P3‐284: Lower Cardiac Index Levels Relate to Reduced Cerebral Blood Flow Values in Older Adults with Normal Cognition and Mild Cognitive Impairment: the Vanderbilt Memory and Aging Project
Year: 2016
Type: article
Study design: Observational Study
Abstract: Mechanisms underlying reported associations between lower cardiac index and smaller brain volume, increased white matter hyperintensities, worse cognitive performance and incident dementia are not well understood. We hypothesized that lower systemic cardiac index is associated with lower cerebral blood flow (CBF) among older adults without dementia. Participants with normal cognition and mild cognitive impairment (n=318, 73±7, 59% male) were drawn from the Vanderbilt Memory & Aging Project, a case control longitudinal study. Cardiac index ((stroke volume x heart rate)/body surface area, L/min/m) was quantified from echocardiography. CBF, the rate of blood delivery to tissue (mL blood/100g tissue/min), was assessed with pseudo-continuous arterial spin labeling MRI. Linear regression models with ordinary least square estimates related cardiac index to CBF regions of interest (ROIs) determined by multi-atlas segmentation adjusting for Framingham Stroke Risk Profile (including age, sex, systolic blood pressure, anti-hypertensive medication usage, diabetes, left ventricular hypertrophy, atrial fibrillation, and prevalent cardiovascular disease (CVD)), race, education, cognitive diagnosis, apolipoprotein E4 status, and corresponding ROI tissue volume. Lower cardiac index levels related to lower CBF values in the temporal lobe and prefrontal cortex but not in the occipital or parietal lobes. Specifically, lower cardiac index was associated with lower CBF in right and left hippocampi (p<0.004), right parahippocampal gyrus (p=0.002), right and left superior temporal gyri (p<0.01), right and left medial temporal gyri (p<0.001), right and left inferior temporal gyri (p<0.004), right and left fusiform gyri (p<0.01), right and left anterior cingulate gyri (p<0.002), right and left medial frontal cortex (p<0.0004), and right and left inferior frontal gyri (p<0.006). When models were repeated excluding participants with prevalent CVD and atrial fibrillation, findings were not attenuated. Among older adults free of dementia, systemic hemodynamics may affect cerebral hemodynamics in a regionally specific pattern independent of concurrent vascular risk factors (e.g., hypertension, diabetes) and prevalent CVD. Such compromises in cerebral circulation control may contribute to amyloid aggregation or clearance, neuronal injury, and cerebrovascular damage. Further investigation into the mechanisms linking cardiac index, regional CBF, and corresponding brain health consequences is merited. Funding: IIRG-08-88733, R01-AG034962, K24-AG046373, UL1-TR000445, K23- AG045966, K23-AG048347, K12-HD043483.
Source: Alzheimer s & Dementia
Institution: Vanderbilt University
Language: English
Subfield: Psychiatry and Mental health
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2535209162