Rizwan Kalani, MD

The evidence linking atherosclerotic vascular risk factors and cognitive impairment continues to expand. Prior work has suggested that carotid intima-media thickness (CIMT) is a risk factor for cognitive decline, including in patients with Alzheimer’s disease. In this study, Moon et al. evaluated evaluated the association between cardiovascular risk factors–including CIMT–and future risk of mild cognitive impairment (MCI) or dementia in older people.

This was done as part of the KLoSHA study (Korean Longitudinal Study on Health and Aging), a population-based prospective cohort study. Three hundred forty-eight subjects, without pre-existing dementia, with available baseline cardiovascular risk factor data, were enrolled and completed a 5 year follow-up evaluation that included cognitive assessment. The mean age (± standard deviation) was 71.7 (± 6.3) years at time of enrollment and 51% were males. Korean versions of the following cognitive tests were completed: 1) consortium to establish a registry for Alzheimer’s disease clinical assessment battery; 2) mini international neuropsychiatric interview; 3) lexical fluency testing, and; 4) digit span. Education and mood were also assessed in these older adults. Cardiovascular risk factors (tobacco exposure, alcohol consumption, body mass index, waist circumference, blood pressure, plasma fasting glucose, plasma insulin, insulin resistance, vitamin B12, cholesterol, renal and hepatic function) were assessed. CIMT (as measured by ultrasound), carotid-femoral pulse wave velocity (PWV) index, and ankle-brachial index (ABI) were recorded.

At time of enrollment, 278 subjects were cognitively normal and 70 had MCI. After the study period, 56 progressed to MCI (50) or dementia (6); 225 of the original cognitively normal 278 individuals remained the same. At baseline, the progression group had higher age, shorter education period, and higher prevalence of hypertension. CIMT was greater in the progression group than in the non-progression group (0.81±0.11 vs 0.77±0.13mm, p=0.023); carotid artery plaque formation was also seen more frequently in the progression group (78.6% vs 63.7%, p=0.02). Other cardiovascular risk factors were not significantly different between the groups. Baseline CIMT was independently associated with development of MCI or dementia in multivariate logistic regression analyses (adjusting for age, education period, hypertension, cognitive parameters, and mood). It was also independently associated with development of MCI from normal cognition. CIMT was greater in cognitively normal subjects who developed MCI compared to those who remained normal at follow-up evaluation (0.82±0.11 vs 0.77±0.14mm, p=0.021). Similarly, carotid artery plaque formation was observed more frequently among those who developed MCI from a normal cognitive status compared to those who remained normal (80.0% vs 63.6%, p=0.026).

This study reaffirmed an association between baseline CIMT and carotid plaque formation with cognitive decline in older individuals. CIMT was superior in predicting clinically significant cognitive decline compared to other atherosclerotic markers (PWV, ABI) and cardiovascular risk factors. Major limitations of this report include the observational design, the fact that only a small number of individuals developed dementia in this study, and low follow-up rate from a significantly larger cohort that was originally enrolled. Future work should include longitudinal assessment of CIMT and cognition over time.