Left Forceps Research Articles

Causal Relationship between Aging and Anorexia Nervosa: A White-Matter-Microstructure-Mediated Mendelian Randomization Analysis.

This study employed a two-step Mendelian randomization analysis to explore the causal relationship between telomere length, as a marker of aging, and anorexia nervosa and to evaluate the mediating role of changes in the white matter microstructure across different brain regions. We selected genetic variants associated with 675 diffusion magnetic resonance imaging phenotypes representing changes in brain white matter. F-statistics confirmed the validity of the instruments, ensuring robust causal inference. Sensitivity analyses, including heterogeneity tests, horizontal pleiotropy tests, and leave-one-out tests, validated the results. The results show that telomere length is significantly negatively correlated with anorexia nervosa in a unidirectional manner (p = 0.017). Additionally, changes in specific white matter structures, such as the internal capsule, corona radiata, posterior thalamic radiation, left cingulate gyrus, left longitudinal fasciculus, and left forceps minor (p < 0.05), were identified as mediators. These findings enhance our understanding of the neural mechanisms, underlying the exacerbation of anorexia nervosa with aging; emphasize the role of brain functional networks in disease progression; and provide potential biological targets for future therapeutic interventions.

The effect of live music therapy on white matter microstructure in very preterm infants – A randomized controlled trial

ObjectiveMusic therapy (MT) is proposed to enrich the acoustic environment of very preterm infants (VPT) on the neonatal intensive care unit during a vulnerable period of brain development. The objective of this study was to investigate the effect of MT on the white matter (WM) microstructure. It is hypothesized that MT affects WM integrity in VPT. MethodsRandomized controlled trial enrolling infants born <32 weeks’ gestation. Infants were randomized to MT or standard care. Live MT was provided twice weekly from the second postnatal week onwards by a trained music therapist. At term equivalent age, participants underwent a cranial magnetic resonance imaging scan including sequences for diffusion tensor imaging analysis. Differences in WM microstructure were assessed using tract based spatial statistics with fractional anisotropy. ResultsOf 80 infants enrolled, 42 were eligible for diffusion tensor imaging analysis (MT: n = 22, standard care: n = 20). While primary tract based spatial statistics analysis revealed no significant differences between groups, post hoc analysis with uncorrected p-values and a significance threshold of p < 0.01 revealed significant fractional anisotropy differences in several WM tracts including the bilateral superior longitudinal fasciculus, the left forceps minor and left fasciculus uncinatus, the corpus callosum, the left external capsule, and the right corticospinal tract. ConclusionPost hoc analysis results suggest an effect of MT on WM integrity in VPT. Larger studies including long-term outcome are necessary to confirm these effects of MT on WM microstructure and to assess its impact on clinical neurodevelopment. Clinical trial registrationClinical trial number DRKS00025753.

Plasma oligomer βeta‐amyloid and white matter microstructural integrity in cognitively normal older adults according to cerebral amyloid deposition

AbstractBackgroundMultimer detection system‐oligomeric amyloid‐ß (MDS‐OAß) measures plasma OAß level, which is associated with earlier pathology of Alzheimer’s disease (AD). Previous studies showed that plasma levels of MDS‐OAβ were higher in patients with dementia due to AD than in cognitive normal older adults (CN), and they correlated well with conventional AD biomarkers including standardized uptake value ratio (SUVR) of Pittsburgh compound B (PiB) and CSF level of Aβ42, p‐Tau, and t‐Tau. However, no previous study investigated MDS‐OAβ difference in CN with or without cerebral Aβ burden. In addition, associations among MDS‐OAß, cerebral Aß deposition, aberrance of white matter integrity, and cortical thickness in CN is not elucidated.MethodWe studied 34 CN with amyloid‐PET negative and 23 CN with amyloid‐PET positive results who received MDS‐OAβ, structural MRI, and diffusion tensor imaging (DTI).ResultAmyloid‐PET positive group showed higher MDS‐OAß level than amyloid‐PET negative group, but two groups did not differ in WM integrity or cortical thickness. MDS‐OAβ level was significantly higher in amyloid‐PET positive group than in amyloid‐PET negative group. MDS‐OAβ positive group had significantly higher cerebral AB deposition, or mean global SUVR values, than MDS‐OAβ negative group. There was a positive correlation between MDS‐OAβ level and PET‐SUVR. In terms of DTI analysis, MDS‐OAβ positive group had significantly lower FA in the left forceps minor of corpus callosum and right superior longitudinal fasciculus than in lower MDS‐OAβ negative group. In addition, the FA values were negatively correlated with MDS‐OAβ level (figure 1). MDS‐OAB positive group showed a significant reduction in the cortical thickness in the left fusiform when compared with the MDS‐OAB negative groupConclusionPlasma MDS‐OAβ value might reflect cerebral amyloid status and global cerebral Aß retention in CN. We elucidated toxic role of OAβ by showing that the plasma OAβ value were associated with decrement of WM microstructural integrity in the early pathological process of AD. Cortical thickness did not differ according to cerebral Aβ burden but rather was associated with higher plasma OAβ level. Thus, MDS‐OAβ value might reflect earlier, and different, pathology than cerebral Aß retention measured using amyloid PET scan in CN with AD continuum.

