Superior Longitudinal Fasciculus Research Articles

Long-Term Post-Stroke Cognition in Patients With Minor Ischemic Stroke is Related to Tract-Based Disconnection Induced by White Matter Hyperintensities.

Over a third of minor stroke patients experience post-stroke cognitive impairment (PSCI), but no validated tools exist to identify at-risk patients early. This study investigated whether disconnection features derived from infarcts and white matter hyperintensities (WMH) could serve as markers for short- and long-term cognitive decline in first-ever minor ischemic stroke patients. First-ever minor ischemic stroke patients (NIHSS ≤ 7) were prospectively followed at 72-h, 6 months, and 36 months post-stroke with cognitive tests and brain MRI. Infarct and WMH volumes were semi-automatically assessed on DWI and FLAIR sequences. Bayesian tract-based disconnection models estimated remote pathological effects of infarcts and WMH. Associations between disconnection features and cognitive outcomes were analyzed using canonical correlation analyses, adjusted for age, education, and multiple comparisons. Among 105 patients (31% female, mean age 63 ± 12 years), infarct volume averaged 10.28 ± 17.10 cm3 and predominantly involved the middle cerebral artery territory (83%). WMH burden was higher in frontal periventricular white matter. Infarct-based features did not significantly relate to PCSI. However, a WMH-derived disconnection factor, involving commissural and frontal tracts, and the right superior longitudinal fasciculus, was significantly associated with PSCI at 6 months (OR = 9.96, p value = 0.02) and 36 months (OR = 12.27, p value = 0.006), particularly in executive/attention, language, and visuospatial domains. This factor, unrelated to WMH volume, outperformed demographic and clinical predictors of PSCI. WMH-induced disconnection may be associated with short- and long-term PSCI in minor stroke. Routine MR-derived features could identify at-risk patients for rehabilitation trials.

Obstructive sleep apnea and structural and functional brain alterations: a brain-wide investigation from clinical association to genetic causality

BackgroundObstructive sleep apnea (OSA) is linked to brain alterations, but the specific regions affected and the causal associations between these changes remain unclear.MethodsWe studied 20 pairs of age-, sex-, BMI-, and education- matched OSA patients and healthy controls using multimodal magnetic resonance imaging (MRI) from August 2019 to February 2020. Additionally, large-scale Mendelian randomization analyses were performed using genome-wide association study (GWAS) data on OSA and 3935 brain imaging-derived phenotypes (IDPs), assessed in up to 33,224 individuals between December 2023 and March 2024, to explore potential genetic causality between OSA and alterations in whole brain structure and function.ResultsIn the cohort study, OSA patients exhibited significantly lower fractional amplitude of low-frequency fluctuation and regional homogeneity in the right posterior cerebellar lobe and bilateral superior and middle frontal gyrus, while showing higher levels in the left occipital lobe and left posterior central gyrus. Decreased fractional anisotropy (FA) but increased apparent diffusion coefficient (ADC) was shown in the bilateral superior longitudinal fasciculus. According to the results of Affiliation file 2: table s6, it is the ADC value of right superior longitudinal fasciculus was shown a positive correlation with the lowest oxygen saturation. In the Mendelian randomization analyses, the area of left inferior temporal sulcus (OR: 0.89; 95% CI: 0.82–0.96), rfMRI connectivity ICA100 edge 893 (OR: 0.88; 95% CI: 0.82–0.96), ICA100 edge 951 (OR: 0.89; 95% CI: 0.82–0.97), and ICA100 edge 1213 (OR: 0.89; 95% CI: 0.82–0.96) were significantly decreased in OSA. Conversely, mean thickness of G-front-inf-Triangul in right hemisphere (OR: 1.14; 95% CI: 1.05–1.23), mean orientation dispersion index in right tapetum (OR: 1.13; 95% CI: 1.04–1.23), and rfMRI connectivity ICA100 edge 258 (OR: 1.13; 95% CI: 1.04–1.22) showed opposite results.ConclusionsNerve fiber damage and imbalances in neuronal activity across multiple brain regions caused by hypoxia, particularly the frontal lobe, underlie the structural and the functional connectivity impairments in OSA.

Associations of Maternal Prenatal Zinc Consumption with Infant Brain Tissue Organization and Neurodevelopmental Outcomes.

