Superior Fronto-occipital Fasciculus Research Articles

Causal relationship between multiparameter brain MRI phenotypes and age: evidence from Mendelian randomization.

To explore the causal relationship between age and brain health (cortical atrophy, white matter integrity, white matter hyperintensities and cerebral microbleeds in various brain regions) related multiparameter imaging features using two-sample Mendelian randomization. Age was determined as chronological age of the subject. Cortical volume, white matter micro-integrity, white matter hyperintensity volume and cerebral microbleeds of each brain region were included as phenotypes for brain health. Age and imaging of brain health related genetic data were analysed to determine the causal relationship using inverse-variance weighted model, validated by heterogeneity and horizontal pleiotropy variables. Age is causally related to increased volumes of white matter hyperintensities (β = 0.151). For white matter micro-integrity, fibres of the inferior cerebellar peduncle (axial diffusivity β = -0.128, orientation dispersion index β = 0.173), cerebral peduncle (axial diffusivity β = -0.136), superior fronto-occipital fasciculus (isotropic volume fraction β = 0.163) and fibres within the limbic system were causally deteriorated. We also detected decreased cortical thickness of multiple frontal and temporal regions (P < 0.05). Microbleeds were not related with aging (P > 0.05). Aging is a threat of brain health, leading to cortical atrophy mainly in the frontal lobes, as well as the white matter degeneration especially abnormal hyperintensity and deteriorated white matter integrity around the hippocampus.

Distinguishing schizophrenia and bipolar disorder through a Multiclass Classification model based on multimodal neuroimaging data

This study aimed to identify neural biomarkers for schizophrenia (SZ) and bipolar disorder (BP) by analyzing multimodal neuroimaging. Utilizing data from structural magnetic resonance imaging (sMRI), diffusion tensor imaging (DTI), and resting-state functional magnetic resonance imaging (rs-fMRI), multiclass classification models were created for SZ, BP, and healthy controls (HC). A total of 113 participants (BP: 31, SZ: 39, and HC: 43) were recruited under strict enrollment control, from which 272, 200, and 1875 features were extracted from sMRI, DTI, and rs-fMRI data, respectively. A support vector machine (SVM) with recursive feature elimination (RFE) was employed to build the models using a one-against-one approach and leave-one-out cross-validation, achieving a classification accuracy of 70.8%. The most discriminative features were primarily from rs-fMRI, along with significant findings in sMRI and DTI. Key biomarkers identified included the increased thickness of the left cuneus cortex and decreased regional functional connectivity strength (rFCS) in the left supramarginal gyrus as shared indicators for BP and SZ. Additionally, decreased fractional anisotropy in the left superior fronto-occipital fasciculus was suggested as specific to BP, while decreased rFCS in the left inferior parietal area might serve as a specific biomarker for SZ. These findings underscore the potential of multimodal neuroimaging in distinguishing between BP and SZ and contribute to the understanding of their neural underpinnings.

Based on white matter microstructure to early identify bipolar disorder from patients with depressive episode

ObjectiveBecause of similar clinical manifestations, bipolar disorder (BD) patients are often misdiagnosed as major depressive disorder (MDD). This study aimed to compare the difference between depressed patients later converting to BD and unipolar depression (UD) according to diffusion tensor imaging (DTI). MethodPatients with MDD (562 participants) in depressive episode states and healthy controls (HCs) (145 participants) were recruited over 10 years. Demographic and magnetic resonance imaging (MRI) data were collected at the time of recruitment. All patients with MDD were followed up for 5 years and classified into the transfer to BD (tBD) group (83 participants) and UD group (160 participants) according to the follow-up results. DTI and functional magnetic resonance imaging at baseline were compared. ResultsCommon abnormalities were found in both tBD and UD groups, including left superior cerebellar peduncle (SCP.L), right anterior limb of the internal capsule (ALIC.R), right superior fronto-occipital fasciculus (SFOF.R), and right inferior fronto-occipital fasciculus (IFOF.R). The tBD showed more extensive abnormalities than the UD in the body of corpus callosum, fornix, left superior corona radiata, left posterior corona radiata, left superior longitudinal fasciculus, and left superior fronto-occipital fasciculus. ConclusionThe study demonstrated the common and distinct abnormalities of tBD and UD when compared to HC. The tBD group showed more extensive disruptions of white matter integrity, which could be a potential biomarker for the early identification of BD.

