Aberrant Interhemispheric Functional Connectivity in Diabetic Retinopathy Patients

Genetic mechanisms of hemispheric functional connectivity in diabetic retinopathy: a joint neuroimaging and transcriptomic study

Background

DR represents a major cause of global vision loss; however, the genetic basis of functional homotopy,a critical neurobiological metric reflecting interhemispheric functional synchronization, remains largely unexplored. Emerging evidence suggests that DR patients exhibiting aberrant VMHC may potentially associate with distinct transcriptional profiles. These findings could provide novel mechanistic insights into the neuropathological substrates underlying DR-related visual and cognitive dysfunction.

Methods

Resting-state fMRI data from 46 DR patients and 43 HCs were analyzed to compute VMHC for assessing interhemispheric functional connectivity. Spatial transcriptomic-neuroimaging associations were examined using AHBA, revealing genes significantly correlated with VMHC alterations. Subsequent analyses included functional enrichment assessment and PPI network construction.

Results

DR patients demonstrated significantly lower VMHC in bilateral LING, PoCG, and PreCG versus controls, indicating impaired interhemispheric connectivity in visual-sensorimotor networks. VMHC variations spatially correlated with 4,000 genes (2,000 positive/negative each), enriched in transcriptional regulation, mitochondrial function, synaptic activity (BP/CC/MF), and lipid metabolism/N-glycan biosynthesis (KEGG). PPI network identified hub genes (ACTB/MRPL9/MRPS6,positive; H4C6/NDUFAB1/H3C12,negative) regulating mitochondrial dynamics, cytoskeleton, and epigenetics.

Conclusion

This study represents the first integration of fMRI and transcriptomics to elucidate the genetic determinants underlying VMHC disruption in DR. The findings demonstrate that impaired interhemispheric connectivity in DR involves complex interactions among genes regulating neurovascular, metabolic, and neurodegenerative pathways. These results significantly advance the understanding of neurological manifestations in DR and identify potential therapeutic targets for clinical intervention.

Brain white matter microstructural alterations in patients with diabetic retinopathy: an automated fiber-tract quantification study

Background

Cognitive decline may occur in patients with diabetic retinopathy (DR), yet the mechanism underlying the relationship between cognitive decline and DR remains unclear. This study applied an automated fiber-tract quantification (AFQ) technique based on diffusion tensor imaging (DTI) to identify alterations in specific segments of brain white matter fiber tracts in patients with DR, and analyze their correlation with cognitive test scores and clinical biochemical indicators.

Methods

A total of 19 patients with DR and 20 age-, sex-, and education-matched healthy controls (HCs) were included. Clinical and imaging data were prospectively collected. The AFQ technique was applied to track the whole brain white matter fiber tracts of each participant, and each fiber tract was segmented into 100 equidistant nodes. The fractional anisotropy (FA), mean diffusion (MD), axial diffusion (AD), and radial diffusion in 100 nodes of each fiber tract were calculated and compared between the two groups. Partial correlation analysis was performed to analyze the correlation between altered DTI metrics in segments of the fiber tracts and cognitive test scores, as well as clinical biochemical indicators in patients with DR.

Results

Compared with the HC group, the DR group showed significantly reduced FA values in nodes 81-100, increased MD values in nodes 39-50, and reduced AD values in nodes 91-100 of the left cingulum cingulate (CGC) [P<0.05, false discovery rate (FDR) corrected], they also showed increased AD values in the left superior longitudinal fasciculus (SLF; nodes 1-23, 37-50, and 66-99), and the right SLF (nodes 1-36 and 79-100) (P<0.05, FDR corrected). Correlation analysis revealed a positive correlation between the FA values in nodes 82-98 of the left CGC and Montreal Cognitive Assessment scores (MoCA scores, r=0.760, P<0.05/P=0.021), and a positive correlation between the AD values in nodes 37-41 in the left SLF and glycated hemoglobin A1c (HbA1c) levels (r=0.559, P<0.05/P=0.039).

