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Abstract Mobility impairment is a geriatric giant. Particularly, slow gait is associated with elevated risk for cognitive decline, disabilities and dementia. Gait is the product of complex neural network interactions and changes in their connectivity pattern may negatively impact gait speed. However, mechanistic neural correlates for gait speed maintenance and decline remained unclear. As such, the aim of this study is to investigate differences in neural network connectivity in older adults with and without gait speed decline over 24 months. This sub-analysis included 35 community-dwelling older adults age >70 years from the MOBILIZE Boston Study. Baseline assessments included four-meter gait speed test and resting-state fMRI. Gait speed was reassessed at a 24-month follow-up. Participants were stratified to “Maintainer” and “Decliner” groups based upon a cut-off of >0.05 m/s decline in gait speed from baseline to follow-up. A priori selected functional network included sensori-motor network (SMN) and frontoparietal network (FPN). Multivariate analysis of variance was performed to determine between group differences in network connectivity. Discriminant analysis was conducted to identify relative contribution of network connectivity to group classification. Between the 14 Maintainers and 21 Decliners (mean age 83.9 years), Maintainers were younger (p=0.088). After adjusting for age, Maintainers exhibited lower SMN premotor-precentral gyrus connectivity (p=0.023), greater FPN ventral visual-supramarginal gyrus connectivity (p=0.025), and trend level greater SMN-FPN cerebellum-occipital connectivity (p=0.053). Premotor-precentral gyrus connectivity showed greatest contribution to discriminant function. These preliminary findings suggest aberrant connectivity patterns of the SMN and FPN may be predictive of older adults’ ability to maintain gait speed.

Background: Hip joint congruency and stability in fractures are affected by posterior wall fragment size and percentage compared with the normal side. Computed tomography (CT) scan is a useful tool to precisely evaluate the morphologic features of acetabular fractures. Aim: The aim of this study was to establish an accurate and reliable method of measuring acetabular posterior wall fracture fragment percentages on three-dimensional (3D) CT scan reconstruction images. Methods: CT scans of eight patients with acetabular posterior wall fractures were reviewed by five orthopedic surgeons. Posterior wall fracture fragment percentages were measured using three methods: (1) linear measurement percentages on axial CT images, (2) linear measurement percentages on 3D reconstruction images, and (3) acetabular posterior surface area measurements using computer software (gold standard). Analysis of variance testing was used to compare these methods. Dunn's multiple comparison test was used to compare the accuracy of the axial CT scan and 3D reconstruction methods to the gold standard method. Results: There were no significant differences between two of the eight patients (25%) in fracture fragment percentage measurements using all methods. Dunn's multiple comparison test showed that the axial CT scan method measurement was significantly different from the gold standard measurement in four of the eight patients (50%), three of whom sustained more than an 80% fracture. However, there was no significant difference between the 3D reconstruction and gold standard methods in all study patients. Inter- and intra-observer reliabilities were excellent for all three methods. Conclusion: The 3D reconstruction image method is reliable and accurate for measuring acetabular posterior wall fracture fragment percentages. [ABSTRACT FROM AUTHOR]

Background Slow gait is predictive of functional impairments in older adults, while concomitant slow gait and cognitive complaints are associated with a greater risk for cognitive decline and dementia. However, functional neural correlates for gait speed maintenance are unclear. As the sensorimotor network (SMN) and frontoparietal network (FPN) are integral components of these functions, this study investigated differences in SMN and FPN in older adults with/without gait speed decline over 24 months; and whether these networks were associated with the maintenance of cognitive function. Methods We included 42 community-dwelling older adults aged >70 years from the MOBILIZE Boston Study. Resting-state fMRI was performed at the study baseline. Participant characteristics, gait speed, Mini-Mental State Examination, and Hopkins Verbal Learning Test (HVLT) were assessed at baseline and at 24-month follow-up. Decliners were identified as individuals with >0.05 meters/second decline in gait speed from baseline to 24 months. Of the 26 decliners and 16 maintainers, decliners exhibited a significant decline in delayed-recall performance on the HVLT over 24 months. Results Controlling for baseline age and multiple comparisons, contrary to initial hypothesis, maintainers exhibited lower baseline primary motor and premotor connectivity (p =.01) within the SMN, and greater baseline ventral visual–supramarginal gyrus connectivity within the FPN (p =.02) compared to decliners. Lower primary motor–premotor connectivity was correlated with maintenance of delayed-recall performance on the HVLT (p =.04). Conclusion These findings demonstrated a potential compensatory mechanism involved in the link between the decline in gait speed and episodic memory, whereby baseline connectivity of the SMN and FPN may underlie subsequent maintenance of gait speed and cognitive function in old age. [ABSTRACT FROM AUTHOR]

Background Myelin loss is a feature of cerebral small vessel disease (cSVD). Although physical activity levels may exert protective effects over cSVD pathology, its specific relationship with myelin content in people living with the cSVD is unknown. Thus, we investigated whether physical activity levels are associated with myelin in community-dwelling older adults with cSVD and mild cognitive impairment. Methods Cross-sectional data from 102 individuals with cSVD and mild cognitive impairment were analyzed (mean age [ SD ] = 74.7 years [5.5], 63.7% female). Myelin was measured using a magnetic resonance gradient and spin echo sequence. Physical activity was estimated using the Physical Activity Scale for the Elderly. Hierarchical regression models adjusting for total intracranial volume, age, sex, body mass index, and education were conducted to determine the associations between myelin content and physical activity. Significant models were further adjusted for white matter hyperintensity volume. Results In adjusted models, greater physical activity was linked to higher myelin content in the whole-brain white matter (R 2change =.04, p =.048). Greater physical activity was also associated with myelin content in the sagittal stratum (R 2change =.08, p =.004), anterior corona radiata (R 2change =.04, p =.049), and genu of the corpus callosum (R 2change =.05, p =.018). Adjusting for white matter hyperintensity volume did not change any of these associations. Conclusions Physical activity may be a strategy to maintain myelin in older adults with cSVD and mild cognitive impairment. Future randomized controlled trials of exercise are needed to determine whether exercise increases myelin content. [ABSTRACT FROM AUTHOR]