While studies in rat pups suggest that early zinc exposure is critical for optimal brain structure and function, associations of prenatal zinc intake with measures of brain development in infants are unknown. This study aimed to assess the associations of maternal zinc intake during pregnancy with MRI measures of brain tissue microstructure and neurodevelopmental outcomes, as well as to determine whether MRI measures of the brain mediated the relationship between maternal zinc intake and neurodevelopmental indices. Forty-one adolescent mothers were recruited for a longitudinal study during pregnancy. Maternal zinc intake was assessed during the third trimester of pregnancy using a 24 h dietary recall. Infant MRI scans were acquired at 3 weeks postpartum using a 3.0 Tesla scanner to measure fractional anisotropy (FA) and mean diffusivity (MD). Cognitive, language, and motor skills were assessed at 4, 14, and 24 months postpartum using the Bayley Scales of Infant Development. Greater prenatal zinc intake was associated with reduced FA in cortical gray matter, particularly in the frontal lobe [medial superior frontal gyrus; β (95% CI) = -1.0 (-1.5, -0.5)], in developing white matter, and in subcortical gray matter nuclei. Greater prenatal zinc intake was associated with reduced MD in cortical gray matter and developing white matter [superior longitudinal fasciculus; -4.4 (-7.1, -1.7)]. Greater maternal zinc intake also was associated with higher cognitive development scores at 14 [0.1 (0.0, 0.1)] and 24 [0.1 (0.0, 0.2)] months of age; MRI indices of FA and MD did not mediate this relationship. Maternal prenatal zinc intake was associated with more favorable measures of brain tissue microstructural maturation and cognitive development during infancy.

Effect of physical exercise on white matter microstructure in chemotherapy-treated breast cancer patients: a randomized controlled trial (PAM study).

Physical exercise is a promising intervention to improve brain white matter integrity. In the PAM study, exercise intervention effects on white matter integrity were investigated in breast cancer patients. Chemotherapy-treated breast cancer patients with cognitive problems were randomized 2-4years post-diagnosis to an exercise (n = 91) or control group (n = 90). The 6-month exercise intervention consisted of four hours/week of aerobic and resistance training. White matter integrity was measured at baseline and 6-month follow-up with fractional anisotropy (FA) and mean diffusivity (MD), which were derived from magnetic resonance diffusion tensor imaging (DTI). Both DTI metrics were analyzed whole brain and voxel-wise with a modified tract based spatial statistics (TBSS) procedure. Other measurements included cognition and physical fitness. Exercise effects were analyzed with multiple regression analyses. An explorative analysis was conducted in highly fatigued patients. DTI scans were available for 69 patients of the intervention (age = 52.3 ± 8.9yrs.) and 72 patients of the control group (age = 53.2 ± 8.6yrs.). Whole brain and voxel-wise analyses revealed no significant intervention effects on FA and MD. In highly fatigued patients (exercise: n = 32; control: n = 24), significant clusters of decreased FA post-intervention were observed in the left inferior and superior longitudinal fasciculus. Mean FA in these clusters was not predictive of cognition. A 6-month exercise intervention did not affect white matter integrity in chemotherapy-treated breast cancer patients. However, in highly fatigued breast cancer patients a significant FA decrease was observed post-intervention. The direction of these results is unexpected, and more research is needed to further understand these results.

Distinct white matter abnormalities and cognitive impairments in deficit schizophrenia: a cross-sectional diffusion tensor imaging study

Deficit schizophrenia (DS), characterized by persistent and primary negative symptoms, is considered a promising homogeneous subtype of schizophrenia. According to the disconnection hypothesis, abnormalities in white matter fibers are common in schizophrenia. However, comprehensive measurement of white matter metrics and exploration of the relationships between neuroanatomical changes and cognitive functions in DS patients are still unknown. A cross-sectional study was conducted, including 35 DS patients, 37 non-deficit schizophrenia (NDS) patients, and 39 healthy controls (HC), all male and matched for age and education level. The tract-based spatial statistics method was performed to detect differences in fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) among these three groups. Cognitive function in DS and NDS patients was assessed using the Mini-Mental State Examination (MMSE) and Mattis Dementia Rating Scale. Correlation analyses were performed between diffusion metrics in regions showing differences and clinical scales. The results showed significant differences in diffusion metrics (FA, RD, AD, MD) across DS, NDS, and HC groups, particularly in the corpus callosum, corona radiata, and thalamic radiations. Compare to NDS, DS patients exhibited more reductions in FA and increases in RD, especially in the right posterior thalamic radiation and right superior longitudinal fasciculus. Correlation analysis revealed that lower FA in specific regions was linked to worse cognitive and clinical symptoms. These findings reinforce the dysconnectivity hypothesis of schizophrenia and highlight the distinct pathological mechanisms of white matter impairments in DS. Correlations in crucial white matter regions suggest disruptions in thalamo-cortical feedback loops, potentially contributing to the cognitive impairments observed. This provides a deeper understanding of how structural brain changes relate to clinical symptoms.

