Global White Matter Research Articles

Effect of xenon on brain injury, neurological outcome, and survival in patients after aneurysmal subarachnoid hemorrhage—study protocol for a randomized clinical trial

BackgroundAneurysmal subarachnoid hemorrhage (aSAH) is a neurological emergency, affecting a younger population than individuals experiencing an ischemic stroke; aSAH is associated with a high risk of mortality and permanent disability. The noble gas xenon has been shown to possess neuroprotective properties as demonstrated in numerous preclinical animal studies. In addition, a recent study demonstrated that xenon could attenuate a white matter injury after out-of-hospital cardiac arrest.MethodsThe study is a prospective, multicenter phase II clinical drug trial. The study design is a single-blind, prospective superiority randomized two-armed parallel follow-up study. The primary objective of the study is to explore the potential neuroprotective effects of inhaled xenon, when administered within 6 h after the onset of symptoms of aSAH. The primary endpoint is the extent of the global white matter injury assessed with magnetic resonance diffusion tensor imaging of the brain.DiscussionDespite improvements in medical technology and advancements in medical science, aSAH mortality and disability rates have remained nearly unchanged for the past 10 years. Therefore, new neuroprotective strategies to attenuate the early and delayed brain injuries after aSAH are needed to reduce morbidity and mortality.Trial registrationClinicalTrials.gov NCT04696523. Registered on 6 January 2021.EudraCT, EudraCT Number: 2019-001542-17. Registered on 8 July 2020.

Associations of MRI-Derived Glymphatic System Impairment With Global White Matter Damage and Cognitive Impairment in Mild Traumatic Brain Injury: A DTI-ALPS Study.

Assessing the glymphatic function using diffusion tensor image analysis along the perivascular space (DTI-ALPS) may be helpful for mild traumatic brain injury (mTBI) management. To assess glymphatic function using DTI-ALPS and its associations with global white matter damage and cognitive impairment in mTBI. Prospective. Thirty-four controls (44.1% female, mean age 49.2 years) and 58 mTBI subjects (43.1% female, mean age 48.7 years), including uncomplicated mTBI (N = 32) and complicated mTBI (N = 26). 3-T, single-shot echo-planar imaging sequence. Magnetic resonance imaging (MRI) was done within 1 month since injury. DTI-ALPS was performed to assess glymphatic function, and peak width of skeletonized mean diffusivity (PSMD) was used to assess global white matter damage. Cognitive tests included Auditory Verbal Learning Test and Digit Span Test (forward and backward). Neuroimaging findings comparisons were done between mTBI and control groups. Partial correlation and multivariable linear regression assessed the associations between DTI-ALPS, PSMD, and cognitive impairment. Mediation effects of PSMD on the relationship between DTI-ALPS and cognitive impairment were explored. P-value <0.05 was considered statistically significant, except for cognitive correlational analyses with a Bonferroni-corrected P-value set at 0.05/3 ≈ 0.017. mTBI showed lower DTI-ALPS and higher PSMD, especially in complicated mTBI. DTI-ALPS was significantly correlated with verbal memory (r = 0.566), attention abilities (r = 0.792), executive function (r = 0.618), and PSMD (r = -0.533). DTI-ALPS was associated with verbal memory (β = 8.77, 95% confidence interval [CI] 5.00, 12.54), attention abilities (β = 5.67, 95% CI 4.56, 6.97), executive function (β = 2.34, 95% CI 1.49, 3.20), and PSMD (β = -0.79, 95% CI -1.15, -0.43). PSMD mediated 46.29%, 20.46%, and 24.36% of the effects for the relationship between DTI-ALPS and verbal memory, attention abilities, and executive function. Glymphatic function may be impaired in mTBI reflected by DTI-ALPS. Glymphatic dysfunction may cause cognitive impairment related to global white matter damage after mTBI. 2 TECHNICAL EFFICACY: Stage 2.

