Dataset Information

Cortical Microinfarcts and White Matter Connectivity in Memory Clinic Patients.

ABSTRACT: Background and purpose: Cerebral microinfarcts (CMIs) are associated with cognitive impairment and dementia. CMIs might affect cognitive performance through disruption of cerebral networks. We investigated in memory clinic patients whether cortical CMIs are clustered in specific brain regions and if presence of cortical CMIs is associated with reduced white matter (WM) connectivity in tracts projecting to these regions. Methods:164 memory clinic patients with vascular brain injury with a mean age of 72 ± 11 years (54% male) were included. All underwent 3 tesla MRI, including a diffusion MRI and cognitive testing. Cortical CMIs were rated according to established criteria and their spatial location was marked. Diffusion imaging-based tractography was used to reconstruct WM connections and voxel based analysis (VBA) to assess integrity of WM directly below the cortex. WM connectivity and integrity were compared between patients with and without cortical CMIs for the whole brain and regions with a high CMI burden. Results:30 patients (18%) had at least 1 cortical CMI [range 1-46]. More than 70% of the cortical CMIs were located in the superior frontal, middle frontal, and pre- and postcentral brain regions (covering 16% of the cortical surface). In these high CMI burden regions, presence of cortical CMIs was not associated with WM connectivity after correction for conventional neuroimaging markers of vascular injury. WM connectivity in the whole brain and WM voxels directly underneath the cortical surface did not differ between patients with and without cortical CMIs. Conclusion:Cortical CMIs displayed a strong local clustering in highly interconnected frontal, pre- and postcentral brain regions. Nevertheless, WM connections projecting to these regions were not disproportionally impaired in patients with compared to patients without cortical CMIs. Alternative mechanisms, such as focal disturbances in cortical structure and functioning, may better explain CMI associated cognitive impairment.

SUBMITTER: Ferro D

PROVIDER: S-EPMC6560058 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Cortical Microinfarcts and White Matter Connectivity in Memory Clinic Patients.

Ferro Doeschka D Heinen Rutger R de Brito Robalo Bruno B Kuijf Hugo H Biessels Geert Jan GJ Reijmer Yael Y

Frontiers in neurology 20190605

<b>Background and purpose:</b> Cerebral microinfarcts (CMIs) are associated with cognitive impairment and dementia. CMIs might affect cognitive performance through disruption of cerebral networks. We investigated in memory clinic patients whether cortical CMIs are clustered in specific brain regions and if presence of cortical CMIs is associated with reduced white matter (WM) connectivity in tracts projecting to these regions. <b>Methods:</b>164 memory clinic patients with vascular brain injury ...[more]

PMID: 31231301

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Project description:Background/objectivesMemory clinic patients commonly also have declined physical performance. This may be attributable to white matter injury, due to vascular damage or neurodegeneration. Quantifying white matter injury is made possible by new magnetic resonance imaging (MRI) techniques, including diffusion-weighted imaging (DWI) of network connectivity. We investigated whether physical performance in memory clinic patients is related to white matter network connectivity.DesignObservational cross-sectional study.SettingMemory clinic.ParticipantsPatients referred to a memory clinic with vascular brain injury on MRI (n = 90; average age = 72 years; 60% male; 34% with diagnosis Alzheimer disease).MeasurementsWe reconstructed structural brain networks from DWI with fiber tractography and used graph theory to calculate global efficiency, fractional anisotropy (FA), and mean diffusivity (MD) of the white matter, and nodal strength (mean FA or MD of all white matter tracts connected to a node). Assessment of physical performance included gait speed, chair stand time, and Short Physical Performance Battery (SPPB) score.ResultsLower global efficiency, lower FA, and higher MD correlated with poorer gait speed, SPPB scores, and chair stand times (R range = 0.23-0.42). Global efficiency and FA explained 5% to 16% of the variance in gait speed, chair stand times, and SPPB scores, independent of age and sex. Moreover, global efficiency and FA explained an additional 4% to 5% of variance on top of lacunar infarcts and white matter hyperintensities. Regional analyses showed that, in particular, the connectivity strength of prefrontal, occipital, striatal, and thalamic nodes correlated with gait speed.ConclusionPoorer physical performance is related to disrupted white matter network connectivity in memory clinic patients with vascular brain injury. The associations of these network abnormalities are partially independent of visible vascular injury. J Am Geriatr Soc 67:1880-1887, 2019.

Project description:Numerous studies have used functional magnetic resonance imaging (fMRI) to characterize functional connectivity between cortical regions by analyzing correlations in blood oxygenation level dependent (BOLD) signals in a resting state. However, to date, there have been only a handful of studies reporting resting state BOLD signals in white matter. Nonetheless, a growing number of reports has emerged in recent years suggesting white matter BOLD signals can be reliably detected, though their biophysical origins remain unclear. Moreover, recent studies have identified robust correlations in a resting state between signals from cortex and specific white matter tracts. In order to further validate and interpret these findings, we studied a non-human primate model to investigate resting-state connectivity patterns between parcellated cortical volumes and specific white matter bundles. Our results show that resting-state connectivity patterns between white and gray matter structures are not randomly distributed but share notable similarities with diffusion- and histology-derived anatomic connectivities. This suggests that resting-state BOLD correlations between white matter fiber tracts and the gray matter regions to which they connect are directly related to the anatomic arrangement and density of WM fibers. We also measured how different levels of baseline neural activity, induced by varying levels of anesthesia, modulate these patterns. As anesthesia levels were raised, we observed weakened correlation coefficients between specific white matter tracts and gray matter regions while key features of the connectivity pattern remained similar. Overall, results from this study provide further evidence that neural activity is detectable by BOLD fMRI in both gray and white matter throughout the resting brain. The combined use of gray and white matter functional connectivity could also offer refined full-scale functional parcellation of the entire brain to characterize its functional architecture.

Dataset Information

Cortical Microinfarcts and White Matter Connectivity in Memory Clinic Patients.

Publications

Cortical Microinfarcts and White Matter Connectivity in Memory Clinic Patients.

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