White Matter Changes as an Independent Predictor of Alzheimer's Disease.

Abnormalities in white matter (WM) may be a crucial physiologic feature of Alzheimer's disease (AD). However, neuroimaging's ability to visualize the underlying functional degradation of the WM region in AD is unclear. This study aimed to explore the differences in amplitude of low-frequency fluctuation (ALFF) and fractional ALFF (fALFF) in the WM region of patients with AD and healthy controls (HC) and to investigate further whether these values can provide supplementary information for diagnosing AD. Forty-eight patients with AD and 46 age-matched HC were enrolled and underwent resting-state functional magnetic resonance imaging and a neuropsychological battery assessment. We analyzed the differences in WM activity between the two groups and further explored the correlation between WM activity in the different regions and cognitive function in the AD group. Finally, a machine learning algorithm was adopted to construct a classifier in detecting the clinical classification ability of the values of ALFF/ALFF in the WM. Compared with HCs, patients with AD had lower WM activity in the right anterior thalamic radiation, left frontal aslant tract, and left forceps minor, which are all positively related to global cognitive function, memory, and attention function (all p < 0.05). Based on the combined WM ALFF and fALFF characteristics in the different regions, individuals not previously assessed were classified with moderate accuracy (75%), sensitivity (71%), specificity (79%), and area under the receiver operating characteristic curve (85%). Our results suggest that WM activity is reduced in AD and can be used for disease classification.

Plasma Oligomer β-Amyloid and White Matter Microstructural Integrity in Cognitively Normal Older Adults According to Cerebral Amyloid Deposition.

Multimer detection system-oligomeric amyloid-β (MDS-OAβ) measure plasma OAβ level, which is associated with earlier Alzheimer's disease (AD) pathology. However, no study has investigated MDS-OAβ differences in cognitive normal older adults (CN) with or without cerebral Aβ burden and its correlation with Aβ deposition and white matter (WM) integrity. To investigate associations among cerebral Aβ burden, MDS-OAβ, and WM integrity in CN. This is a single center, cross-sectional study which used data from Catholic Aging Brain Imaging (CABI) database. CABI database contains brain scans of patients who visited the outpatient clinic at Catholic Brain Health Center, Yeouido St. Mary's Hospital, The Catholic University of Korea, between 2017 and 2022. A total 34 amyloid-PET negative CN and 23 amyloid-PET positive CN were included. Plasma Aβ level using MDS-OAβ, cerebral Aβ deposition level using global standardized uptake value ratio (SUVR) values, WM integrity using fractional anisotropy (FA) and mean diffusivity (MD), and cortical thickness from structural MRI were utilized. The amyloid-PET positive group showed higher MDS-OAβ level than the amyloid-PET negative group (0.997 ± 0.19 vs. 0.79 ± 0.28, P <0.005), but they did not differ in WM integrity or cortical thickness. The MDS-OAβ positive group showed higher global cerebral Aβ deposition or mean global SUVR values (0.609 ± 0.135 vs. 0.533 ± 0.121 vs. P <0.05), lower regional FA of left forceps minor and the right superior longitudinal fasciculus (family-wise error rate, p <0.05), and lower cortical thickness of left fusiform (p <0.05, Monte Carlo simulation) than the MDS-OAβ negative group. MDS-OAβ was positively associated with global cerebral Aβ deposition (r=0.278, P <0.05) and negatively associated (r = - 0.324, P < 0.05) with regional WM integrity. In this study, MDS-OAβ value demonstrated earlier and different AD pathology than cerebral Aβ retention according to amyloid-PET. Longitudinal studies are needed to elucidate the causal relationships of plasma OAβ and cerebral Aβ with WM integrity disturbance and cortical atrophy during the AD trajectory.