Higher allostatic load is associated with poorer structural integrity in the limbic network in cognitively unimpaired elderly

AbstractBackgroundAllostatic load (AL) is a cumulative measure of dysregulations across multiple physiological systems of the body occurring over time. AL was originally developed to explain how chronic stress damages physiologic systems and accelerates aging. Studies exploring the relationship between AL and brain health in older adults using a multimodal approach are limited. Our objective was to provide a comprehensive overview of the brain substrates of AL in cognitively unimpaired elderly using complementary multimodal neuroimaging techniques.MethodBaseline data of 111 cognitively unimpaired older adults (mean age, 68.9years) from the Age‐Well study (NCT02977819) were included. They underwent multimodal neuroimaging (T1‐weighted and diffusion MRI, FDG‐PET and amyloid‐PET). A global measure of brain integrity was obtained for each modality by extracting the averaged signal across the whole gray matter (GM) or white matter (WM) for diffusion. AL was computed based on 19 markers of health. First, we examined the relationships between AL and sex or age. Second, we performed multiple regression and voxel‐wise analyses to predict AL from each neuroimaging modality and to highlight the brain regions involved. Finally, we conducted forward stepwise multiple regressions including the 19 AL‐components to determine the prognostic components of each of these associations; correcting for age, sex and education.ResultAL was associated with sex (men&gt;women) but not with age. Higher AL was associated with lower global GM volume and WM mean diffusivity. Adjusting for alcohol consumption, smoking habits, treatments or comorbidities, these associations remained unchanged. Association with lower GM volume was found in the parahippocampus, hypothalamus, anterior insula and prefrontal gyrus and with WM diffusivity in the corona radiata and corpus callosum. Stepwise regressions revealed that these associations with GM volume and WM diffusivity were mainly explained by the body mass index (BMI) and waist‐hip‐ratio (WHR), respectively.ConclusionHigher AL is associated with poorer structural integrity in regions of the limbic network, which is implicated in memory, emotion and stress processes and known to be particularly vulnerable to Alzheimer’s disease. Our results further suggest that maintenance of a healthy weight (by monitoring BMI and WHR) might help to prevent AL increase, thus promoting brain health.

Dietary pattern and brain structure among young adults

AbstractBackgroundEnvironmental factors, such as nutrition, influence brain physiology and health throughout the life course. While research has focused on the extremes of the age spectrum, less is known about early adulthood, yet a critical period for the consolidation of brain maturation and the building of adult behaviors. Nutrition may impact late maturational changes in the post‐adolescent brain and contribute to the degree of brain reserve that minimizes the risk to develop dementia. We took advantage of a large sample of young adults to evaluate the association of dietary behavior with brain structure characteristics.MethodThis cross‐sectional study included 1721 university students (18‐35 years‐old) from the French i‐Share cohort, who underwent brain MRI. A 12‐item online Food Frequency Questionnaire was used to evaluate consumption in major food groups and to determine dietary patterns from Principal Component Analysis (PCA). Multivariable‐adjusted linear regressions were used to estimate the association of PCA scores with brain structure (cortical thickness and surface area, grey matter and white matter volumes, diffusion parameters).ResultThe first PCA component (explained variance, 17%) contrasted a healthy diet (higher fruit and vegetable intakes) to a poor diet (higher fast food, sugary drink and snack consumptions). In models adjusted for total intracranial volume, age, sex, physical activity, body mass index, alcohol and tobacco consumptions, a higher PCA score (reflecting healthier diet) was associated with lower total gray matter volume (β for 1 point score = –0.17 [95%CI, –0.31; –0.03] cm3), in various brain areas (Figure). Healthy diet was also associated with lower global white matter volume (β = –0.18 [–0.32; –0.03] cm3). No association was found with diffusion tensor imaging, and neurite orientation dispersion and density imaging metrics in the white matter.ConclusionIn this large sample of young adults, healthier diet was associated with lower brain volumes, independent of multiple potential confounders. Gray matter volume loss during post‐adolescence is a marker of brain maturation; thus, environmental factors emphasizing this loss may benefit maturation. Our results raise the hypothesis that a healthy diet may favor and a poor diet may hamper brain maturation; an assumption which deserves further investigation in other populations.

Complement C3a treatment accelerates recovery after stroke via modulation of astrocyte reactivity and cortical connectivity.

Despite advances in acute care, ischemic stroke remains a major cause of long-term disability. Approaches targeting both neuronal and glial responses are needed to enhance recovery and improve long-term outcome. The complement C3a receptor (C3aR) is a regulator of inflammation with roles in neurodevelopment, neural plasticity, and neurodegeneration. Using mice lacking C3aR (C3aR-/-) and mice overexpressing C3a in the brain, we uncovered two opposing effects of C3aR signaling on functional recovery after ischemic stroke: inhibition in the acute phase and facilitation in the later phase. Peri-infarct astrocyte reactivity was increased and density of microglia reduced in C3aR-/- mice, C3a overexpression led to the opposite effects. Pharmacological treatment of wild-type mice with intranasal C3a starting 7 days after stroke accelerated recovery of motor function and attenuated astrocyte reactivity without enhancing microgliosis. C3a treatment stimulated global white matter reorganization, increased peri-infarct structural connectivity and upregulated Igf1 and Thbs4 in the peri-infarct cortex. Thus, C3a treatment from day 7 after stroke exerts positive effects on astrocytes and neuronal connectivity while avoiding the deleterious consequences of C3aR signaling during the acute phase. Intranasal administration of C3aR agonists within convenient time window holds translational promise to improve outcome after ischemic stroke.