The interaction effects of age, APOE and common environmental risk factors on human brain structure.

Mounting evidence suggests considerable diversity in brain aging trajectories, primarily arising from the complex interplay between age, genetic, and environmental risk factors, leading to distinct patterns of micro- and macro-cerebral aging. The underlying mechanisms of such effects still remain unclear. We conducted a comprehensive association analysis between cerebral structural measures and prevalent risk factors, using data from 36,969 UK Biobank subjects aged 44-81. Participants were assessed for brain volume, white matter diffusivity, Apolipoprotein E (APOE) genotypes, polygenic risk scores, lifestyles, and socioeconomic status. We examined genetic and environmental effects and their interactions with age and sex, and identified 726 signals, with education, alcohol, and smoking affecting most brain regions. Our analysis revealed negative age-APOE-ε4 and positive age-APOE-ε2 interaction effects, respectively, especially in females on the volume of amygdala, positive age-sex-APOE-ε4 interaction on the cerebellar volume, positive age-excessive-alcohol interaction effect on the mean diffusivity of the splenium of the corpus callosum, positive age-healthy-diet interaction effect on the paracentral volume, and negative APOE-ε4-moderate-alcohol interaction effects on the axial diffusivity of the superior fronto-occipital fasciculus. These findings highlight the need of considering age, sex, genetic, and environmental joint effects in elucidating normal or abnormal brain aging.

The Influence of Prior Head Injury on Late‐Life Cognition and White Matter Microstructure in Older Adults At‐Risk of Alzheimer’s disease

AbstractBackgroundThe long‐term combined effects of mild traumatic brain injury (mTBI) and APOE ε4‐allele carrier status (APOE+/‐), a genetic risk factor of Alzheimer’s disease (AD), on cognition and white matter structural integrity in older adults at‐risk of AD is not fully understood.MethodTo investigate mTBI effects on late‐life neurobehavioural outcomes, a subsample of the PREVENT‐AD cohort was analyzed. Participants were cognitively normal adults over age 55 with a parental or multiple‐sibling history of AD. The mTBI group included individuals who self‐reported at least one prior mTBI with loss of consciousness and/or memory gap (n = 48, 33.3% APOE4+). Rey Auditory Verbal Learning Test measured immediate and delayed memory, Color‐Word Interference Test measured cognitive flexibility and inhibitory control, and Trail Making Test measured processing speed and attention.The control group included demographically‐matched (age, sex, years of education) participants from the same cohort without self‐reported mTBI (n = 62, 29.0% APOE4+). Data were analyzed using 2‐way ANOVAs with weighted means on years of education, corrected for multiple comparisons. To evaluate underlying structural differences in white matter tracts between mTBI and control groups, diffusion tensor imaging (DTI) metrics, including fractional anisotropy, axial and radial diffusivity, using the JHU‐atlas parcellation.ResultsmTBI/APOE4+ individuals performed significantly worse on cognitive outcomes of delayed recall, cognitive flexibility, and inhibitory control compared to controls; however, they performed significantly better on tests of processing speed and visual attention compared to mTBI/APOE4‐ individuals. DTI results showed that the mTBI group, compared to the control group, had significantly decreased axial diffusivity in the left internal capsule, right superior longitudinal fasciculus, and superior frontooccipital fasciculus (SFOF) (p&lt;0.05 uncorrected). Within the mTBI group, significant positive correlation between lower processing speed and decreased axial diffusivity of SFOF, accounting for age and sex.ConclusionOur findings suggest that prior mTBI impacts cognitive aging in older adults at‐risk of AD differentially depend on APOE4 status, where APOE4+ individuals with prior mTBI had worse working memory, cognitive flexibility, and inhibitory control but better processing speed outcomes. Lower cognitive outcomes in mTBI individuals may be supported by decreased diffusivity in specific white matter tracts. These results can inform dementia prevention in these individuals.