Conclusions

Our findings demonstrated alterations in the white matter fiber tracts at the point-wise level in patients with DR using AFQ analysis. These alterations may be associated with cognitive impairment in DR. The AFQ technique can accurately detect the damage to the integrity of the brain white matter fiber tracts in patients with DR, and have high clinical application value in the diagnosis and evaluation of DR, which can deepen our understanding of brain white matter microstructural abnormalities in patients with DR.

Investigation of the static and dynamic brain network mechanisms in patients with rhegmatogenous retinal detachment based on independent component analysis

BACKGROUND

Previous neuroimaging studies have identified substantial structural and functional abnormalities in the brains of patients with rhegmatogenous retinal detachment (RRD). Nonetheless, there remains a paucity of comprehensive research on the alterations in functional connectivity (FC) within large-scale static and dynamic brain networks in these patients.

METHODS

This study utilized independent component analysis (ICA) to investigate alterations in large-scale brain network FC in patients with RRD. Additionally, it employed support vector machine (SVM) to classify RRD patients and healthy controls (HCs) and examined the relationship between abnormal brain regions and clinical ophthalmic parameters.

RESULTS

The RRD patients demonstrated significantly increased FC in the default mode network (DMN) and visual network (VN) compared to the HCs, whereas the FC in the auditory network (AN) and the sensorimotor network (SMN) was significantly decreased. Analysis of dynamic functional network connectivity (dFNC) revealed that the fraction of time (FT) spent in state 4 was significantly greater in RRD patients compared to HCs. SVM analysis showed that the AUC for classification using AN and FNC features reached 0.828 and 0.819, respectively. Additionally, the FC value of the right medial superior frontal gyrus (R-SFGmed) in RRD patients was positively correlated with axial length (r = 0.401, p = 0.038).

CONCLUSION

This study revealed that patients with RRD exhibit both damage and adaptive remodeling in their brain functional networks. Alterations in the AN and FNC may serve as potential neuroimaging biomarkers for distinguishing RRD patients from HCs, providing crucial neuroimaging evidence for understanding the mechanisms underlying visual loss in RRD.

Altered Interhemispheric Functional Connectivity in Patients With Diabetic Retinopathy: A Resting-State Functional MRI Study

OBJECTIVE

Cognitive impairment is a prevalent complication among patients with diabetes mellitus. It tends to be more prominent in patients with diabetic retinopathy (DR) compared with patients with diabetes without DR (NDR). However, the functional connectivity (FC) between bilateral cerebral hemispheres in both remains poorly understood. This study aimed to investigate altered brain connectivity in patients with DR and NDR.

SUBJECTS AND METHODS

We selected 26 patients with DR, 30 patients with NDR, and 30 healthy controls (HCs) to participate in resting-state functional magnetic resonance imaging (rs-fMRI) and high-resolution T1-weighted structural scans. We employed the DPABI toolbox in MATLAB to preprocess the acquired images and applied voxel-mirrored homotopic connectivity (VMHC) and FC analysis methods to estimate differences among the 3 groups. The patients also underwent neuropsychological assessment scales. We utilized partial correlation analysis to explore the associations between aberrant connections and clinical variables as well as neuropsychological characteristics in patients with DR. Receiver operating characteristic (ROC) analysis was conducted to assess the diagnostic performance of VMHC values in distinct brain regions for differentiating DR patients from NDR patients.

RESULTS

The results showed significantly altered VMHC values across the 3 groups, including bilateral lingual gyrus (LING_B), superior temporal gyrus (STG_B), and postcentral gyrus (PoCG_B). Significant differences in FC values were found across the LING_B, right cuneus (CUN_R), STG_R, PoCG_B, right precentral gyrus (PreCG_R), right precuneus (PCUN_R), and middle temporal gyrus (MTG_L) among the 3 groups. Moreover, a negative correlation was noted between the VMHC values of LING_B and disease duration in patients with DR. Positive correlations were detected between FC values in PoCG_B and fasting blood glucose (FBG) levels. Furthermore, ROC analysis of the VMHC values demonstrated that combining all the differential regions achieved the highest area under the curve of 0.826.