MR study on white matter injury in patients with acute diquat poisoning

To explore the microstructural damage of white matter in acute diquat (DQ) poisoning patients using diffusion kurtosis imaging (DKI) and Tract-based Spatial Statistics (TBSS). This study included 19 DQ poisoning patients and 19 age-matched controls. MRI was performed using a 3.0 T Philips Achieva scanner with sequences including 3D T1WI, T2WI, DWI, 3D T2WI-FLAIR, and DKI (3 b-values, 15 directions). DICOM to NIFTI image form conversion was done using MRIcron's Dcm2niigui, followed by motion and eddy current correction with FSL to create a brain mask. Scalar indicators (MK, AK, RK, FAK) were calculated with DKE software. TBSS was used for spatial normalization, skeletonization, and projection of DKI indices for group analysis with TFCE for multiple comparison correction (P < 0.025). After the screening and enrollment process, 19 DQ-poisoned patients and 19 healthy volunteers were analyzed. No significant age or sex differences were found between groups. For Mean Kurtosis (MK), the right corticospinal tract showed a significant difference with a mean difference of 0.21 (95 % CI: 0.15-0.27) and P = 0.000503. Axial Kurtosis (AK) in the left superior longitudinal fasciculus had a mean difference of 0.18 (95 % CI: 0.12-0.24) and P = 0.0024. Fractional Anisotropy of Kurtosis (FAK) in the right corticospinal tract showed a mean difference of 0.19 (95 % CI: 0.13-0.25) and P = 0.0000318. Axial Kurtosis (AK) positively correlated with blood drug levels (r = 0.52, P < 0.05). Seven patients developed subcortical leukodystrophy, mainly in the frontal parietal lobe, with possible insular lobe involvement. DQ poisoning primarily damages the right corticospinal tract, right cingulate gyrus, and left superior longitudinal fasciculus, potentially causing movement and visual impairments. The injury involves demyelination and axonal degeneration, with asymmetrical damage between hemispheres. The left superior longitudinal fasciculus injury is dose-dependent, and unlike prior studies, dopaminergic nuclei were unaffected. The frontal parietal lobe is predominantly affected, with some insular lobe involvement in DQ poisoning patients.

SKELETAL MUSCLE MITOCHONDRIAL FUNCTION AND LONGITUDINAL CHANGES IN BRAIN STRUCTURE

Abstract Mitochondrial dysfunction, a hallmark of aging, has been associated with future cognitive impairment or dementia, as well as PET and blood biomarkers of Alzheimer’s disease and neurodegeneration. Whether mitochondrial dysfunction is associated with accelerated loss in brain volumes and microstructural integrity is unknown. We tested the longitudinal association between in vivo muscle mitochondrial oxidative capacity assessed via MR spectroscopy (post-exercise recovery rate of phosphocreatine, kPCr) and changes in brain MRI volumes and DTI microstructure over up to 12 years of follow-up in the Baltimore Longitudinal Study of Aging (2008-2020). In linear mixed effects models, adjusted for demographics, PCr deletion, and physical activity, higher kPCr was associated with less ventricular enlargement, less worsening in MRI-derived brain aging and Alzheimer’s disease scores, and less regional atrophy, especially the primary sensorimotor cortex, temporal white and gray matter, thalamus, occipital areas, cingulate cortex, and cerebellum (n=649). Higher kPCr was also associated with less microstructural integrity loss in white matter tracts connecting identified gray matter areas (n=598). Specific white matter tracts, including splenium of the corpus callosum and superior longitudinal fasciculus showed consistent longitudinal associations in radial diffusivity, but not axial diffusivity, which may indicate demyelination. Higher in vivo mitochondrial function is associated with less worsening in MRI-derived brain aging and Alzheimer’s disease scores, less brain atrophy in specific gray matter regions and less microstructural integrity loss in connecting white matter tracts. Future studies are warranted to investigate the role of CNS mitochondrial function in brain aging and neurodegeneration.

