Carotid artery intima-media thickness and cognition in cardiovascular disease

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Abstract

Background

Increased carotid artery intima-media thickness (IMT) is a non-invasive marker of systemic arterial disease. Increased IMT has been associated with atherosclerosis, abnormal arterial mechanics, myocardial infarction, and stroke. Given evidence of a relationship between cardiovascular health and attention-executive-psychomotor functioning, the purpose of this study was to examine IMT in relation to neuropsychological test performance in patients with a variety of cardiovascular diagnoses.

Methods

One hundred and nine participants, ages 55 to 85, underwent neuropsychological assessment and B-mode ultrasound of the left common carotid artery. IMT was calculated using an automated algorithm based on a validated edge-detection technique. The relationship between IMT and measures of language, memory, visual–spatial abilities and attention-executive-psychomotor functioning was modeled using hierarchical linear regression analyses adjusted for age, education, sex, cardiovascular risk, current systolic blood pressure, and history of coronary artery disease (CAD).

Results

Increased IMT was associated with significantly lower performance in the attention-executive-psychomotor domain (IMT beta =  0.26, p < .01), independent of age, education, sex, cardiovascular risk, current systolic blood pressure, and CAD (F(10,100) = 3.61, p < .001). IMT was not significantly related to language, memory, or visual–spatial abilities.

Conclusions

Our findings suggest that, in patients with cardiovascular disease, IMT may be associated with the integrity of frontal subcortical networks responsible for attention-executive-psychomotor performance. Future studies are needed to clarify the mechanisms by which IMT affects cognition and examine potential interactions between increased IMT and other measures of cardiovascular health such as blood pressure variability, cardiac systolic performance, and systemic perfusion.

Introduction

Increasing evidence suggests that cardiovascular disease is associated with diminished cognitive functioning, even in patients who do not meet criteria for vascular dementia [1], [2], [3], [4]. A new diagnostic category, referred to as vascular cognitive impairment, has been proposed to include these subtle alterations of cognitive ability [5], that nonetheless appear to be associated with higher incidence of dementia later in life, loss of independence, and increased mortality [6]. Because these cognitive changes may be mediated through compromises in the structural and functional integrity of cerebral blood vessels, it is important to define relationships between markers of vessel health and cognition.

In this study, we examined the relationship between increased carotid artery intima-media thickness (IMT) and neuropsychological functioning in a clinically heterogeneous sample of stable outpatients with cardiovascular disease. IMT, as assessed by B-mode ultrasound, is a reliable, non-invasive measure of disease-related arterial wall changes [7]. Though small increases in IMT may be an adaptive response to changes in blood pressure and flow, there is consensus that IMT levels greater than 0.9 mm are indicative of atherosclerotic vascular disease and end organ damage [8]. Atherosclerosis of the large and medium-sized arteries is associated with plaque formation, inflammation, endothelial dysfunction, thrombosis, and acute or chronic luminal obstruction resulting in abnormal blood flow to target organs [9]. By virtue of cerebral architecture and vasculature, the frontal subcortical networks that govern complex attention, executive functioning and cognitive processing speed are particularly susceptible to ischemic damage resulting from blood flow abnormalities [10]. Impairment of attention-executive-psychomotor functions is a hallmark of both vascular dementia and the milder, yet more prevalent category of vascular cognitive impairment [11]. A relationship between IMT specifically and attention-executive-psychomotor test performance, however, has been inconsistently reported in the previous literature. One community-based study reported a significant association between increased IMT and lower visual attention and psychomotor speed for both men and women [12], while another found a similar relationship only in men with carotid plaques [13]. IMT was found to be a good predictor of cognitive decline over time in stroke patients [14] but not in community dwelling elderly [15]. These differences are likely due to the fact that IMT values in community samples are generally well below the accepted cut off of 0.9 mm indicating vascular damage from atherosclerosis [13], [15]. We hypothesized that increased IMT will be related to lower attention-executive-psychomotor performance in patients with cardiovascular disease because they can be expected to exhibit pathological arterial wall changes at rates much higher than those found in the general population.

Section snippets

Study sample

Participants between the ages of 55 and 85 were recruited from cardiology outpatient clinics, cardiac rehabilitation programs, and community fliers in the Providence, RI area. Volunteers were screened for participation if they had a documented history of at least one of the following: a diagnosis of coronary artery disease (CAD), angina pectoris, previous myocardial infarction (MI), heart failure, cardiac surgery, arrhythmia or hypertension. Patients were excluded from the study if they had a

Results

The raw cognitive test scores for the sample are summarized in Table 2. The fully adjusted models successfully predicted the level of cognitive performance in all five domains: global (F(9,100) = 2.40, p < .05), language (F(9,100) = 4.62, p < .001), visual–spatial (F(9,100) = 2.11, p < .05), memory (F(9,100) = 2.44, p < .05), and attention-executive-psychomotor (F(9,100) = 3.66, p < .001).

Older age was significantly associated with poorer global cognitive functioning (beta =  .23, p < 0.05), weaker language skills

Discussion

The present study found that increased carotid artery IMT was associated with lower attention-executive-psychomotor test performance in non-demented patients with a variety of cardiovascular diagnoses. The effect was independent of age, sex, education, cardiovascular risk, current systolic blood pressure, and history of CAD. Our results are consistent with findings demonstrating a significant relationship between cognition and other measures of large artery structure and function such as pulse

Acknowledgement

The authors thank Drs. Michael Cohen and J. Andrew Taylor for their help in the development of the automated edge-detection software used for calculating IMT, and Dr. Makoto Ono for his help with coding the medication data.

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  • Cited by (0)

    This work was supported by National Institute of Health grants AG017975 (RAC), AG 026850 (KFH), HL074568 (JG), MH065857 (RHP), AG022773 and HD043444 (ALJ).

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