White matter changes following electroconvulsive therapy for depression: a multicenter ComBat harmonization approach

ECT is proposed to exert a therapeutic effect on WM microstructure, but the limited power of previous studies made it difficult to highlight consistent patterns of change in diffusion metrics. We initiated a multicenter analysis and sought to address whether changes in WM microstructure occur following ECT. Diffusion tensor imaging (DTI) data (n = 58) from 4 different sites were harmonized before pooling them by using ComBat, a batch-effect correction tool that removes inter-site technical variability, preserves inter-site biological variability, and maximizes statistical power. Downstream statistical analyses aimed to quantify changes in Fractional Anisotropy (FA), Mean Diffusivity (MD), Radial Diffusivity (RD) and Axial Diffusivity (AD), by employing whole-brain, tract-based spatial statistics (TBSS). ECT increased FA in the right splenium of the corpus callosum and the left cortico-spinal tract. AD in the left superior longitudinal fasciculus and the right inferior fronto-occipital fasciculus was raised. Increases in MD and RD could be observed in overlapping white matter structures of both hemispheres. At baseline, responders showed significantly smaller FA values in the left forceps major and smaller AD values in the right uncinate fasciculus compared with non-responders. By harmonizing multicenter data, we demonstrate that ECT modulates altered WM microstructure in important brain circuits that are implicated in the pathophysiology of depression. Furthermore, responders appear to present a more decreased WM integrity at baseline which could point toward a specific subtype of patients, characterized by a more altered neuroplasticity, who are especially sensitive to the potent neuroplastic effects of ECT.

An analysis of the correlation between the efficacy of training using a high-fidelity disease-specific simulator and the clinical outcomes of laparoscopic surgery for congenital biliary dilatation in pediatric patients.

The present study clarified the efficacy of repeating laparoscopic surgery training using a disease-specific simulator and investigated the clinical outcomes of laparoscopic surgery for congenital biliary dilatation (CBD) in pediatric patients after training. A high-fidelity laparoscopic hepaticojejunostomy simulator was used. Four pediatric surgeons performed practice laparoscopic hepaticojejunostomy three times using the simulator. The details of forceps manipulation during the task were analyzed. The clinical outcomes of 13 CBD cases treated with laparoscopic surgery in our institution were also evaluated based on medical records. The time required to complete the task became significantly shorter each successive time (1st: 1062.18 ± 346.79s vs. 3rd: 717.44 ± 260.80s, p = 0.039). There were no significant differences in the total path length of the right forceps (1st: 55.56 ± 23.21m vs. 3rd: 28.25 ± 17.01m, p = 0.17), total path length of the left forceps (1st: 47.79 ± 20.79m vs. 3rd: 31.83 ± 17.62m, p = 0.17), average velocity of the right forceps (1st: 58.78 ± 21.29mm/s vs.44.98 ± 10.25mm/s, p = 0.47), or the average velocity of the left forceps (1st: 50.39 ± 19.25mm/s vs. 52.26 ± 19.59mm/s, p = 0.78). Regarding the clinical outcome, all CBD patients underwent laparoscopic surgery performed by practiced pediatric surgeons who had no experience. The operative time was 545.53 ± 91.01min, and the blood loss was 24.2 ± 25.8ml. There were no cases of open conversion, intraoperative adverse events, or anastomotic leakage. Disease-specific simulator training significantly decreased the task performance time by improving the forceps manipulation economy. In addition, simulator training may improve the operative safety and quality of laparoscopic hepaticojejunostomy in pediatric CBD patients.

