Carotid Artery Atherosclerosis, MRI Indices of Brain Ischemia, Aging, and Cognitive Impairment

Abstract

Background and Purpose— Carotid atherosclerosis has been associated with increased risk of stroke and poorer cognitive performance in older adults. The relation of carotid atherosclerosis to cognitive impairment and MRI indices of ischemia and aging in midlife is less clear. Methods— We studied 1975 Framingham Offspring Study participants free of stroke and dementia with available carotid ultrasound, brain MRI, and neuropsychological testing. We related common and internal carotid artery intima-media thickness and internal carotid stenosis to large white matter hyperintensity (>1 SD above age-specific mean), total brain volume, hippocampal volume, silent cerebral infarcts, and neuropsychological measures of verbal memory, executive function, and nonverbal memory measures. Results— We observed that internal carotid artery intima-media thickness, but not common carotid artery intima-media thickness, was associated with higher prevalence of silent cerebral infarcts (OR, 1.21; 95% CI, 1.03–1.43; P <0.05), large white matter hyperintensity (OR, 1.19; 95% CI, 1.03–1.38; P <0.05), lower total brain volume (−0.05 per SD; P <0.05), and poorer performance in verbal memory (−0.06 per SD; P <0.05) and nonverbal memory measures (−0.08 per SD; P <0.01), but not with hippocampal volume. Internal carotid stenosis ≥25% was associated with a higher prevalence of large white matter hyperintensity (adjusted OR, 1.77; 95% CI, 1.25–2.53) and lower total brain volume (−0.11 per SD; P =0.042) but not with silent cerebral infarcts or hippocampal volume. Internal carotid stenosis ≥50% was associated with higher prevalence of silent cerebral infarcts (OR, 2.53; 95% CI, 1.17–5.44), large white matter hyperintensity (OR, 2.35; 95% CI, 1.08–5.13), and poorer performance on executive function (−0.39 per SD; P <0.05), but not with total brain volume or hippocampal volume. Conclusions— Carotid atherosclerosis markers were associated with MRI indices of brain ischemia and aging and with cognitive impairment in a community-based sample of middle-aged adults. Our data suggest that internal carotid artery intima-media thickness may be a better marker for cognitive impairment than common carotid artery intima-media thickness.