Axon fiber orientation as the source of T1 relaxation anisotropy in white matter: A study on corpus callosum in vivo and ex vivo.

Recent studies indicate that T1 in white matter (WM) is influenced by fiber orientation in B0 . The purpose of the study was to investigate the interrelationships between axon fiber orientation in corpus callosum (CC) and T1 relaxation time in humans in vivo as well as in rat brain ex vivo. Volunteers were scanned for relaxometric and diffusion MRI at 3 T and 7 T. Angular T1 plots from WM were computed using fractional anisotropy and fiber-to-field-angle maps. T1 and fiber-to-field angle were measured in five sections of CC to estimate the effects of inherently varying fiber orientations on T1 within the same tracts in vivo. Ex vivo rat-brain preparation encompassing posterior CC was rotated in B0 and T1 , and diffusion MRI images acquired at 9.4 T. T1 angular plots were determined at several rotation angles in B0 . Angular T1 plots from global WM provided reference for estimated fiber orientation-linked T1 changes within CC. In anterior midbody of CC in vivo, where small axons are dominantly present, a shift in axon orientation is accompanied by a change in T1 , matching that estimated from WM T1 data. In CC, where large and giant axons are numerous, the measured T1 change is about 2-fold greater than the estimated one. Ex vivo rotation of the same midsagittal CC region of interest produced angular T1 plots at 9.4 T, matching those observed at 7 T in vivo. These data causally link axon fiber orientation in B0 to the T1 relaxation anisotropy in WM.

Aberrant topology of white matter networks in patients with methamphetamine dependence and its application in support vector machine-based classification

Brain white matter (WM) networks have been widely studied in neuropsychiatric disorders. However, few studies have evaluated alterations in WM network topological organization in patients with methamphetamine (MA) dependence. Therefore, using machine learning classification methods to analyze WM network topological attributes may give new insights into patients with MA dependence. In the study, diffusion tensor imaging-based probabilistic tractography was used to map the weighted WM networks in 46 MA-dependent patients and 46 control subjects. Using graph-theoretical analyses, the global and regional topological attributes of WM networks for both groups were calculated and compared to determine inter-group differences using a permutation-based general linear model. In addition, the study used a support vector machine (SVM) learning approach to construct a classifier for discriminating subjects with MA dependence from control subjects. Relative to the control group, the MA-dependent group exhibited abnormal topological organization, as evidenced by decreased small-worldness and modularity, and increased nodal efficiency in the right medial superior temporal gyrus, right pallidum, and right ventromedial putamen; the MA-dependent group had the higher hubness scores in 25 regions, which were mainly located in the default mode network. An SVM trained with topological attributes achieved classification accuracy, sensitivity, specificity, and kappa values of 98.09% ± 2.59%, 98.24% ± 4.00%, 97.94% ± 4.26%, and 96.18% ± 5.19% for patients with MA dependence. Our results may suggest altered global WM structural networks in MA-dependent patients. Furthermore, the abnormal WM network topological attributes may provide promising features for the construction of high-efficacy classification models.

Cerebral blood flow in children with persisting postconcussive symptoms and posttraumatic headache at 2 weeks postconcussion.

Persisting postconcussive symptoms (pPCS), particularly headache, can significantly disrupt children's recovery and functioning. However, the underlying pathophysiology of these symptoms remains unclear. The goal in this study was to determine whether pPCS are related to cerebral blood flow (CBF) at 2 weeks postconcussion. The authors also investigated whether variations in CBF can explain the increased risk of acute posttraumatic headache (PTH) in female children following concussion. As part of a prospective, longitudinal study, the authors recruited children 5-18 years old who were admitted to the emergency department of a tertiary pediatric hospital with a concussion sustained within 48 hours of admission. Participants underwent pseudocontinuous arterial spin labeling MRI at 2 weeks postconcussion to quantify global mean gray and white matter perfusion (in ml/100 g/min). Conventional frequentist analysis and Bayesian analysis were performed. Comparison of recovered (n = 26) and symptomatic (n = 12) groups (mean age 13.15 years, SD 2.69 years; 28 male) found no differences in mean global gray and white matter perfusion at 2 weeks postconcussion (Bayes factors > 3). Although female sex was identified as a risk factor for PTH with migraine features (p = 0.003), there was no difference in CBF between female children with and without PTH. Global CBF was not associated with pPCS and female PTH at 2 weeks after pediatric concussion. These findings provide evidence against the use of CBF measured by arterial spin labeling as an acute biomarker for pediatric concussion recovery.