CONCLUSIONS

Significant alterations in VMHC and FC may reflect the underlying neuropathology of cognitive dysfunction in DR and NDR. These altered connectivity patterns could serve as neuroimaging biomarkers, offering insights into the early diagnosis and intervention of cognitive impairments in DR patients.

Brain structural changes in diabetic retinopathy patients: a combined voxel-based morphometry and surface-based morphometry study

The aim of this study was to investigate alterations in gray matter structure among individuals diagnosed with diabetic retinopathy (DR). This study included a cohort of 32 diabetic patients with retinopathy (DR group, n = 32) and 38 healthy adults (HC group, n = 38). Both cohorts underwent comprehensive psychological and cognitive assessments alongside structural magnetic resonance imaging. The brain's gray matter volume and morphology were analyzed using voxel-based morphometry (VBM) and surface-based morphometry (SBM). Partial correlation analysis was employed to investigate the associations between differences in gray matter volume (GMV) across diverse brain regions and the outcomes of cognitive psychological tests as well as clinical indicators. The VBM results revealed that, in comparison to the healthy control (HC) group, patients with diabetic retinopathy (DR) exhibited reduced gray matter volume (GMV) in the right fusiform gyrus, inferior frontal gyrus, opercular part, and left hippocampus; conversely, an increase in GMV was observed in the right thalamus. The SBM results indicated cortical thinning in the left caudal anterior cingulate cortex, left superior frontal gyrus, left parahippocampal gyrus, and bilateral lingual gyrus in the DR group. Sulcal depth (SD) exhibited increased values in the bilateral rostral middle frontal gyrus, superior frontal gyrus, frontal pole, left precentral gyrus, postcentral gyrus, lateral orbitofrontal gyrus, and right paracentral gyrus. Local gyrification indices (LGIs) decreased in the left caudal middle frontal gyrus and superior frontal gyrus. The fractal dimension (FD) decreased in the posterior cingulate gyrus and isthmus of the cingulate gyrus. The left hippocampal gray matter volume (GMV) in patients with diabetic retinopathy was negatively correlated with disease duration (r = -0.478, p = 0.008) and self-rating depression scale (SAS) score (r = -0.381, p = 0.038). The structural alterations in specific brain regions of individuals with DR, which may contribute to impairments in cognition, emotion, and behavior, provide valuable insights into the neurobiological basis underlying these dysfunctions.

Aberrant Neurovascular Coupling in Diabetic Retinopathy Using Arterial Spin Labeling (ASL) and Functional Magnetic Resonance Imaging (fMRI) methods

Background

Previous imaging studies have demonstrated that diabetic retinopathy (DR) is linked to structural and functional abnormalities in the brain. However, the extent to which DR patients exhibit abnormal neurovascular coupling remains largely unknown.

Methods

Thirty-one patients with DR and 31 sex- and age-matched healthy controls underwent resting-state functional magnetic resonance imaging (rs-fMRI) to calculate functional connectivity strength (FCS) and arterial spin-labeling imaging (ASL) to calculate cerebral blood flow (CBF). The study compared CBF-FCS coupling across the entire grey matter and CBF/FCS ratios (representing blood supply per unit of connectivity strength) per voxel between the two groups. Additionally, a support vector machine (SVM) method was employed to differentiate between diabetic retinopathy (DR) patients and healthy controls (HC).

Results

In DRpatients compared to healthy controls, there was a reduction in CBF-FCS coupling across the entire grey matter. Specifically, DR patients exhibited elevated CBF/FCS ratios primarily in the primary visual cortex, including the right calcarine fissure and surrounding cortex. On the other hand, reduced CBF/FCS ratios were mainly observed in premotor and supplementary motor areas, including the left middle frontal gyrus.

Conclusion

An elevated CBF/FCS ratio suggests that patients with DR may have a reduced volume of gray matter in the brain. A decrease in its ratio indicates a decrease in regional CBF in patients with DR. These findings suggest that neurovascular decoupling in the visual cortex, as well as in the supplementary motor and frontal gyrus, may represent a neuropathological mechanism in diabetic retinopathy.