The Influence of Prior Head Injury on Late‐Life Cognition and White Matter Microstructure in Older Adults At‐Risk of Alzheimer’s disease

AbstractBackgroundThe long‐term combined effects of mild traumatic brain injury (mTBI) and APOE e4‐allele carrier status (APOE+/‐), a genetic risk factor of Alzheimer’s disease (AD), on cognition and white matter structural integrity in older adults at‐risk of AD is not fully understood.MethodTo investigate mTBI effects on late‐life neurobehavioural outcomes, a subsample of the PREVENT‐AD cohort was analyzed. Participants were cognitively normal adults over age 55 with a parental or multiple‐sibling history of AD. The mTBI group included individuals who self‐reported at least one prior mTBI with loss of consciousness and/or memory gap (n = 48, 33.3% APOE4+). Rey Auditory Verbal Learning Test measured immediate and delayed memory, Color‐Word Interference Test measured cognitive flexibility and inhibitory control, and Trail Making Test measured processing speed and attention. The control group included demographically‐matched (age, sex, years of education) participants from the same cohort without self‐reported mTBI (n = 62, 29.0% APOE4+). Data were analyzed using 2‐way ANOVAs with weighted means on years of education, corrected for multiple comparisons. To evaluate underlying structural differences in white matter tracts between mTBI and control groups, diffusion tensor imaging (DTI) metrics, including fractional anisotropy, axial and radial diffusivity, using the JHU‐atlas parcellation.ResultmTBI/APOE4+ individuals performed significantly worse on cognitive outcomes of delayed recall, cognitive flexibility, and inhibitory control compared to controls; however, they performed significantly better on tests of processing speed and visual attention compared to mTBI/APOE4‐ individuals. DTI results showed that the mTBI group, compared to the control group, had significantly decreased axial diffusivity in the left internal capsule, right superior longitudinal fasciculus, and superior frontooccipital fasciculus (SFOF) (p&lt;0.05 uncorrected). Within the mTBI group, significant positive correlation between lower processing speed and decreased axial diffusivity of SFOF, accounting for age and sex.ConclusionOur findings suggest that prior mTBI impacts cognitive aging in older adults at‐risk of AD differentially depend on APOE4 status, where APOE4+ individuals with prior mTBI had worse working memory, cognitive flexibility, and inhibitory control but better processing speed outcomes. Lower cognitive outcomes in mTBI individuals may be supported by decreased diffusivity in specific white matter tracts. These results can inform dementia prevention in these individuals.

Mendelian randomization analysis implicates bidirectional associations between brain imaging-derived phenotypes and ischemic stroke.

Brian imaging-derived phenotypes (IDPs) have been suggested to be associated with ischemic stroke, but the causality between them remains unclear. In this bidirectional two-sample Mendelian randomization (MR) study, we explored the potential causal relationship between 461 imaging-derived phenotypes (n = 33,224, UK Biobank) and ischemic stroke (n = 34,217 cases/406,111 controls, Multiancestry Genome-Wide Association Study of Stroke). Forward MR analyses identified five IDPs associated with ischemic stroke, including mean diffusivity (MD) in the right superior fronto-occipital fasciculus (1.22 [95% CI, 1.11-1.34]), MD in the left superior fronto-occipital fasciculus (1.30 [1.17-1.44]), MD in the anterior limb of the right internal capsule (1.36 [1.22-1.51]), MD in the right anterior thalamic radiation (1.17 [1.09-1.26]), and MD in the right superior thalamic radiation (1.23 [1.11-1.35]). In the reverse MR analyses, ischemic stroke was identified to be associated with three IDPs, including high isotropic or free water volume fraction in the body of corpus callosum (beta, 0.189 [95% confidence interval, 0.107-0.271]), orientation dispersion index in the pontine crossing tract (0.175 [0.093-0.257]), and volume of the third ventricle (0.219 [0.138-0.301]). This bidirectional two-sample MR study suggested five predictors and three diagnostic markers for ischemic stroke at the brain-imaging level. Further studies are warranted to replicate our findings and clarify underlying mechanisms.

More extensive structural damage in temporal lobe epilepsy with hippocampal sclerosis type 1