White matter pathways associated with empathy in females: A DTI investigation

Empathy is a component of social cognition that allows us to understand, perceive, experience, and respond to the emotional state of others. In this study, we seek to build on previous research that suggests that sex and hormone levels may impact white matter microstructure. These white matter microstructural differences may influence social cognition. We examine the fractional anisotropy (FA) of white matter pathways associated with the complex human process of empathy in healthy young adult females during the self-reported luteal phase of their menstrual cycle. We used tract-based spatial statistics to perform statistical comparisons of FA and conducted multiple linear regression analysis to examine the strength of association between white matter FA and scores on the Empathy Quotient (EQ), a self-report questionnaire in which individuals report how much they agree or disagree with 60 statements pertaining to their empathic tendencies. Results identified a significant negative relationship between EQ scores and FA within five clusters of white matter: in the left forceps minor/body of the corpus callosum, left corticospinal tract, intraparietal sulcus/primary somatosensory cortex, superior longitudinal fasciculus, and right inferior fronto-occipital fasciculus/forceps minor. These consistent findings across clusters suggest that lower self-reported empathy is related to higher FA across healthy young females in specific white matter regions during the menstrual luteal phase. Future research should seek to examine if self-reported empathy varies across the menstrual cycle, using blood samples to confirm cycle phase and hormone levels.

Cerebrospinal Fluid sTREM2 Has Paradoxical Association with Brain Structural Damage Rate in Early- and Late-Stage Alzheimer's Disease.

Recently it has been proposed that microglial response has a stage-dependent effect on the progression of Alzheimer's disease (AD). Cerebrospinal fluid (CSF) sTREM2 has emerged as a promising microglial activation marker. To test the stage-dependent role of microglia by studying the association between baseline sTREM2 and dynamic brain structural changes in AD and mild cognitive impairment (MCI) patients. 22 amyloid-β-positive (A+) and tau-positive (T+) AD and 24 A+T+MCI patients were identified from the Alzheimer's Disease Neuroimaging Initiative. The patients had baseline CSF amyloid-β, phosphorylated-tau, and sTREM2, and were followed up for at least one year by T1-weighted and diffusion tensor imaging scans. Gray matter volumes and white matter microstructural integrity were evaluated. Linear mixed models were applied to analyze how baseline sTREM2 may influence the rate of brain structural changes while adjusting for the effects of age, APOE4 status, and the CSF core markers. In A+T+AD patients, baseline CSF sTREM2 was associated with faster mean diffusivity increase in the bilateral posterior corona radiata and right superior longitudinal fasciculus. In A+T+MCI patients, baseline CSF sTREM2 was associated slower gray matter volumetric loss in parahippocampal gyrus, left fusiform cortex, left middle temporal gyrus, and left lateral occipital cortex. Baseline CSF sTREM2 also had a protective effect against mean diffusivity increase in right inferior fronto-occipital fasciculus, left superior longitudinal fasciculus, left forceps minor, and left uncinate fasciculus. Microglial activation at early stage might have a protective effect against neurodegeneration, while at late stage it might facilitate AD. Future efforts on modulating microglial activation could be promising, given a carefully selected time window for intervention.

White matter changes following electroconvulsive therapy for depression: a mega-analysis

IntroductionElectroconvulsive therapy (ECT) is proposed to exert an effect on white matter (WM) microstructure, but the limited power of previous studies made it difficult to highlight consistent patterns of change in diffusion metrics.ObjectivesWe initiated a multi-site mega-analysis and sought to address whether changes in WM microstructure occur following ECT.Methods To this end, diffusion tensor imaging (DTI) data (n=58) from 4 different sites were harmonized before pooling them by using ComBat, a batch-effect correction tool that removes inter-site technical variability, preserves inter-site biological variability and maximizes statistical power. Downstream statistical analyses aimed to quantify changes in Fractional anisotropy (FA), Mean Diffusivity (MD), Radial Diffusivity (RD) and Axial Diffusivity (AD), by employing whole-brain, tract-based spatial statistics (TBSS).ResultsECT increases FA in the right splenium of the corpus callosum and the left cortico-spinal tract. Both the left superior longitudinal fasciculus and the right inferior fronto-occipital fasciculus showed increases in AD. Increases in MD and RD could be observed in overlapping white matter structures of both hemispheres. Finally, responders showed significantly smaller FA values in the left forceps major and smaller AD values in the right uncinate fasciculus compared with non-responders.ConclusionsThis is the first and largest multi-site mega-analysis to demonstrate that ECT normalizes altered WM microstructure in important brain circuits that are implicated in the pathophysiology of depression. Furthermore, responders appear to present a more decreased WM integrity at baseline, which if replicated could serve as a biomarker for ECT response.DisclosureNo significant relationships.