Disrupted structural connectivity and less efficient network system in patients with the treatment-naive adult attention-deficit/hyperactivity disorder.

Attention-deficit/hyperactivity disorder (ADHD) is a neuropsychiatric disorder whose primary symptoms are hyperactivity, impulsivity, and inattention. Historically, ADHD was recognized as a disease of childhood and adolescence. However, many patients are known to have persistent symptoms into adulthood. Many researchers consider the neuropathology of ADHD to be based on abnormalities in multiple parallel and intersecting pathways rather than a single anatomical area, but such alterations remain to be clarified. Using diffusion tensor imaging, we investigated differences in the global network metrics estimated by graph theory and the degree of connectivity between adjacent voxels within a white matter (WM) fascicle defined by the density of the diffusing spins (connectometry) between 19 drug-naive Japanese patients with adult ADHD and 19 matched healthy controls (HCs). In adult patients with ADHD, we examined the relationships between the symptomatology of ADHD and global network metrics and WM abnormalities. Compared with HCs, adult patients with ADHD showed a reduced rich-club coefficient and decreased connectivity in widely distributed WMs such as the corpus callosum, the forceps, and the cingulum bundle. Correlational analyses demonstrated that the general severity of ADHD symptoms was associated with several global network metrics, such as lower global efficiency, clustering coefficient, small worldness, and longer characteristic path length. The connectometry revealed that the severity of hyperactive/impulsive symptoms was associated with overconnectivity in the corticostriatal, corticospinal, and corticopontine tracts, the inferior fronto-occipital fasciculus, and the extreme capsule but dysconnectivity in the cerebellum. The severity of inattentive symptoms was associated with dysconnectivity in the intracerebellar circuit and some other fibers. The results of the present study indicated that patients with treatment-naive adult ADHD showed disrupted structural connectivity, which contributes to less efficient information transfer in the ADHD brain and pathophysiology of ADHD. UMIN Clinical Trials Registry (UMIN-CTR) UMIN000025183, Registered: 5 January 2017.

Abstract 109: Regional Cerebral Hypoperfusion In Patients Recovered From Mild COVID-19

Background: Cerebral hypoperfusion have been described in both severe and mild forms of symptomatic coronavirus disease 2019 (COVID-19) infection. The purpose of this study was to investigate global and regional gray matter (GM) and white matter (WM) cerebral blood flow (CBF) in asymptomatic COVID-19 infection patients compared with age-gender-race matched controls. Methods: Cases with mild COVID-19 infection and age-gender-race matched healthy controls, were drawn from the ABC@UofSC data repository. Demographics, risk factors and data from the Montreal Cognitive Assessment (MOCA score) were collected within a week of magnetic resonance imaging (MRI) perfusion image acquisition using pseudo-continuous arterial spin labeling. Mean CBF values for GM, WM and whole brain were calculated by averaging CBF values of standard space normalized CBF image values falling within GM and WM masks. Whole-brain, region of interest (ROI) based analyses were used to create standardized cerebral blood flow maps and further explore differences between the two groups. Results: Twenty-eight cases with prior mild COVID-19 infection were compared with 28 age-, gender-, race-matched controls. The MOCA score was similar between cases and controls. Whole-brain CBF (46.7±5.6 vs. 49.3±3.7, p=0.05), GM-specific CBF (64.2±8.9 vs. 67.6±6.0, p=0.10), and WM-specific CBF (29.3±2.6 vs. 31.0±1.6, p=0.03) were noted to be lower in COVID-19 cases as compared to controls. Further analysis identified several brain regions with lower CBF than the CONTROL group colors representing Z-scores shown in the figure. Predictive models based on these data predicted COVID-19 group membership with a high degree of accuracy (85.2%) suggesting CBF patterns as a key imaging marker of mild infection. Conclusion: In this study, lower white matter CBF, as well as widespread regional CBF changes identified using quantitative MRI, were found in patients recovered from mild to moderate COVID-19 infection.

Altered cerebral blood flow and white matter during wakeful rest in patients with obstructive sleep apnea: a population-based retrospective study.