A multisite validation of brain white matter pathways of resilience to chronic back pain.

Chronic back pain (CBP) is a global health concern with significant societal and economic burden. While various predictors of back pain chronicity have been proposed, including demographic and psychosocial factors, neuroimaging studies have pointed to brain characteristics as predictors of CBP. However, large-scale, multisite validation of these predictors is currently lacking. In two independent longitudinal studies, we examined white matter diffusion imaging data and pain characteristics in patients with subacute back pain (SBP) over 6- and 12-month periods. Diffusion data from individuals with CBP and healthy controls (HC) were analyzed for comparison. Whole-brain tract-based spatial statistics analyses revealed that a cluster in the right superior longitudinal fasciculus (SLF) tract had larger fractional anisotropy (FA) values in patients who recovered (SBPr) compared to those with persistent pain (SBPp), and predicted changes in pain severity. The SLF FA values accurately classified patients at baseline and follow-up in a third publicly available dataset (Area under the Receiver Operating Curve ~0.70). Notably, patients who recovered had FA values larger than those of HC suggesting a potential role of SLF integrity in resilience to CBP. Structural connectivity-based models also classified SBPp and SBPr patients from the three data sets (validation accuracy 67%). Our results validate the right SLF as a robust predictor of CBP development, with potential for clinical translation. Cognitive and behavioral processes dependent on the right SLF, such as proprioception and visuospatial attention, should be analyzed in subacute stages as they could prove important for back pain chronicity.

A multisite validation of brain white matter pathways of resilience to chronic back pain

Chronic back pain (CBP) is a global health concern with significant societal and economic burden. While various predictors of back pain chronicity have been proposed, including demographic and psychosocial factors, neuroimaging studies have pointed to brain characteristics as predictors of CBP. However, large-scale, multisite validation of these predictors is currently lacking. In two independent longitudinal studies, we examined white matter diffusion imaging data and pain characteristics in patients with subacute back pain (SBP) over 6- and 12-month periods. Diffusion data from individuals with CBP and healthy controls (HC) were analyzed for comparison. Whole-brain tract-based spatial statistics analyses revealed that a cluster in the right superior longitudinal fasciculus (SLF) tract had larger fractional anisotropy (FA) values in patients who recovered (SBPr) compared to those with persistent pain (SBPp), and predicted changes in pain severity. The SLF FA values accurately classified patients at baseline and follow-up in a third publicly available dataset (Area under the Receiver Operating Curve ~0.70). Notably, patients who recovered had FA values larger than those of HC suggesting a potential role of SLF integrity in resilience to CBP. Structural connectivity-based models also classified SBPp and SBPr patients from the three data sets (validation accuracy 67%). Our results validate the right SLF as a robust predictor of CBP development, with potential for clinical translation. Cognitive and behavioral processes dependent on the right SLF, such as proprioception and visuospatial attention, should be analyzed in subacute stages as they could prove important for back pain chronicity.

Deriving Mendelian Randomization-based Causal Networks of Brain Imaging Phenotypes and Bipolar Disorder.

Neuroanatomical variation in individuals with bipolar disorder (BD) has been previously described in observational studies. However, the causal dynamics of these relationships remain unexplored. We performed Mendelian Randomization of 297 structural and functional neuroimaging phenotypes from the UK BioBank and BD using genome-wide association study summary statistics. We found 28 significant causal relationship pairs after multiple testing corrections containing BD as a term, 27 of which described neuroimaging phenotype effects on BD. We applied an inverse sparse regression algorithm to estimate the direct effect of phenotypes conditional on all other causal effects, finding that white matter tract phenotypes have larger absolute effects on BD than vice versa. We found that white matter phenotypes have significantly larger out-degrees than non-white matter tract phenotypes, and that the effect of neuroimaging variation on BD is larger than vice versa. Our results provide support for the hypothesis that neuroanatomical variation, specifically in white matter tracts such as the superior and inferior longitudinal fasciculi, is a cause rather than a consequence of BD.