White matter diffusion abnormalities observed in cognitively normal elderly before conversion to mild cognitive impairment

AbstractBackgroundDifferences in white matter (WM) microstructure, as measured with diffusion tensor imaging (DTI), have been observed between cognitively normal, mild cognitively impaired (MCI), and Alzheimer’s disease (AD) patient groups. With increased focus on early intervention for AD, detection of preclinical changes is paramount; however, due to difficulties in predicting future conversion, few studies have investigated WM deterioration prior to symptom onset. Using DTI data from the Vallecas project (an 8‐year longitudinal study of healthy elderly individuals), we determine if WM changes can be found in cognitively normal individuals before conversion to MCI.MethodsFrom a baseline cohort of 824 cognitively normal 70‐85 year olds, 65 individuals converted to MCI over the study duration (mean age 77.0±4.29 years, 58% female). 65 non‐converters were matched by age, sex, and years of education to act as controls. DTI scans from one year before conversion were analysed using tract‐based spatial statistics implemented in FSL. Fractional anisotropy (FA), mean diffusivity (MD), and mode of anisotropy (MO) were compared between groups using non‐parametric permutation tests. A second comparison between future converters and all 759 non‐converters (mean age 74.0±3.92 years, 65% female) was also conducted, using age, sex, and years of education as covariates.ResultsIn the unmatched comparisons, controls had higher FA in the left forceps minor (ForMin) and anterior corona radiata (CR) (p&lt;0.05), and higher MO along the corpus callosum (CC) and ForMin (p&lt;0.01). Future converters had higher FA in the left posterior CR and corticospinal tract (p&lt;0.05), higher MD in the left anterior CR (p&lt;0.05), and higher MO along the bilateral projection fibres (p&lt;0.01). In the matched comparison, only MO differences were observed, with higher MO in controls along the body of the CC (p&lt;0.05), and higher MO in future converters in the left projection fibres and the splenium of the CC (p&lt;0.01). All significant results were FWE‐corrected.ConclusionsOur results suggest that frontal commissural fibres begin to deteriorate in cognitively normal subjects destined to convert to MCI, whilst also demonstrating selective preservation of projection fibres. We also find that MO is a sensitive measure of white matter microstructural changes presaging cognitive decline, even in preclinical populations.

White matter microstructure and connectivity in patients with obsessive‐compulsive disorder and their unaffected siblings

We aimed to examine white matter microstructure and connectivity in individuals with obsessive-compulsive disorder (OCD) and their unaffected siblings, relative to healthy controls. Diffusion-weighted magnetic resonance imaging (dMRI) scans were acquired in 30 patients with OCD, 21 unaffected siblings, and 31 controls. We examined white matter microstructure using measures of fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD). Structural networks were examined using network-based statistic (NBS). Compared to controls, OCD patients showed significantly reduced FA and increased RD in clusters traversing the left forceps minor, inferior fronto-occipital fasciculus, anterior thalamic radiation, and cingulum. Furthermore, the OCD group displayed significantly weaker connectivity (quantified by the streamline count) compared to controls in the right hemisphere, most notably in edges connecting subcortical structures to temporo-occipital cortical regions. The sibling group showed intermediate streamline counts, FA and RD values between OCD and healthy control groups in connections found to be abnormal in patients with OCD. However, these reductions did not significantly differ compared to controls. Therefore, siblings of OCD patients display intermediate levels in dMRI measures of microstructure and connectivity, suggesting white matter abnormalities might be related to the familial predisposition for OCD.

The correlation between white matter integrity and pragmatic language processing in first episode schizophrenia

Objective: Higher-order language disturbances could be the result of white matter tract abnormalities. The study explores the relationship between white matter and pragmatic skills in first-episode schizophrenia. Methods: Thirty-four first-episode patients with schizophrenia and 32 healthy subjects participated in a pragmatic language and Diffusion Tensor Imaging study, where fractional anisotropy of the arcuate fasciculus, corpus callosum and cingulum was correlated with the Polish version of the Right Hemisphere Language Battery. Results: The patients showed reduced fractional anisotropy in the right arcuate fasciculus, left anterior cingulum bundle and left forceps minor. Among the first episode patients, reduced understanding of written metaphors correlated with reduced fractional anisotropy of left forceps minor, and greater explanation of written and picture metaphors correlated with reduced fractional anisotropy of the left anterior cingulum. Conclusions: The white matter dysfunctions may underlie the pragmatic language impairment in schizophrenia. Our results shed further light on the functional neuroanatomical basis of pragmatic language use by patients with schizophrenia.