To explore changes in cerebral blood flow (CBF) and white matter during wakeful rest in patients with obstructive sleep apnea (OSA). The subjects comprised OSA patients and age- and sex-matched non-sleep apnea (NSA) subjects from December 2020 to December 2021. All subjects underwent structural and arterial spin labeling MRI examinations using a 3.0 T MRI scanner. Intergroup differences in regional and global CBF and white matter hyperintensities (WMHs) were analyzed. In this study, 100 (74 males) of 750 (439 males) subjects were diagnosed with OSA, so the prevalence of OSA in the general population was 13.3% (100/750), with 16.9% (74/439) in males and 8.4% (26/311) in females. Excluding four patients with incomplete imaging data, 96 OSA patients and 103 age- and sex-matched NSA subjects were included. At global level, OSA patients showed significantly decreased CBF values in gray matter and whole brain compared to NSA subjects (gray matter: p = 0.010; whole brain: p = 0.021). No significant difference in CBF values was found in WM between the two groups (p = 0.250). At regional level, compared with NSA subjects, patients with OSA exhibited significantly decreased regional CBF values mainly in right parietal lobe and right temporal lobe. Moreover, OSA patients had significantly higher WMHs burden than NSA subjects (p = 0.017). OSA patients exhibit decreased global and regional CBF values and increased WMHs burden. These findings provide a basis for exploring neuropathological changes of OSA and for early and appropriate treatment.

Brain development after intrauterine exposure to lithium: A magnetic resonance imaging study in school-age children.

Lithium is often continued during pregnancy to reduce the risk of perinatal mood episodes for women with bipolar disorder. However, little is known about the effect of intrauterine lithium exposure on brain development. The aim of this study was to investigate brain structure in children after intrauterine exposure to lithium. Participants were offspring, aged 8-14 years, of women with a diagnosis of bipolar spectrum disorder. In total, 63 children participated in the study: 30 with and 33 without intrauterine exposure to lithium. Global brain volume outcomes and white matter integrity were assessed using structural MRI and diffusion tensor imaging, respectively. Primary outcomes were total brain, cortical and subcortical gray matter, cortical white matter, lateral ventricles, cerebellum, hippocampus and amygdala volumes, cortical thickness, cortical surface area and global fractional anisotropy, and mean diffusivity. To assess how our data compared to the general population, global brain volumes were compared to data from the Generation R study (N=3243). In our primary analyses, we found no statistically significant associations between intrauterine exposure to lithium and structural brain measures. There was a non-significant trend toward reduced subcortical gray matter volume. Compared to the general population, lithium-exposed children showed reduced subcortical gray and cortical white matter volumes. We found no differences in brain structure between lithium-exposed and non-lithium-exposed children aged 8-14 years following correction for multiple testing. While a rare population to study, future and likely multi-site studies with larger datasets are required to validate and extend these initial findings.

Polygenic risk scores and brain structures both contribute to externalizing behavior in childhood - A study in the Adolescent Brain and Cognitive Development (ABCD) cohort

IntroductionExternalizing behaviors are defined as behaviors violating social norms and can be harmful to self and others. Predicting the escalation of externalizing behaviors in children would allow for early interventions to prevent the occurrence of antisocial and criminal acts. Externalizing behaviors are heritable traits, and have been associated with structures of the brain. Brain structure, in turn, is also influenced by genetics. Here, we investigated the association of genetic and brain structural variation with externalizing behaviors in late childhood, and we assessed potential mediating effects. MethodsData was collected for 11,878 children aged 9–10 years old from the Adolescent Brain Cognitive Development (ABCD) cohort. We extracted data on externalizing behaviors measured by the parent-reported Child Behavior Checklist (CBCL), brain volumes and white matter integrity measured by magnetic resonance imaging (MRI), and polygenic risk scores (PRS) for (i) antisocial behaviors, (ii) attention-deficit/hyperactivity disorder comorbid with disruptive behavior disorder (ADHD ​+ ​DBD), (iii) irritability, and (iv) traits related to self-regulation & addiction. We examined the associations between brain structures, PRS, and externalizing behavior, and to what extent brain structures mediate the association between PRS and externalizing behavior. Phenotypic associations between brain structures and externalizing behaviors were validated in an independent cohort of 150 adolescents aged 12–21 years enriched for individuals with antisocial behavior. ResultsIncreasing levels of externalizing behaviors were associated with reduced total brain and focal gray matter volumes, but not with white matter integrity. These results could not be validated in the independent cohort, except for a good correlation of several effect sizes between the cohorts. Higher PRS for externalizing behaviors were associated with lower cortical gray matter volume, larger subcortical gray matter volume, larger white matter volume, and reduced global white matter fractional anisotropy. Genetic and brain structural variation, combined with sociodemographic factors, explained up to 7% of variation in externalizing behaviors in late childhood; brain structures and PRS each explained up to ∼0.5% of variation. A multivariate model with all sociodemographic factors, brain structures and PRS combined explained up to 11.9% (+5%). Total cortical gray matter volume mediated the association between PRS for ADHD ​+ ​DBD and externalizing behavior in late childhood. However, a large proportion of individual variation in externalizing behavior remained unidentified (∼90%). Brain function and interaction effects with the environment are surmised as potential sources of additional variation.