ObjectiveTo explore clinical and structural differences between mesial temporal lobe epilepsy (mTLE) patients with different hippocampal sclerosis (HS) subtypes. MethodsHigh-resolution T1-weighted MRI and diffusion tensor imaging data were obtained in 41 refractory mTLE patients and 52 age- and sex-matched healthy controls. Postoperative histopathological examination confirmed HS type 1 in 30 patients and HS type 2 in eleven patients. Clinical features, postoperative seizure outcomes, hippocampal subfields volumes, fractional anisotropy (FA) values of white matter regions and graph theory parameters were explored and compared between the HS type 1 and HS type 2 groups. ResultsNo significant differences in clinical features and postsurgical seizure outcomes were found between the HS type 1 and type 2 groups. However, the HS type 1 group showed extra atrophy in ipsilateral parasubiculum than healthy controls and more severe atrophy in contralateral hippocampal fissure than the HS type 2 group. More extensive FA decrease were also observed in the HS type 1 group, involving ipsilateral optic radiation, superior fronto-occipital fasciculus, contralateral uncinate fasciculus, tapetum, bilateral hippocampal cingulum, corona radiata, etc. Furthermore, in spite of similar impairments in characteristic path length, global efficiency and local efficiency in two HS groups, the HS type 1 group showed additional decrease of clustering coefficient than healthy controls. ConclusionsHS type 1 and 2 groups had similar clinical characteristics and postoperative seizure outcomes. More widespread neuronal cell loss in the HS type 1 group contributed to more extensive structural damage and connectivity abnormality. These results shed new light on the imaging correlates of different HS pathology.

Study of the relationship between onset lateralization and hemispheric white matter asymmetry in Parkinson's disease.

Parkinson's disease (PD) is characterized by a lateralized onset, but its cause and mechanism are still unclear. Obtaining diffusion tensor imaging (DTI) data from the Parkinson's Progression Markers Initiative (PPMI). Tract-based spatial statistics analysis and region-of-interest-based analysis were performed to evaluate the white matter (WM) asymmetry using original DTI parameters, Z Score normalized parameters, or the asymmetry index (AI). Hierarchical cluster analysis and least absolute shrinkage and selection operator regression were performed to construct predictive models for predicting the PD onset side. DTI data from The Second Affiliated Hospital of Chongqing Medical University were obtained for external validation of the prediction model. 118 PD patients and 69 healthy controls (HC) from PPMI were included. Right-onset PD patients presented more asymmetric areas than left-onset PD patients. The inferior cerebellar peduncle (ICP), superior cerebellar peduncle (SCP), external capsule (EC), cingulate gyrus (CG), superior fronto-occipital fasciculus (SFO), uncinate fasciculus (UNC), and tapetum (TAP) showed significant asymmetry inleft-onset and right-onset PD patients. An onset-side-specific pattern of WM alterations exists in PD patients, and a prediction model was constructed. The predicting models based on AI and ΔZ Score presented favorable efficacy in predicting PD onset side by external validation in 26 PD patients and 16 HCs from our hospital. Right-onset PD patients may have more severe WM damage than left-onset PD patients. WM asymmetry in ICP, SCP, EC, CG, SFO, UNC, and TAP may predict PD onset side. Imbalances in the WM network may underlie the mechanism of lateralized onset in PD.

Associations between Aortic Stiffness, Cerebral Artery Resistance and White Matter Integrity in Women with a History of Preeclampsia

Purpose: Preeclampsia is a pregnancy complication characterized by new-onset hypertension and systemic organ dysfunction. Women with a history of preeclampsia (hxPE) have a greater cerebral white matter ischemic damage burden and a three-fold elevated risk of vascular dementia later in life compared with healthy pregnancy independent of traditional cardiovascular risk factors. Aortic stiffness promotes the transmission of deleterious pulsatile pressure to the distal cerebral circulation, resulting in increased cerebrovascular resistance (CVR) that contributes to compromised brain blood flow and structure. We hypothesized that young women with hxPE would have greater aortic stiffness and CVR compared to healthy pregnancy, and CVR would be related to lower cerebral white matter microstructural integrity (WMI). Methods: Women with hxPE (N=10) were matched with healthy pregnancy controls (N=11) by age (28-42 years), educational attainment, body mass index, and postpartum duration (1-5 years). Aortic stiffness was quantified as carotid-femoral pulse wave velocity (CFPWV). 4D flow and diffusion tensor magnetic resonance images were acquired to evaluate internal carotid and middle cerebral artery (MCA) blood flow velocity and WMI (fractional anisotropy), respectively (3T MRI, GE). CVR index was calculated as the ratio of central mean arterial pressure to regional flow velocity. Results: Women with hxPE tended to exhibit higher CFPWV compared with controls (6.3±0.8 vs 5.6±0.7 m/s, P=0.09 adjusted for mean arterial pressure). CVR did not differ at the internal carotid artery (2.2±0.4 vs 2.0±0.3 mmHg s cm -1 , P=0.30) but was higher at the MCA among women with hxPE (2.4±0.3 vs 2.1±0.4 mmHg s cm -1 , P=0.08). In the entire group, CFPWV was associated with greater CVR at the internal carotid (r=0.41, P=0.07) and MCA (r=0.48, P=0.03). Although WMI did not differ between groups, greater MCA CVR was related to lower WMI overall (r=-0.45, P=0.049) and in select white matter tracts (corpus callosum genu, r=-0.53, P=0.02; cingulum hippocampus, r=-0.43, P=0.06; superior frontooccipital fasciculus, r=-0.46, P=0.04). Conclusions: Women with hxPE had elevated aortic stiffness that was associated with greater CVR. Greater CVR was related to lower WMI in subcortical watershed regions susceptible to reduced perfusion. These findings indicate that aortic stiffness may contribute to early declines in WMI via CVR in women with hxPE. Supported by AHA Transformational Project Award (969732) to GLP and NIH grant 1S10OD025025-01 to VM This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Visual networks: Electric brain stimulation and diffusion tensor imaging