Cerebral microstructural abnormalities in impulsivity: a magnetic resonance study.

Studies that investigated neurobiological parameters subtended to impulsivity trait found their relationship with structural and functional brain alterations. No studies investigated the white matter microstructural attributes of impulsivity in a large sample of healthy subjects. In the present study 1007 subjects from Human Connectome Project public dataset were divided in two groups, impulsive and not impulsive, basing on Delay Discounting task score. For both groups brain morphometric and microstructural characteristics were investigated. A t-test (correct for multiple comparisons) was performed for each brain parcel and impulsivity measure. Magnetic resonance diffusion images were pre-processed and selected to perform a voxelwise analysis on the fractional anisotropy (FA) maps between impulsive and not impulsive groups. Group analysis showed significant differences in morphometric brain data mainly for temporal and frontal lobes. The impulsive group presented higher FA values in four regions: bilateral medial lemniscus and midbrain reticular formation, right superior longitudinal fasciculus, left forceps major, right corticospinal tract. Not impulsive group showed higher FA values in two significant regions: right and left anterior thalamus radiation. Concluding, macroscopic and microstructural brain alterations were assessed, identifying new neuroanatomical substrates for multidimensional impulsivity construct in a large sample of healthy subjects.

Impact and Characteristics of Forceps Manipulation of Three-Dimensional in Laparoscopic Hepaticojejunostomy Mimicking a Disease-Specific Simulator: A Comparison of Expert with Trainee.

Purpose: Various studies have shown the benefit of three-dimensional (3D) systems over two-dimensional (2D) systems in endoscopic surgery. However, few studies have focused on pediatric endosurgery. The purpose of this study was to assess the impact of 2D and 3D environments on the time taken and forceps manipulation by comparing experts and trainees using a laparoscopic hepaticojejunostomy simulator. Methods: We have developed a simulator of laparoscopic hepaticojejunostomy for congenital biliary dilatation. Seventeen participants of pediatric surgeons (4 experts and 13 trainees) performed hepaticojejunostomy using our simulator in both 2D and 3D environment. We evaluated the required time, total path length, and average velocities of bilateral forceps in both situations. Results: Obtained results show the findings for the required time (seconds; 2D, experts: 810.43 ± 321.64 vs. trainees: 1136.02 ± 409.96, P = .17) (seconds; 3D, experts: 660.21 ± 256.48 vs. trainees: 1017 ± 280.93, P = .039), total path length of right forceps (mm; 2D, experts: 38838.23 ± 30686.63 vs. trainees: 52005.47 ± 31675.02, P = .48)(mm; 3D, experts: 24443.09 ± 12316.32 vs. trainees: 45508.09 ± 26926.27, P = .16), total path length of left forceps (mm; 2D, experts: 131635.54 ± 71669.94 vs. trainees: 245242.48 ± 130940.25, P = .48)(mm; 3D, experts: 88520.42 ± 56766.63 vs. trainees: 230789.75 ± 107315.85, P = .024), average velocities of right forceps (mm/second; 2D, experts: 44.80 ± 21.85 vs. trainees: 44.37 ± 18.92, P = .97) (mm/second; 3D, experts: 37.28 ± 16.49 vs. trainees: 42.58 ± 14.40, P = .54), average velocities of left forceps (mm/second; 2D, experts: 156.65 ± 38.69 vs. trainees: 202.58 ± 63.80, P = .20) (mm/second; 3D, experts: 125.64 ± 44.30 vs. trainees: 219.42 ± 43.82, P < .01). Conclusion: The experts performed more effectively when using the 3D system. Using 3D, the total path length of the left forceps of expert pediatric surgeons was significantly shorter than trainee pediatric surgeons, and the average velocities of the left forceps tip of expert pediatric surgeons was significantly slower than trainee pediatric surgeons. These results suggest that training of assisting hand is necessary for advanced pediatric endosurgery to avoid organ injury.