Periventricular and juxtacortical characterization of UManitoba-JHU functionally defined human white matter atlas networks.

The open-access UManitoba-JHU functionally defined human white matter (WM) atlas contains specific WM pathways and general WM regions underlying 12 functional brain networks in ICBM152 template space. However, it is not known whether any of these WM networks are disproportionately co-localized with periventricular and/or juxtacortical WM (PVWM and JCWM), which could potentially impact their ability to infer network-specific effects in future studies-particularly in patient populations expected to have disproportionate PVWM and/or JCWM damage. The current study therefore identified intersecting regions of PVWM and JCWM (defined as WM within 5 mm of the ventricular and cortical boundaries) and: (1) the ICBM152 global WM mask, and (2) all 12 UManitoba-JHU WM networks. Dice Similarity Coefficient (DSC), Jaccard Similarity Coefficient (JSC), and proportion of volume (POV) values between PVWM (and JCWM) and each functionally defined WM network were then compared to corresponding values between PVWM (and JCWM) and global WM. Between the 12 WM networks and PVWM, 8 had lower DSC, JSC, and POV; 1 had lower DSC and JSC, but higher POV; and 3 had higher DSC, JSC, and POV compared to global WM. For JCWM, all 12 WM networks had lower DSC, JSC, and POV compared to global WM. The majority of UManitoba-JHU functionally defined WM networks exhibited lower than average spatial similarity with PVWM, and all exhibited lower than average spatial similarity with JCWM. This suggests that they can be used to explore network-specific WM changes, even in patient populations with known predispositions toward PVWM and/or JCWM damage.

Lower fractional anisotropy without evidence for neuro-inflammation in patients with early-phase schizophrenia spectrum disorders

Various lines of research suggest immune dysregulation as a potential therapeutic target for negative and cognitive symptoms in schizophrenia spectrum disorders (SSD). Immune dysregulation would lead to higher extracellular free-water (EFW) in cerebral white matter (WM), which may partially underlie the frequently reported lower fractional anisotropy (FA) in SSD. We aim to investigate differences in EFW concentrations – a presumed proxy for neuro-inflammation – between early-phase SSD patients (n = 55) and healthy controls (HC; n = 37), and to explore immunological and cognitive correlates. To increase specificity for EFW, we study several complementary magnetic resonance imaging contrasts that are sensitive to EFW. FA, mean diffusivity (MD), magnetization transfer ratio (MTR), myelin water fraction (MWF) and quantitative T1 and T2 were calculated from diffusion-weighted imaging (DWI), magnetization transfer imaging (MTI) and multicomponent driven equilibrium single-pulse observation of T1/T2 (mcDESPOT). For each measure, WM skeletons were constructed with tract-based spatial statistics. Multivariate SSD-HC comparisons with WM skeletons and their average values (i.e. global WM) were not statistically significant. In voxel-wise analyses, FA was significantly lower in SSD in the genu of the corpus callosum and in the left superior longitudinal fasciculus (p < 0.04). Global WM measures did not correlate with immunological markers (i.e. IL1-RA, IL-6, IL-8, IL-10 and CRP) or cognition in HC and SSD after corrections for multiple comparisons. We confirmed lower FA in early-phase SSD patients. However, nonFA measures did not provide additional evidence for immune dysregulation or for higher EFW as the primary mechanism underlying the reported lower FA values in SSD.

