Low Cardiac Index is Associated with Incident Dementia and Alzheimer's Disease: The Framingham Heart Study
Background—Cross-sectional epidemiological and clinical research suggest lower cardiac index is associated with abnormal brain aging, including smaller brain volumes, increased white matter hyperintensities, and worse cognitive performances. Lower systemic blood flow may have implications for dementia among older adults.
Methods and Results—1039 Framingham Offspring Cohort participants free from clinical stroke, transient ischemic attack, or dementia formed our sample (69±6 years; 53% women). Multivariable-adjusted proportional hazard models adjusting for Framingham Stroke Risk Profile score (age, sex, systolic blood pressure, anti-hypertensive medication, diabetes, cigarette smoking, cardiovascular disease [CVD] history, atrial fibrillation), education, and apolipoprotein E4 status related cardiac MRI-assessed cardiac index (cardiac output/body surface area) to incident all-cause dementia and Alzheimer's disease (AD). Over the median 7.7 year follow-up period, 32 participants developed dementia, including 26 cases of AD. Each one standard deviation unit decrease in cardiac index increased the relative risk of both dementia (HR=1.66; 95% confidence intervals [CI], 1.11-2.47; p=0.013) and AD (HR=1.65; 95% CI, 1.07-2.54; p=0.022). Compared to normal cardiac index, individuals with clinically low cardiac index had a higher relative risk of dementia (HR=2.07; 95% CI, 1.02-4.19; p=0.044). If participants with clinically prevalent CVD and atrial fibrillation were excluded (n=184), individuals with clinically low cardiac index had a higher relative risk of both dementia (HR=2.92; 95% CI, 1.34-6.36; p=0.007) and AD (HR=2.87; 95% CI, 1.21-6.80; p=0.016) compared to individuals with normal cardiac index.
Conclusions—Lower cardiac index is associated with an increased risk for the development of dementia and AD.
- Received August 25, 2014.
- Revision received February 9, 2015.
- Accepted February 11, 2015.