Alterations of spontaneous brain activity in type 2 diabetes mellitus without mild cognitive impairment: a resting-state functional magnetic resonance study

Background

Type 2 diabetes mellitus (T2DM) has been demonstrated an increased risk factor of cognitive impairment or even dementia. Kinds of resting-state functional magnetic resonance imaging indices have been proposed and used to investigate the brain mechanism underlying diabetic cognitive impairment. This study aimed to explore the early changes in spontaneous neural activity among T2DM patients without cognitive impairment by means of multiple rs-fMRI indices.

Methods

T2DM patients without cognitive impairment and age-, sex-, and education matched control subjects were included in this study. Three rs-fMRI indices, namely amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo) and voxel-mirrored homotopic connectivity (VMHC) were computed after image pre-processing. The Montreal Cognitive Assessment (MoCA) was performed to distinguish normal cognition. Brain volume was also evaluated. Correlation analyses were conducted to explore any relationship among rs-fMRI indices and clinical characteristics.

Results

The T2DM patients were detected significantly decreased neural activity in right angular and left prefrontal gyrus including middle and superior frontal gyrus. Increased activities were also observed in left caudate and the supplementary motor area. No correlation between rs-fMRI indices and clinical characteristics was survived after multiple comparison correction. But we observed a significant, but decreased correlation between ALFF and ReHo values in the reported brain areas.

Conclusion

The combination of ALFF, ReHo and VMHC analyses demonstrated abnormal spontaneous neural activity in brain regions which were reported in T2DM patients without cognitive impairment. These results may enhance our understanding of the diabetic brain changes at the early stage.

Altered functional connectivity between the default mode network in diabetic retinopathy patients

OBJECTIVES

Previous studies have demonstrated that diabetic retinopathy is associated with cognitive impairment. This study aimed to investigate the intrinsic functional connectivity pattern within the default mode network (DMN) and its associations with cognitive impairment in diabetic retinopathy patients using resting-state functional MRI (rs-fMRI).

METHODS

A total of 34 diabetic retinopathy patients and 37 healthy controls were recruited for rs-fMRI scanning. Both groups were age, gender, and education level matched. The posterior cingulate cortex (PCC) was chosen as the region of interest for detecting functional connectivity changes.

RESULTS

Compared with the healthy control group, diabetic retinopathy patients showed increased functional connectivity between PCC and left medial superior frontal gyrus and increased functional connectivity between PCC and right precuneus.

CONCLUSION

Our study highlights that diabetic retinopathy patients show enhanced functional connectivity within DMN, suggesting that a compensatory increase of neural activity might occur in DMN, which offers new insight into the potential neural mechanism of cognitive impairment in diabetic retinopathy patients.

Neurovascular decoupling measured with quantitative susceptibility mapping is associated with cognitive decline in patients with type 2 diabetes

Disturbance of neurovascular coupling (NVC) is suggested to be one potential mechanism in type 2 diabetes mellitus (T2DM) associated mild cognitive impairment (MCI). However, NVC evidence derived from functional magnetic resonance imaging ignores the relationship of neuronal activity with vascular injury. Twenty-seven T2DM patients without MCI and thirty healthy controls were prospectively enrolled. Brain regions with changed susceptibility detected by quantitative susceptibility mapping (QSM) were used as seeds for functional connectivity (FC) analysis. NVC coefficients were estimated using combined degree centrality (DC) with susceptibility or cerebral blood flow (CBF). Partial correlations between neuroimaging indicators and cognitive decline were investigated. In T2DM group, higher susceptibility values in right hippocampal gyrus (R.PHG) were found and were negatively correlated with Naming Ability of Montreal Cognitive Assessment. FC increased remarkably between R.PHG and right middle temporal gyrus (R.MTG), right calcarine gyrus (R.CAL). Both NVC coefficients (DC-QSM and DC-CBF) reduced in R.PHG and increased in R.MTG and R.CAL. Both NVC coefficients in R.PHG and R.MTG increased with the improvement of cognitive ability, especially for executive function. These demonstrated that QSM and DC-QSM coefficients can be promising biomarkers for early evaluation of cognitive decline in T2DM patients and help to better understand the mechanism of NVC.