EFFECT OF A 6-MONTH HOME-BASED WALKING PROGRAM ON COGNITIVE FITNESS IN OLDER ADULTS WITH CHRONIC KIDNEY DISEASE

Abstract We have previously demonstrated that cognitive status and white matter integrity are highly associated with physical fitness in older adult patients with chronic kidney disease (CKD). We present data from a two group RCT determining effect of a 6-month home-based walking intervention on physical and cognitive fitness compared to usual care. The intervention included use of a wearable activity monitor, weekly didactic phone meetings, interactive tools and monthly coach-delivered feedback. The intervention group had a 78% compliance rate to the 6-month exercise program (159.9 (149.2) minutes/week). Executive function composite score and global cognitive for intervention group &amp;gt; than control group. Additionally, global white matter integrity and functional connectivity improved in the intervention group and declined in the usual care group. We conclude that a home-based physical activity intervention can have significant improvement on cognitive health and neuroplasticity in older adults with CKD and lowering their risk of developing AD/ADRD

Mapping white matter structural and network alterations in betel quid-dependent chewers using high angular resolution diffusion imaging.

To evaluate brain white matter diffusion characteristics and anatomical network alterations in betel quid dependence (BQD) chewers using high angular resolution diffusion imaging (HARDI). The current study recruited 53 BQD chewers and 37 healthy controls (HC) in two groups. We explored regional diffusion metrics alternations in the BQD group compared with the HC group using automated fiber quantification (AFQ). We further employed the white matter (WM) anatomical network of HARDI to explore connectivity alterations in BQD chewers using graph theory. BQD chewers presented significantly lower FA values in the left and right cingulum cingulate, the left and right thalamic radiation, and the right uncinate. The BQD has a significantly higher RD value in the right uncinate fasciculus than the HC group. At the global WM anatomical network level, global network efficiency (p = 0.008) was poorer and Lp (p = 0.016) was greater in the BQD group. At the nodal WM anatomical network level, nodal efficiency (p < 0.05) was lower in the BQD group. Our findings provide novel morphometric evidence that brain structural changes in BQD are characterized by white matter diffusivity and anatomical network connectivity among regions of the brain, potentially leading to the enhanced reward system and impaired inhibitory control.

In vivo biomarkers of arteriolosclerosis are associated with ADRD biomarkers

AbstractBackgroundBrain arteriolosclerosis, which involves thickening of the vessel wall and stenosis of arterioles, is one of the main pathologies of cerebral small vessel disease, and often co‐occurs with other pathology indicative of Alzheimer’s disease and related disorders (ADRD). A novel classifier of arteriolosclerosis, ARTS, was recently developed by the MarkVCID consortium for in vivo studies of arteriolosclerosis. We hypothesized that higher levels of arteriolosclerosis are associated with worse ADRD biomarker levels.Method109 participants from the Wake Forest Alzheimer’s Disease Research Center’s Clinical Core underwent clinical and cognitive evaluation, 3T brain MRI, and PiB (amyloid) PET (n=92). Participants were adjudicated by NIA‐AA criteria as having normal cognition (n=69), mild cognitive impairment (n=25), or dementia (n=15). Raw T1, FLAIR, and TOPUP and Eddy Current Corrected DTI images along with age and sex were inputs to a machine learning based classifier generating ARTS scores; higher ARTS indicates higher likelihood of arteriolosclerosis. For variables of interest, T1 MRI were processed (FreeSurfer v5.3) to calculate cortical gray matter (GM), hippocampal, and intracranial (ICV) volumes, and temporal meta‐ROI cortical thickness. White matter hyperintensity (WMH) volumes were calculated on FLAIR with LST in SPM12. NODDI were processed using AMICO to generate mean Free Water (FW) in hippocampus and global GM and white matter (WM). A set of AD‐sensitive cortical ROIs were used to extract mean PET SUVr signal. Separate multivariable general linear models (GLM) examined relationships between ARTS and variables of interest adjusted initially for age and total ICV (Table 1), and then again after adjusting for additional covariates (sex, race, education, APOE‐e4 carrier status, and clinical diagnosis).ResultAmong 109 participants (71±7 years, 60% women), ARTS ranged from ‐.80 to .29 (mean±SD = ‐.37±.20), suggesting a low overall likelihood of arteriolosclerosis in our sample. Higher ARTS was significantly associated with lower cortical thickness, higher WMH, higher WM FW, and greater amyloid deposition (Table 1). When adjusting for additional covariates, only amyloid no longer significantly associated with ARTS (p=0.19).ConclusionHigher ARTS scores are cross‐sectionally associated with other abnormalities in ADRD biomarkers. Future directions will examine the relationship between ARTS and Flortaucipir (tau) uptake.