ObjectiveThe present study investigated the networks of visual functional areas using electric brain stimulation (EBS) and diffusion tensor imaging (DTI). MethodsThirteen patients with intractable focal epilepsy in which visual functional areas were identified by EBS were enrolled. An electric stimulation at 50Hz was applied to electrodes during several tasks. DTI was used to identify subcortical fibers originating from the visual functional areas identified by EBS. ResultThe electrical stimulation induced three types of visual symptoms: visual illusions (change of vision), visual hallucinations (appearance of a new object), and blurred vision. Visual illusions were associated with stimulation of lateral temporo-parieto-occipital areas, and visual hallucinations with stimulation of lateral/basal temporal areas, the occipital lobe and the precuneus. Stimulus intensities eliciting visual illusions were significantly higher than those for visual hallucinations. Tractography revealed that the superior fronto-occipital fasciculus was associated with visual illusions and the middle longitudinal fasciculus with visual hallucinations, and both symptoms shared several subcortical fibers such as the vertical occipital fasciculus, inferior fronto-occipital fasciculus, superior longitudinal fasciculus, inferior longitudinal fasciculus, optic radiations, and commissural fibers. ConclusionThe present study revealed the characteristic cortical regions and networks of visual functional areas. The results obtained provide information on human visual functions and are a practical guide for electrical cortical stimulation.

Lower Myelin Content Is Associated With Lower Gait Speed in Cognitively Unimpaired Adults.

Mounting evidence indicates that abnormal gait speed predicts the progression of neurodegenerative diseases, including Alzheimer's disease. Understanding the relationship between white matter integrity, especially myelination, and motor function is crucial to the diagnosis and treatment of neurodegenerative diseases. We recruited 118 cognitively unimpaired adults across an extended age range of 22-94 years to examine associations between rapid or usual gait speeds and cerebral myelin content. Using our advanced multicomponent magnetic resonance relaxometry method, we measured myelin water fraction (MWF), a direct measure of myelin content, as well as longitudinal and transverse relaxation rates (R1 and R2), sensitive but nonspecific magnetic resonance imaging measures of myelin content. After adjusting for covariates and excluding 22 data sets due to cognitive impairments or artifacts, our results indicate that participants with higher rapid gait speed exhibited higher MWF, R1, and R2 values, that is, higher myelin content. These associations were statistically significant within several white matter brain regions, particularly the frontal and parietal lobes, splenium, anterior corona radiata, and superior fronto-occipital and longitudinal fasciculus. In contrast, we did not find any significant associations between usual gait speed and MWF, R1, or R2, which suggests that rapid gait speed may be a more sensitive marker of demyelination than usual gait speed. These findings advance our understanding on the implication of myelination in gait impairment among cognitively unimpaired adults, providing further evidence of the interconnection between white matter integrity and motor function.

White and gray matter alterations in de novo PD patients: which matter most?

