BACKGROUND Greater hippocampal volume is observed in healthy older adults after short-term structured exercise. Whether long-term exposure to real-world physical activity (PA) programs has similar effects for sedentary older adults with impaired mobility and comorbid conditions is not known. HYPOTHESIS A long-term moderate intensity regimen of PA is related to larger volume of the hippocampus in older adults at risk for mobility disability. We further explore whether these associations are modified by factors known to be related to dementia. METHODS Twenty-six sedentary adults at risk for mobility disability participated in a 24-month randomized intervention program of physical activity (PA, n=10, age: 74.9 years, 7 women) or health education (HE, n=16, age: 76.8 years, 14 women). Volumes of total hippocampus, dentate gyrus and cornu ammonis were measured at baseline and at 24-month follow-up using 7 Tesla MRI. Between-group volumetric differences at 24-months were adjusted for sessions attended and baseline volumes. The contribution of each dementia-related factor was tested separately for education, APOE, diabetes, cardiovascular diseases, white matter hyperintensities and brain atrophy. RESULTS Between-group differences were significant for left hippocampus, left cornu ammonis and right hippocampus. Adjustment for regional baseline volume attenuated the associations to statistically non-significant for right hippocampus and left conru ammonis; associations for left hippocampus were robust for all adjustments. Results were similar after adjustment for dementia-related factors. CONCLUSIONS In this group of sedentary older adults there was a hippocampal response to a long-term program of moderate-intensity PA. Future studies should examine whether hippocampal response could explain the beneficial effects of PA on cognition for vulnerable older adults.
In older adults, depressive symptoms are associated with lower quality of life, high morbidity and mortality. This study aims to identify brain magnetic resonance imaging (MRI) features associated with late-life depressive symptoms in the population. Older community-dwelling adults (n = 314) from the Health ABC study underwent brain MRI. Logistic regression was used to characterize the relationships between depressive symptoms (Center for Epidemiologic Studies of Depression scale, CES-D) and the following whole-brain variables: white matter hyperintensity (WMH) burden, fractional anisotropy (FA), and gray matter volume (GMV). Analyses examining possible regional differences between the CES-D groups controlled for Modified Mini-Mental State Examination score and diabetes status. The relative importance of localization of the markers was examined by comparing the distribution of significant peaks across the brain. Each whole-brain variable showed loss of integrity associated with high CES-D. For GMV, the odds ratio (OR)=0.84 (95% confidence interval (CI) 0.74, 0.96); for FA, OR=0.714 (95% CI 0.57, 0.88); for WMH, OR=1.89 (95%CI 1.33, 2.69). Voxel-wise analyses and patterns of peak significance showed non-specific patterns for white matter measures. Loss of GMV was most significant in the bilateral insula and anterior cingulate cortex. This study supports a cerebrovascular pattern for depressive symptoms in older adults. The localization of gray matter changes to the insula, a watershed area and a hub of affective circuits, suggests an etiological pathway from ischemia to increased depressive burden.
BACKGROUND AND PURPOSE:Traditional neuroimaging markers of small-vessel disease focus on late-stage changes. We aimed to adapt a method of venular assessment at 7T for use in older adults. We hypothesized that poorer venular morphologic characteristics would be related to other small-vessel disease neuroimaging markers and a higher prevalence of small-vessel disease-Alzheimer disease risk factors.
OBJECTIVE Psychomotor slowing is a common cognitive complication in type 1 diabetes (T1D), but its neuroanatomical correlates and risk factors are unclear. In non-diabetic adults, smaller gray matter volume (GMV) and presence of white matter hyperintensities (WMH) are associated with psychomotor slowing. We hypothesize that smaller GMV in prefronto-parietal regions explains T1D-related psychomotor slowing. We also inspect the contribution of microvascular disease and hyperglycemia. METHODS GMV, WMH, and glucose levels were measured concurrently with a test of psychomotor speed (Digit Symbol Substitution Test, DSST) in 95 adults with childhood-onset T1D (mean age/duration=49/41 years) and 135 similarly-aged non-T1D adults. Linear regression models tested associations between DSST and regional GMV, controlling for T1D, sex, and education; a bootstrapping method tested whether regional GMV explained between-group differences in DSST. For the T1D cohort, voxel-based and a priori regions-of-interest methods further tested associations between GMV and DSST, adjusting for WMH, hyperglycemia, and age. RESULTS Bilateral putamen, but not other regions, significantly attenuated DSST differences between the cohorts (bootstrapped unstandardized indirect effects: −3.49, −3.26; 95% confidence limits [−5.49, −1.80], [−5.29 −1.44], left and right putamen, respectively). Among T1D, DSST was positively associated with GMV of bilateral putamen and left thalamus. Neither WMH, hyperglycemia, age, nor other factors substantially modified these relationships. CONCLUSIONS For middle-aged adults with T1D and cerebral microvascular disease, GMV of basal ganglia may play a critical role in regulating psychomotor speed, as measured via DSST. Studies to quantify the impact of basal ganglia atrophy concurrent with WMH progression on psychomotor slowing are warranted.
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