Fractional amplitude of low-frequency fluctuations in right dorsal cingulum bundle associated with depression symptoms in AD patients: effects of donepezil intervention.

Our aim was to investigate the mechanisms of spontaneous brain activity of white matter functional signals in Alzheimer's disease (AD) patients after donepezil intervention. We used resting-state functional magnetic resonance imaging and the fractional amplitude of low-frequency fluctuations (fALFF) approach to investigate changes in spontaneous brain activity of white matter functional signals in AD patients before and after donepezil intervention. A total of 32 subjects participated in the study, including 16 healthy subjects (HCs) and 16 AD patients. The 16 AD patients underwent brain imaging and neuropsychological assessment before and after donepezil. ANOVA and post hoc t-test analysis were used to compare the differences in fALFF between the three groups. Pearson correlations were used to investigate the relationships between abnormal fALFF values and clinical variables in AD patients before and after intervention (P < 0.05). Compared to HCs, AD patients before donepezil intervention had an abnormal fALFF in superior longitudinal fasciculus 2; AD patients after donepezil intervention had an abnormal fALFF in right superior longitudinal fasciculus 1,2 and right dorsal cingulum, Compared with baseline, AD patients after donepezil intervention had an abnormal fALFF in the right dorsal cingulum. Compared with the baseline, AD patients after donepezil intervention had significantly decreased depression scores (P < 0.0003). Our study showed that spontaneous activity of functional signalling in the cholinergic pathway was altered in AD patients after donepezil intervention and that this change was associated with depressive symptoms in AD patients.

White matter organization abnormalities in adults with 47,XXX: a 7 Tesla MRI study

47,XXX (Triple X syndrome) is a sex chromosome aneuploidy characterized by the presence of a supernumerary X chromosome in affected females, and has been associated with a variable cognitive, behavioral, and psychiatric phenotype. Alterations in brain gray matter structure and function have been reported, but less is known about white matter (WM) organization in 47,XXX. Therefore, we conducted 7 T diffusion tensor imaging and characterized fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity of 22 adult women with 47,XXX and 22 age-matched typically developing females using tract-based spatial statistics. Relationships between phenotypic traits and WM organization characteristics in 47,XXX were also investigated. Adults with 47,XXX showed lower axial diffusivity in the body of the corpus callosum and the right superior longitudinal fasciculus. WM organization variability was not associated with IQ and social cognition and social functioning deficits in 47,XXX. Our findings indicate an effect of a supernumerary X chromosome in adult women on axonal integrity of the body of the corpus callosum and the right superior longitudinal fasciculus. These findings provide additional insight into the role of the X chromosome on WM organization. Future research is warranted to explore the clinical significant impact of altered WM organization in 47,XXX.

Automated Fiber Quantification Analysis Identifies Tract-specific Microstructural Alterations in Brain in Intermittent exotropia

BackgroundGrowing evidence of neuroimaging has indicated brain microstructural abnormalities in comitant strabismus. Nonetheless, few studies have investigated neuropathological alterations in patients with intermittent exotropia (IXT). This study aimed at examining the characteristics of brain microstructure along major fiber tracts in IXT patients using an automated fiber quantification analysis. MethodsA total of 25 patients with IXT as well as 25 healthy participants matched for age and gender finished the diffusion tensor imaging scanning and the ophthalmic examination. Automated fiber quantification analysis of 20 major fiber tracts was carried out for IXT patients and healthy subjects, respectively. Diffusion metrics of 100 equidistant nodes resampled along each tract were measured for every subject and compared between two groups. Effect size analysis was performed to identify the most affected fiber tracts in IXT. ResultsWidely declined mean diffusivity was noted in IXT along major tracts containing bilateral thalamic radiations, bilateral corticospinal fasciculi, bilateral cingulum cingulate, left inferior fronto-occipital fasciculus, right arcuate fasciculus and superior longitudinal fasciculus. Local reduction in fractional anisotropy was observed in IXT along left cingulum hippocampus, right inferior longitudinal fasciculus and right uncinate fasciculus, in contrast to the regionally increased fractional anisotropy along bilateral thalamic radiation, left corticospinal tract and left arcuate fasciculus. Among the tracts with significantly changed diffusion metrics in IXT, right inferior longitudinal fasciculus was the most affected one in fractional anisotropy while left thalamic radiation was the most influenced one in mean diffusivity. ConclusionsAbnormalities in microstructural properties along visual-related fiber tracts are likely to contribute to difficulties in visual information processing in IXT patients, which could serve as the neural basis of underlying pathological mechanism of IXT.