This paper aimed to identify white matter (WM) and gray matter (GM) abnormalities in a sample of early PD patients, and their correlations with motor and non-motor symptom severity. We enrolled 62 de novo PD patients and 31 healthy subjects. Disease severity and non-motor symptom burden were assessed by the Unified Parkinson's Disease Rating Scale part III and the Non-Motor Symptoms Scale, respectively. Cognitive performance was assessed using Montreal Cognitive Assessment and Frontal Assessment Battery. All subjects underwent a 3-Tesla MRI protocol. MRI analyses included tract-based spatial statistics, cortical thickness, and subcortical and cerebellar volumetry. In comparison to control subjects, PD patients exhibited lower fractional anisotropy and higher mean, axial, and radial diffusivity in most WM bundles, including corticospinal tracts, the internal and external capsule, the anterior and posterior thalamic radiations, the genu and body of the corpus callosum, cerebellar peduncles, and superior and inferior longitudinal and fronto-occipital fasciculi. Correlations between Montreal Cognitive Assessment scores and fractional anisotropy values in the right posterior thalamic radiation, left superior corona radiata, right inferior-fronto-occipital fasciculus, left inferior longitudinal fasciculus, bilateral anterior thalamic radiations, and bilateral superior longitudinal fasciculi were found. Smaller cerebellar volumes in early PD patients in the left and right crus I were also found. No GM changes were present in subcortical or cortical regions. The combined evaluation of WM and GM in the same patient sample demonstrates that WM microstructural abnormalities precede GM structural changes in early PD patients.

White matter connectivity in resilience in a general population sample of 12,516 individuals

Neurobiological correlates of resilience to stress or trauma have not been investigated extensively. Studies on white matter connectivity in resilience, in particular, have been few and far between. This explorative study included 12,516 participants from the UK Biobank to investigate white matter connectivity in resilience in 13 selected regions of interest (ROIs). The data for this cross-sectional cohort study were retrieved from UK Biobank, a large-scale biomedical database and research resource. The study included 40-69-year-old women and men, as enrolled by UK Biobank, (N ​= ​12,516) divided into three groups: a trauma-exposed, healthy (resilient) group, a trauma-exposed, mentally ill (vulnerable) group and a nonexposed, healthy (control) group. The primary outcome measures consisted of mean fractional anisotropy values in the following ROIs: cingulate gyrus, cingulum hippocampus, superior fronto-occipital fasciculus, uncinate fasciculus, corpus callosum body, genu, splenium, and tapetum. Group differences in fractional anisotropy were assessed using a one-way analysis of variance. This study did not find correlates of resilience in the investigated ROIs. The results indicate that there is no association between resilience and white matter connectivity in the selected ROIs in this large population sample, which is in contrast with previous studies on morphometric and functional correlates of resilience. To corroborate this finding, the authors recommend collection of longitudinal data and utilization of voxelwise analysis, if possible, to improve sensitivity. The authors also suggest a whole-brain analysis in a similar study population to investigate other white matter tracts that might be implicated in resilience.

Brain grey and white matter structural associations with future suicidal ideation and behaviors in adolescent and young adult females with mood disorders.

To reduce suicide in females with mood disorders, it is critical to understand brain substrates underlying their vulnerability to future suicidal ideation and behaviors (SIBs) in adolescence and young adulthood. In an international collaboration, grey and white matter structure was investigated in adolescent and young adult females with future suicidal behaviors (fSB) and ideation (fSI), and without SIBs (fnonSIB). Structural (n = 91) and diffusion-weighted (n = 88) magnetic resonance imaging scans at baseline and SIB measures at follow-up on average two years later (standard deviation, SD = 1 year) were assessed in 92 females [age(SD) = 16.1(2.6) years] with bipolar disorder (BD, 28.3%) or major depressive disorder (MDD, 71.7%). One-way analyses of covariance comparing baseline regional grey matter cortical surface area, thickness, subcortical grey volumes, or white matter tensor-based fractional anisotropy across fSB (n = 40, 43.5%), fSI (n = 33, 35.9%) and fnonSIB (n = 19, 20.6%) groups were followed by pairwise comparisons in significant regions (p < 0.05). Compared to fnonSIBs, fSIs and fSBs showed significant decreases in cortical thickness of right inferior frontal gyrus pars orbitalis and middle temporal gyrus, fSIs of left inferior frontal gyrus, pars orbitalis. FSIs and fSBs showed lower fractional anisotropy in left uncinate fasciculus and corona radiata, and fSBs in right uncinate and superior fronto-occipital fasciculi. The study provides preliminary evidence of grey and white matter alterations in brain regions subserving emotional and behavioral regulation and perceptual processing in adolescent and young adult females with mood disorders with, versus without, future SIBs. Findings suggest potential targets to prevent SIBs in female adolescents and young adults.

