Estimated means and 95% confidence intervals for total, structural, and load-dependent changes in carotid artery Peterson’s elastic modulus (PEM) over 10 years of aging by age groups. Older individuals (75–84, yellow bars) had greater rates of total, structural, and load-dependent stiffening. ANCOVA model co-variates were: sex, race/ethnicity, education level, income, smoking status, diabetes mellitus status, systolic blood pressure, total cholesterol, HDL cholesterol, BMI, antihypertensive medication, and lipid lowering medication.