Links between cognition and multivariate brain white matter differences in individuals with family history of Alzheimer's disease

AbstractBackgroundAlzheimer’s disease (AD) is thought to result from a complex cascade of events involving several pathological processes. Recent studies have reported alterations in white matter (WM) microstructure in the early phase of AD, but WM remains understudied. We used a multivariate approach to capture the complexity and heterogeneity of WM pathologies and its links to cognition and AD risk factors in a more holistic manner.MethodThe MRI data of 134 cognitively unimpaired older adults with a family history of AD from the PREVENT‐AD cohort were analysed. Diffusion‐weighted imaging and multi‐echo magnetization transfer, proton density and T1‐weighted data were used to compute several WM metrics (see Fig. 1b‐c). We used the Mahalanobis distance (D2) to summarize the MRI metrics into a single score, indicative of the degree a voxel’s microstructure differs relative to a reference. Voxel‐wise D2 was computed for each subject relative to the group average of all other subjects using the MVComp tool and D2 maps were residualized for age (Fig. 2). Partial Least Squares (PLS) analyses were then performed to relate WM D2 with cognition (RBANS) and AD risk factors, separately in each sex.ResultIn males, there was only one significant latent variable (LV 1). There were extensive brain WM regions associated with this LV pattern: higher white matter D2, was associated with higher BMI, lower total cholesterol (likely due to lower HDL) and worse cognitive performance in all cognitive domains except attention (Fig. 2a‐b). In females, only the first LV was significant. Higher D2 in several WM tracts, including the inferior and superior longitudinal fasciculus, and the parahippocampal cingulum, was associated with lower education, and worse cognitive performance in all cognitive domains except attention and visuospatial construction. Higher WM D2 was also associated with several metabolic risk factors in females including higher SBP, higher BMI, higher glycated hemoglobin (HbA1c) and lower cholesterol (Fig. 2c‐d).ConclusionThe different patterns of associations observed suggest there are sex‐specific risk profiles associated with WM microstructure differences in this population of older adults at risk of AD. The WM tracts affected in each sex were also associated with specific cognitive profiles.

Association between white matter microstructural changes and aggressiveness. A case-control diffusion tensor imaging study

Research has focused on identifying neurobiological risk factors associated with aggressive behavior in order to improve prevention and treatment efforts. This study aimed to characterize microstructural differences in white matter (WM) integrity in individuals prone to aggression. We hypothesized that altered cerebral WM microstructure may underlie normal individual variability in aggression and tested this using a case-control design in healthy individuals. Diffusion tensor imaging (DTI) was used to examine WM changes in martial artists (n = 29) and age-matched controls (n = 31). We performed tract-based spatial statistics (TBSS) to identify differences in axial diffusivity (AD), fractional anisotropy (FA) and mean diffusivity (MD) between the two groups at the whole-brain level. Martial artists were significantly more aggressive than controls, with increased MD in parietal and occipital areas and increased AD in widespread fiber tracts in the frontal, parietal and temporal areas. Positive associations between AD/MD and (physical) appetitive aggression were identified in several clusters, including the corpus callosum, the superior longitudinal fasciculus and the corona radiata. Our study found evidence for WM microstructural changes associated with aggressiveness in a community case-control sample. Longitudinal studies with larger cohorts, taking into account the dimensional nature of aggressiveness, are needed to better understand the underlying neurobiology.

Quantitative susceptibility mapping reveals brain iron accumulation in minimal hepatic encephalopathy: associations with neurocognitive changes.