In vivo biomarkers of arteriolosclerosis are associated with ADRD biomarkers

AbstractBackgroundBrain arteriolosclerosis, which involves thickening of the vessel wall and stenosis of arterioles, is one of the main pathologies of cerebral small vessel disease, and often co‐occurs with other pathology indicative of Alzheimer’s disease and related disorders (ADRD). A novel classifier of arteriolosclerosis, ARTS, was recently developed by the MarkVCID consortium for in vivo studies of arteriolosclerosis. We hypothesized that higher levels of arteriolosclerosis are associated with worse ADRD biomarker levels.Method109 participants from the Wake Forest Alzheimer’s Disease Research Center’s Clinical Core underwent clinical and cognitive evaluation, 3T brain MRI, and PiB (amyloid) PET (n=92). Participants were adjudicated by NIA‐AA criteria as having normal cognition (n=69), mild cognitive impairment (n=25), or dementia (n=15). Raw T1, FLAIR, and TOPUP and Eddy Current Corrected DTI images along with age and sex were inputs to a machine learning based classifier generating ARTS scores; higher ARTS indicates higher likelihood of arteriolosclerosis. For variables of interest, T1 MRI were processed (FreeSurfer v5.3) to calculate cortical gray matter (GM), hippocampal, and intracranial (ICV) volumes, and temporal meta‐ROI cortical thickness. White matter hyperintensity (WMH) volumes were calculated on FLAIR with LST in SPM12. NODDI were processed using AMICO to generate mean Free Water (FW) in hippocampus and global GM and white matter (WM). A set of AD‐sensitive cortical ROIs were used to extract mean PET SUVr signal. Separate multivariable general linear models (GLM) examined relationships between ARTS and variables of interest adjusted initially for age and total ICV (Table 1), and then again after adjusting for additional covariates (sex, race, education, APOE‐e4 carrier status, and clinical diagnosis).ResultAmong 109 participants (71±7 years, 60% women), ARTS ranged from ‐.80 to .29 (mean±SD = ‐.37±.20), suggesting a low overall likelihood of arteriolosclerosis in our sample. Higher ARTS was significantly associated with lower cortical thickness, higher WMH, higher WM FW, and greater amyloid deposition (Table 1). When adjusting for additional covariates, only amyloid no longer significantly associated with ARTS (p=0.19).ConclusionHigher ARTS scores are cross‐sectionally associated with other abnormalities in ADRD biomarkers. Future directions will examine the relationship between ARTS and Flortaucipir (tau) uptake.

Higher allostatic load is associated with poorer structural integrity in the limbic network in cognitively unimpaired elderly

AbstractBackgroundAllostatic load (AL) is a cumulative measure of dysregulations across multiple physiological systems of the body occurring over time. AL was originally developed to explain how chronic stress damages physiologic systems and accelerates aging. Studies exploring the relationship between AL and brain health in older adults using a multimodal approach are limited. Our objective was to provide a comprehensive overview of the brain substrates of AL in cognitively unimpaired elderly using complementary multimodal neuroimaging techniques.MethodBaseline data of 111 cognitively unimpaired older adults (mean age, 68.9years) from the Age‐Well study (NCT02977819) were included. They underwent multimodal neuroimaging (T1‐weighted and diffusion MRI, FDG‐PET and amyloid‐PET). A global measure of brain integrity was obtained for each modality by extracting the averaged signal across the whole gray matter (GM) or white matter (WM) for diffusion. AL was computed based on 19 markers of health. First, we examined the relationships between AL and sex or age. Second, we performed multiple regression and voxel‐wise analyses to predict AL from each neuroimaging modality and to highlight the brain regions involved. Finally, we conducted forward stepwise multiple regressions including the 19 AL‐components to determine the prognostic components of each of these associations; correcting for age, sex and education.ResultAL was associated with sex (men&gt;women) but not with age. Higher AL was associated with lower global GM volume and WM mean diffusivity. Adjusting for alcohol consumption, smoking habits, treatments or comorbidities, these associations remained unchanged. Association with lower GM volume was found in the parahippocampus, hypothalamus, anterior insula and prefrontal gyrus and with WM diffusivity in the corona radiata and corpus callosum. Stepwise regressions revealed that these associations with GM volume and WM diffusivity were mainly explained by the body mass index (BMI) and waist‐hip‐ratio (WHR), respectively.ConclusionHigher AL is associated with poorer structural integrity in regions of the limbic network, which is implicated in memory, emotion and stress processes and known to be particularly vulnerable to Alzheimer’s disease. Our results further suggest that maintenance of a healthy weight (by monitoring BMI and WHR) might help to prevent AL increase, thus promoting brain health.