Effects of Arterial Stiffness on Cerebral WM Integrity in Older Adults: A Neurite Orientation Dispersion and Density Imaging and Magnetization Transfer Saturation Imaging Study.

Arterial stiffness is reported to be able to cause axonal demyelination or degeneration. The present study aimed to use advanced MR imaging techniques to examine the effect of arterial stiffness on the WM microstructure among older adults. Arterial stiffness was measured using the cardio-ankle vascular elasticity index (CAVI). The high-CAVI (mean CAVI ≥ 9 points) and the low-CAVI groups (mean CAVI < 9 points) were created. The neuronal fiber integrity of the WM was evaluated by neurite orientation dispersion and density imaging and magnetization transfer saturation imaging. Tract-Based Spatial Statistics and the tracts-of-interest analysis were performed. Specific WM regions (corpus callosum, internal capsule, anterior thalamic radiation, corona radiata, superior longitudinal fasciculus, forceps minor, and inferior fronto-occipital fasciculus) were selected in the tracts-of-interest analysis. In Tract-Based Spatial Statistics, the high-CAVI group showed a significantly lower myelin volume fraction value in the broad WM and significantly higher radial diffusivity and isotropic volume fraction values in the corpus callosum, forceps minor, inferior fronto-occipital fasciculus, internal capsule, corona radiata, and anterior thalamic radiation than the low-CAVI group. In tracts-of-interest analysis using multivariate linear regression, significant associations were found between the mean CAVI and radial diffusivity in the anterior thalamic radiation and the corona radiata; isotropic volume fraction in the anterior thalamic radiation and the corona radiata; and myelin volume fraction in the superior longitudinal fasciculus (P < .05). Additionally, partial correlation coefficients were observed for the significant associations of executive function with radial diffusivity and myelin volume fraction (P < .05). Arterial stiffness could be associated with demyelination rather than axonal degeneration.

Disruption of white matter integrity and its relationship with cognitive function in non-severe traumatic brain injury.

BackgroundImpairment in cognitive function is a recognized outcome of traumatic brain injury (TBI). However, the degree of impairment has variable relationship with TBI severity and time post injury. The underlying pathology is often due to diffuse axonal injury that has been found even in mild TBI. In this study, we examine the state of white matter putative connectivity in patients with non-severe TBI in the subacute phase, i.e., within 10 weeks of injury and determine its relationship with neuropsychological scores.MethodsWe conducted a case-control prospective study involving 11 male adult patients with non-severe TBI and an age-matched control group of 11 adult male volunteers. Diffusion MRI scanning and neuropsychological tests were administered within 10 weeks post injury. The difference in fractional anisotropy (FA) values between the patient and control groups was examined using tract-based spatial statistics. The FA values that were significantly different between patients and controls were then correlated with neuropsychological tests in the patient group.ResultsSeveral clusters with peak voxels of significant FA reductions (p < 0.05) in the white matter skeleton were seen in patients compared to the control group. These clusters were located in the superior fronto-occipital fasciculus, superior longitudinal fasciculus, uncinate fasciculus, and cingulum, as well as white matter fibers in the area of genu of corpus callosum, anterior corona radiata, superior corona radiata, anterior thalamic radiation and part of inferior frontal gyrus. Mean global FA magnitude correlated significantly with MAVLT immediate recall scores while matrix reasoning scores correlated positively with FA values in the area of right superior fronto-occipital fasciculus and left anterior corona radiata.ConclusionThe non-severe TBI patients had abnormally reduced FA values in multiple regions compared to controls that correlated with several measures of executive function during the sub-acute phase of TBI.

Alterations in resting-state functional connectivity associated to the age-related decline in time-based prospective memory.

Time-based prospective memory (TBPM) is defined as the ability to remember to perform intended actions at a specific time in the future. TBPM is impaired in aging, and this decline has been associated with white-matter alterations within the superior fronto-occipital fasciculus. In the present study, we used resting-state functional magnetic resonance imaging from 22 healthy young (26 ± 5.2years) and 23 older (63 ± 6.1years) participants to investigate how age-related alterations in resting-state functional connectivity are related to TBPM performance, and whether these alterations are associated with the white-matter disruptions we have previously observed with diffusion tensor imaging. Whole-brain analyses revealed lower resting-state functional connectivity in older participants compared with younger ones, which in turn correlated with TBPM performance. These correlations were mainly located in the salience network and the parietal part of the frontoparietal network. Our findings suggest that resting-state functional connectivity alterations contribute to the age-related decline in TBPM.