Brain iron deposition is correlated with minimal hepatic encephalopathy (MHE). This study aimed to investigate the pattern of altered iron distribution, using quantitative susceptibility mapping (QSM), and to clarify the relationship between iron deposition and neurocognitive changes in MHE.We enrolled 32 cirrhotic patients without MHE (NHE), 21 cirrhotic patients with MHE, and 24 healthy controls, and used the Psychometric Hepatic Encephalopathy Score (PHES) to assess neurocognitive function. All participants underwent magnetic resonance scans with a gradient-echo sequence reconstructing for QSM. We performed voxel-wise and region-of-interest (ROI)-wise analyses to investigate the QSM difference across three groups and to examine the relationship between susceptibility value and PHES.MHE patients exhibited increased susceptibility value in widespread brain areas (family-wise error (FWE)-corrected P < 0.05), which was located mainly in cognition-related regions (such as the prefrontal lobe, precuneus, inferior parietal lobule, insula, thalamus, and superior longitudinal fasciculus), sensorimotor regions (such as the precentral/postcentral gyrus, superior parietal lobule, and posterior corona radiata), visual regions (such as the occipital cortex and posterior thalamic radiation), and auditory regions (such as the temporal lobe). NHE patients also followed a trend of increasing susceptibility in the scattered brain regions, but which did not reach statistical significance (FWE-corrected P > 0.05). We observed negative correlations between cirrhotic patients' PHES and regional susceptibility values (FWE-corrected P < 0.05).Brain iron accumulation (measured using QSM) contributes to cognitive impairments in MHE patients. QSM could provide new insights into the pathogenesis of MHE and facilitate monitoring disease development.

Exploring Tractography: An Analysis of Brain Connectivity Patterns in Men.

White matter tracts that connect different parts of the brain comprise the structural connectome, which is essential to its operation. Assessing behavioral changes and brain health requires an understanding of these tracts. Diffusion tensor imaging (DTI), in particular, allows for the thorough viewing and characterization of these routes in tractography. In order to assess the impact of aging on white matter integrity, this study examines the 10 main white matter tracts in men, paying particular attention to volume, fractional anisotropy (FA), and mean diffusivity (MD). A cohort of 49 menaged 18-50 years was examined using a Philips Multiva 1.5T MRI. DTI scans were performed after obtaining informed consent. Participants with neuronal disorders were excluded. Ten tracts were assessed: inferior fronto-occipital fasciculus (IFOF), superior fronto-occipital fasciculus (SFOF), inferior longitudinal fasciculus (ILF), superior longitudinal fasciculus (SLF), cingulum, corticospinal tract (CST), forceps major, forceps minor, uncinate fasciculus, and anterior thalamic radiation (ATR). Statistical analysis employed Kruskal-Wallis tests to compare age groups. Significant age-related differences were observed in the IFOF, which exhibited notable changes in both volume and MD. Specifically, the IFOF's volume peaked in the 31-40 age group (14.42 ± 6.05) and declined in the 41-50 age group (8.71 ± 5.07), with a statistically significant p-value of 0.019. In parallel, MD increased significantly with age, moving from 0.86 ± 0.08 in the 18-30 group to 1.09 ± 0.13 in the 31-40 group and stabilizing at 0.96 ± 0.12 in the 41-50 group (p < 0.001). Notably, while the FA values remained relatively stable across age groups (p = 0.063), the increase in MD suggests a decline in neural efficiency or potential myelin degradation. Other tracts, including the SFOF and SLF, displayed stability in volume, FA, and MD across age groups, indicating a degree of resilience in certain neural pathways. This study highlights the utility of tractography in understanding age-related changes in white matter, such as in Alzheimer's disease, age- and sex-related abnormalities, and dementia, particularly emphasizing the IFOF's sensitivity. Findings offer insights into brain connectivity and neurological health, indicating a need for further contribution to inform interventions aimed at cognitive preservation.

Transdiagnostic alterations in white matter microstructure associated with suicidal thoughts and behaviours in the ENIGMA Suicidal Thoughts and Behaviours consortium.

