Carotid atherosclerosis, vascular risk factors and relation to cognitive test results : the Tromsø study 1994-2008.

Abstract

The prevalence of dementia and cognitive impairment is rising worldwide as the number of elderly people increases in most countries. Vascular risk factors and carotid artery atherosclerosis have in some epidemiological studies been associated with increased risk of cognitive decline. The carotid artery is essential for blood supply to the brain, but is also vulnerable to atherosclerosis. The degree of atherosclerosis in the carotid artery can easily be measured by ultrasonography.

The population-based Tromsø study, with repeated screening surveys of the Tromsø population, has made it possible to follow participants prospectively. Repeated carotid ultrasound scanning and cognitive test assessments have provided a unique opportunity for assessing change in atherosclerosis and change in cognitive test scores. In this study we assessed the impact of different vascular risk factors on scores in three cognitive tests after 7 years of follow-up, and studied if carotid atherosclerosis and progression of atherosclerosis were independent risk factors for lower cognitive test scores and cognitive decline in a middle–aged stroke-free population.

We found that diabetes, smoking and systolic blood pressure were consistent and independent risk factors for lower cognitive test results after 7 years follow-up in both genders. Physical inactivity was associated with lower scores in women. Carotid atherosclerosis measured as total plaque area and number of plaques predicted lower scores on the verbal memory test 7 years later, whereas the average of plaque scores, measured at baseline and at follow-up, was associated with lower scores on all the cognitive tests in this study. Progression of carotid plaques over 7 years was associated with lower scores on the digit symbol coding test and the tapping test. We found no association between plaque scores and cognitive decline from 7 to 13 years of follow-up.