies on comprehensive biomaterial are lacking. Furthermore, the development of drugs to treat SMIs such as schizophrenia is limited by the use of operationalized symptom-based clusters for diagnosis.

Methods

In line with the Research Domain Criteria initiative, the Clinical Deep Phenotyping (CDP) study is using a multimodal approach to reveal the neurobiological underpinnings of clinically relevant schizophrenia subgroups by performing broad transdiagnostic clinical characterization with standardized neurocognitive assessments, multimodal neuroimaging, electrophysiological assessments, retinal investigations, and omics-based analyzes of blood and cerebrospinal fluid. Moreover, to bridge the translational gap in biological psychiatry the study includes in vitro investigations on human-induced pluripotent stem cells, which are available from a subset of participants.

Results

Here, we report on the feasibility of this multimodal approach, which has been successfully initiated in the first participants in the CDP cohort; to date, the cohort comprises over 194 individuals with SMI and 187 age and gender matched healthy controls. In addition, we describe the applied research modalities and study objectives.

Discussion

The identification of cross-diagnostic and diagnosis-specific biotype-informed subgroups of patients and the translational dissection of those subgroups may help to pave the way toward precision medicine with artificial intelligence-supported tailored interventions and treatment. This aim is particularly important in psychiatry, a field where innovation is urgently needed because specific symptom domains, such as negative symptoms and cognitive dysfunction, and treatment-resistant symptoms in general are still difficult to treat.