Network structure-function coupling and neurocognition in cerebral small vessel disease

Background: Cerebral small vessel disease is a leading cause of cognitive decline and vascular dementia. Small vessel disease pathology changes structural brain networks, but its impact on functional networks remains poorly understood. Structural and functional networks are closely coupled in healthy individuals, and decoupling is associated with clinical symptoms in other neurological conditions. We tested the hypothesis that structural–functional network coupling is related to neurocognitive outcomes in 262 small vessel disease patients. Methods: Participants underwent multimodal magnetic resonance imaging and cognitive assessment in 2011 and 2015. Structural connectivity networks were reconstructed using probabilistic diffusion tractography, while functional connectivity networks were estimated from resting-state functional magnetic resonance imaging. Structural and functional networks were then correlated to calculate a measure of structural–functional network coupling for each participant. Results: Lower whole-brain coupling was associated with reduced processing speed and greater apathy both cross-sectionally and longitudinally. In addition, coupling within the cognitive control network was associated with all cognitive outcomes, suggesting that neurocognitive outcomes in small vessel disease may be related to the functioning of this intrinsic connectivity network. Conclusions: Our work demonstrates the influence of structural–functional connectivity network decoupling in small vessel disease symptomatology. Cognitive control network function may be investigated in future studies

Baseline Cerebral Small Vessel Disease Is Not Associated with Gait Decline After Five Years

Background Cerebral small vessel disease (SVD) is cross-sectionally associated with gait disturbances, however, the relation between baseline SVD and gait decline over time is uncertain. Furthermore, diffusion tensor imaging (DTI) studies on gait decline are currently lacking. Objective To investigate the association between baseline imaging SVD markers and gait decline. Methods In 2006, 310 participants from the RUN DMC cohort, a prospective cohort with older adults aged 50–85 years with SVD, were included. Gait variables were assessed using a computerized walkway during baseline and follow-up. Linear and logistic regression analyses were used to investigate the relation between imaging measures and gait decline and incident gait impairment (speed ≤ 1.0 m/s). Tract-based spatial statistics (TBSS) was used to identify possible differences in DTI measures of white matter tracts between participants with and without incident gait impairment. Results Mean age was 63.3 years (SD: 8.4) and mean follow-up duration 5.4 years (SD: 0.2). No significant associations between imaging measures and gait decline were found. TBSS analysis revealed no significant differences in DTI measures between participants with and without incident gait impairment after additional adjustment for SVD. In sub-analyses, a high total WMH volume (OR: 2.8 for highest quartile, 95% CI: 1.1–7.1) and high infratentorial WMH volume (OR: 1.8 per SD increase, 95% CI: 1.1–2.9) were associated with an increased 5-year risk of gait impairment, although this was not significant after correction for multiple testing. Conclusion Baseline imaging SVD markers were not associated with gait decline or incident gait impairment after 5 years. Future studies should investigate if SVD progression is related to gait deterioration

Simple MRI score aids prediction of dementia in cerebral small vessel disease

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