Previous studies have suggested that alterations in white matter (WM) microstructure are implicated in suicidal thoughts and behaviours (STBs). However, findings of diffusion tensor imaging (DTI) studies have been inconsistent. In this large-scale mega-analysis conducted by the ENIGMA Suicidal Thoughts and Behaviours (ENIGMA-STB) consortium, we examined WM alterations associated with STBs. Data processing was standardised across sites, and resulting WM microstructure measures (fractional anisotropy, axial diffusivity, mean diffusivity and radial diffusivity) for 25 WM tracts were pooled across 40 cohorts. We compared these measures among individuals with a psychiatric diagnosis and lifetime history of suicide attempt ( n =652; mean age=35.4±14.7; female=71.8%), individuals with a psychiatric diagnosis but no STB (i.e., clinical controls; n =1871; mean age=34±14.8; female=59.8%), and individuals with no mental disorder diagnosis and no STB (i.e., healthy controls; n =642; mean age=29.6±13.1; female=62.9%). We also compared these measures among individuals with recent suicidal ideation ( n =714; mean age=36.3±15.3; female=66.1%), clinical controls ( n =1184; mean age=36.8±15.6; female=63.1%), and healthy controls ( n =1240; mean age= 31.6±15.5; female=61.0%). We found subtle but statistically significant effects, such as lower fractional anisotropy associated with a history of suicide attempt, over and above the effect of psychiatric diagnoses. These effects were strongest in the corona radiata, thalamic radiation, fornix/stria terminalis, corpus callosum and superior longitudinal fasciculus. Effect sizes were small (Cohen's d < 0.25). Recent suicidal ideation was not associated with alterations in WM microstructure. This large-scale coordinated mega-analysis revealed subtle regional and global alterations in WM microstructure in individuals with a history of suicide attempt. Longitudinal studies are needed to confirm whether these alterations are a risk factor for suicidal behaviour.

Asymmetry of attentive networks contributes to adult Attention-deficit/hyperactivity disorder (ADHD) pathophysiology.

Diffusion imaging studies in Attention-deficit/hyperactivity disorder (ADHD) have revealed alterations in anatomical brain connections, such as the fronto-parietal connection known as superior longitudinal fasciculus (SLF). Studies in neurotypical adults have shown that the three SLF branches (SLF I, II, III) support distinct brain functions, such as attention and inhibition; and that their pattern of lateralization is associated with attention performance. However, most studies in ADHD have investigated the SLF as a single bundle and in children; thus, the potential contribution of the lateralization of the SLF branches to adult ADHD pathophysiology remains to be elucidated. We used diffusion-weighted spherical deconvolution tractography to dissect the SLF branches in 60 adults with ADHD (including 26 responders and 34 non-responders to methylphenidate, MPH) and 20 controls. Volume and hindrance modulated orientational anisotropy (HMOA), which respectively reflect white matter macro- and microstructure, were extracted to calculate the corresponding lateralization indices. We tested whether neurotypical controls differed from adults with ADHD, and from treatment response groups in sensitivity analyses; and investigated associations with clinico-neuropsychological profiles. All the three SLF branches were lateralized in adults with ADHD, but not in controls. The lateralization of theSLFI HMOA was associated with performance at the line bisection, not that of the SLF II volume as previously reported in controls. Further, an increased left-lateralization of the SLF I HMOA was associated with higher hyperactivity levels in the ADHD group. Thus, an altered asymmetry of the SLF, perhaps especially of the dorsal branch, may contribute to adult ADHD pathophysiology.

White Matter Function and Network Abnormalities in Patients with Diabetic Retinopathy.

This study aims to explore changes in white matter function and network connectivity in individuals with DR. This study included 46 patients with DR and 43 age- and gender-matched healthy control (HC) participants were enrolled in the study. The aim was to investigate inter-group differences in white matter (WM) function and to analyze changes in the WM network among DR patients. Increased degree centrality (DC) values were observed in the middle cerebellar peduncle and genu of the corpus callosum, while higher fractional amplitude of low-frequency fluctuations (fALFF) values were found in the left superior corona radiata, right anterior corona radiata, and right superior longitudinal fasciculus. Conversely, reduced regional homogeneity (ReHo) values were noted in the left posterior thalamic radiation among patients with DR compared to HC, with statistical correction applied The SVM classification accuracy for distinguishing between DR and HC patients based on WM measures indicated values of 81.52%, 80.43%, and 89.13% for DC, fALFF, and ReHo, respectively, with respective area under the curve (AUC) values of 0.87, 0.85, and 0.93. Furthermore, alterations were detected within specific brain regions including the body of corpus callosum (BCC), splenium of corpus callosum (SCC), genu of corpus callosum (GCC), left posterior thalamic radiation (PTR), right anterior corona radiata (ACR), and right posterior corona radiata (PCR) in the DR group compared to HCs, with an intra-network decrease in connectivity. Interestingly, the left superior longitudinal fasciculus (SLF) within the DR group exhibited an intra-network increase compared to the HC group. DR exhibited abnormal white matter functional alterations, particularly affecting the fiber pathways linking the visual network to the sensory-motor network.