Preservation of frontal white matter tracts in ventricular surgery: favoring an anterior interhemispheric transcallosal approach vs a transcortical transfrontal transventricular approach.

Secondary to the creation of a surgical corridor and retraction, white matter tracts degenerate, causing long-term scarring with potential neurological consequences. Third and lateral ventricle tumors require surgery that may lead to cognitive impairment. Our objective is to compare the long-term consequences of a transcortical transfrontal approach and an interhemispheric transcallosal approach on corpus callosum and frontal white matter tracts degeneration. Surgical patients with ventricular tumor accessible through both approaches were included and clinico-radiological data were retrospectively analyzed. The primary endpoint was the callosotomy length at 3-month post-operative T1 MRI, corrected by the extension of the tumor and the use of neuronavigation. Secondary outcomes included perioperative criteria such as bleeding, use of retractors and duration, FLAIR hypersignal on 3-month MRI, and re-do surgeries. To assess white matter tract interruption, 3-month FLAIR hypersignal was superposed to a tractography atlas. Seventy patients were included, 57 (81%) in the transfrontal group and 13 (19%) in the interhemispheric group. There was no difference in the mean callosotomy length on 3-month MRI (12.3mm ± 5.60 transfrontal vs 11.7mm ± 3.92 interhemispheric, p = 0.79) on univariate and multivariate analyses. The callosotomy length was inferior by - 3.13mm for tumors located exclusively in the third ventricle (p = 0.016), independent of the approach. Retractors were used more often in transfrontal approaches (60% vs 33%, p < 0.001). The extent of frontal FLAIR hypersignal was higher after transfrontal approach (14.1mm vs 0.525mm, p < 0.001), correlated to the use of retractors (p < 0.05). After the interhemispheric approach, no tract other than corpus callosum was interrupted, whereas, after the transfrontal approach, frontal arcuate fibers and projections from the thalamus were interrupted in all patients, the cingulum in 19 (33%), the superior fronto-occipital fasciculus in 15 (26%), and the superior longitudinal fasciculus in 2 (3%). Transfrontal and interhemispheric approaches to the third and lateral ventricles both lead to the same long-term damage to the corpus callosum, but the transfrontal approach interrupts several white matter tracts essential to cognitive tasks such as attention and planning, even in the non-dominant hemisphere. These results encourage all neurosurgeons to be familiar with both approaches and favor the interhemispheric approach when both can give access to the tumor with a comparable risk. Neuropsychological studies are necessary to correlate these anatomical findings to cognitive outcomes.

White Matter Microstructure and Gray Matter Volume in Cannabis-Induced Psychosis and Schizophrenia With Cannabis Use.

This study explored the differences in white matter (WM) microstructural integrity and gray matter (GM) volume between cannabis-induced psychosis (CIP) and schizophrenia with cannabis use (SZC). This cross-sectional study with convenience sampling involved three groups of 20 participants each (CIP, SZC, and a control group without substance use), matched on age, handedness, and education. CIP and SZC were diagnosed with the Psychiatric Research Interview for Substance and Mental Disorders. Diffusion tensor and kurtosis imaging were done, and fractional anisotropy (FA), mean diffusivity, and mean kurtosis were estimated. GM volume was measured with voxel-based morphometry. Group comparisons revealed comparable age at initiation and duration and frequency of cannabis use between participants in the SZC and CIP groups. Participants with SZC had lower FA than controls in the anterior and retrolenticular internal capsule limbs, cingulate gyrus hippocampal formation, fornix, and superior fronto-occipital fasciculus (all p<0.05). Participants with CIP had lower FA than controls in the left fornix and right superior fronto-occipital fasciculus but higher FA than those with SZC in the left corticospinal tract (all p<0.05). On morphometry, participants with CIP had greater cerebellar GM volume than those with SZC and greater inferior frontal gyrus volumes than controls (all p<0.05). Widespread WM microstructural abnormalities were observed in participants with SZC, and fewer but significant WM disruptions were observed in those with CIP. Better WM integrity in some WM fiber tracts and greater GM volumes in crucial brain areas among those with CIP may have prevented the transition to schizophrenia.