Effect of aerobic exercise on white matter microstructure in the aging brain

Aging is associated with decline in white matter (WM) microstructure, decreased cognitive functioning, and increased risk of Alzheimer’s disease and related dementias. Recent research has identified aerobic physical exercise as a promising intervention for increasing white matter microstructure in aging, with the aim of increasing cognitive abilities, and protecting against neurodegenerative processes. However, the degree to which white matter microstructure can be protected or improved with exercise remains incompletely understood. Here, a sub-group of 25 healthy, sedentary participants (aged 57 to 86 years; M = 67.1; SD = 7.9; 11 female, 14 male) from the larger Brain in Motion Study (Tyndall et al., 2013) underwent diffusion tensor imaging (DTI) before and after a six-month aerobic exercise intervention. DTI data were analysed with FSL’s Tract-Based Spatial Statistics (TBSS) to determine whether WM microstructure improved, as defined by increased fractional anisotropy (FA) and/or decreased mean diffusivity (MD), after the aerobic exercise intervention. Neither FA nor MD of the cerebral WM were significantly correlated with either age or cardiovascular fitness at baseline. Whole-brain WM mean FA decreased over the intervention while mean MD showed no significant change. Longitudinal TBSS analyses revealed decreased FA in the left uncinate fasciculus, left anterior corona radiata, left inferior fronto-occipital fasciculus, and left anterior thalamic radiation. MD increased in the left forceps major, left inferior longitudinal fasciculus, and left superior longitudinal fasciculus. Results indicate that six months of aerobic exercise in healthy, sedentary older adults was not associated with improvements in FA or MD measures of cerebral WM microstructure.

Visual Attention Performances and Related Cerebral Microstructural Integrity Among Subjects With Subjective Cognitive Decline and Mild Cognitive Impairment.

Objective: To compare visual attention performances and diffusion tensor imaging (DTI) between subjects with subjective cognitive decline (SCD) and mild cognitive impairment (MCI), and to discover neuronal substrates related to visual attention performances.Methods: Thirty-nine subjects with SCD and 15 with MCI, diagnosed following neuropsychological tests and conventional brain magnetic resonance imaging, were recruited. All subjects were further examined by the Conners Continuous Performance Test 3 (CPT3) and DTI including fractional anisotropy (FA) and mean diffusivity (MD), in which group comparisons and stepwise linear regression were made.Results: Subjects with MCI had a worse performance in all retrieval indices of verbal/nonverbal memory tests than those with SCD in the context of comparable general cognition and demographic status. In the CPT3, subjects with MCI had a significant longer hit reaction time (HRT) by univariate but not multivariate comparisons. Further analysis suggested that a longer HRT across all interstimuli intervals and at the point of fourth to sixth blocks were noted among MCI subjects. In DTI evaluations, FA value within the left forceps major was the only hotspot with significant between-group differences after the Bonferroni correction of FA and MD values. On the basis that HRT had significant inverse correlations with FA value within the genu of the corpus callosum and left forceps minor, regression analysis was conducted, showing HRT was best predicted by the FA value within the left forceps minor. Area under receiver operative characteristic curve was 0.70; the optimum cut-off for HRT was 515.8 ms, with a sensitivity of 85% but specificity of 47%.Conclusions: Our report suggested that impaired sustained attention and vigilance to be an early cognitive marker in differentiating MCI from SCD, where MCI subjects had a longer HRT across all interstimuli intervals and more profoundly in later blocks. FA measures appeared to be more sensitive DTI parameters than MD values in detecting microstructural changes between SCD and MCI. The role of the anterior interhemispheric fibers in sustained attention implementation during visual signal detection task was highlighted.

Association of excessive social media use with abnormal white matter integrity of the corpus callosum

Borrowing from findings regarding other problematic behaviors, we posit that excessive social media use (ESMU) can relate to impaired inter-hemispheric connections. These are often reflected in impaired white matter integrity (decreased fractional anisotropy and increased mean diffusivity) of the corpus callosum. We test this idea with diffusion tensor imaging (DTI) data from 20 normal social media users with varying degrees of ESMU. The findings of a Regions of Interest analysis focusing on the corpus callosum indicate that ESMU is associated with increased mean diffusivity in the body and splenium sub-regions of the corpus callosum. Whole-brain Tract Based Spatial Statistics analysis revealed that ESMU is positively associated with mean diffusivity of left superior and inferior longitudinal fasciculi as well as left forceps minor; and that ESMU is positively associated with the fractional anisotropy of the right Corticospinal Tract. It is concluded that inter-hemispheric white matter deficits in the corpus callosum extended to forceps minor, as well as along the ventral semantic path can be associated with ESMU.

White Matter Integrity Disruptions Correlate With Cognitive Impairments in Asthma.

Cognitive impairments are common in asthma, which is a serious global health problem characterized by chronic airway inflammation. However, the underlying neuromechanism is still unclear. To investigate the neuromechanism underlying cognitive impairments of asthma. We hypothesized that asthma patients exhibit altered white matter (WM) microstructures, which may contribute to their cognitive impairments. Case-control study. 37 patients with asthma (14 male) and 31 healthy controls (10 male). Diffusion tensor imaging (DTI) covering the whole brain was acquired on a 3.0T scanner using a single-shot echo planar imaging sequence. A DTI with tract-based spatial statistics (TBSS) approach was used to investigate the whole-brain differences in the WM fractional anisotropy (FA) values. Demographic and neuropsychological data were performed using two independent sample t-test or chi-square test or Mann-Whitney rank test. The relationship between cognitive impairments and WM abnormalities was studied using correlation analyses. Impairments of language ability, executive function, and visual-spatial processing and widespread WM disruptions reflected by FA reduction were found in asthma patients. The executive function was related to left forceps major, cingulum, and right uncinate fasciculus, ILF (inferior longitudinal fasciculus) positively (P < 0.05). FA abnormalities were positively correlated with duration of asthma and asthma control test (ACT) scores. Asthma patients display multiple cognitive impairments and universally WM integrity disruptions, among which executive dysfunction closely correlates with WM abnormalities. 1 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018.

Effectiveness of diffusion tensor imaging in differentiating early-stage subcortical ischemic vascular disease, Alzheimer's disease and normal ageing.

ObjectiveTo describe and compare diffusion tensor imaging (DTI) parameters between patients with subcortical ischemic vascular disease (SIVD) and Alzheimer’s disease (AD) diagnosed using structuralized neuropsychiatric assessments, and investigate potential neuronal substrates related to cognitive performance.MethodsThirty-five patients with SIVD, 40 patients with AD, and 33 cognitively normal control (NC) subjects matched by age and education level were consecutively recruited and underwent cognitive function assessments and DTI examinations. Comparisons among these three subgroups with regards to cognitive performance and DTI parameters including fractional anisotropy (FA) and mean diffusivity (MD) values were performed. Partial correlation analysis after controlling for age and education was used to evaluate associations between cognitive performance and DTI parameters.ResultsWith regards to cognitive performance, the patients with SIVD had lower total scores in frontal assessment battery (FAB) compared to those with AD (p < 0.05) in the context of comparable Mini-Mental Status Examination and Cognitive Abilities Screening Instrument scores. With regards to DTI parameters, there were more regions of significant differences in FA among these three subgroups compared with MD. Compared with NC group, the patients with SIVD had significant global reductions in FA (p < 0.001 ~ 0.05), while significant reductions in FA among the patients with AD were regionally confined within the left superior longitudinal fasciculus, genu and splenium of the corpus callosum, and bilateral forceps major, and the anterior thalamic radiation, uncinate fasciculus, and cingulum of the left side (p < 0.01 ~ 0.05). Analysis of FA values within the left forceps major, left anterior thalamic radiation, and genu of the corpus callosum revealed a 71.8% overall correct classification (p < 0.001) with sensitivity of 69.4%, specificity of 73.8%, positive predictive value of 69.4%, and negative predictive value of 73.8% in discriminating patients with SIVD from those with AD. In combined analysis of the patients with SIVD and AD (n = 75), the total FAB score was positively correlated with FA within the bilateral forceps minor, genu of the corpus callosum, left forceps major, left uncinate fasciculus, and right inferior longitudinal fasciculus (p = 0.001 ~ 0.038), and inversely correlated with MD within the right superior longitudinal fasciculus, genu and body of the corpus callosum, bilateral forceps minor, right uncinate fasciculus, and right inferior longitudinal fasciculus (p = 0.003 ~ 0.040)ConclusionsOur findings suggest the effectiveness of DTI measurements in distinguishing patients with early-stage AD from those with SIVD, with discernible changes in spatial distribution and magnitude of significance of the DTI parameters. Strategic FA assessments provided the most robust discriminative power to differentiate SIVD from AD, and FAB may serve as an additional cognitive marker. We also identified the neuronal substrates responsible for FAB performance.