Intracranial atherosclerosis on 7T MRI and cognitive functioning – the SMART-MR study

1. Among patients with vascular disease, high burden of atherosclerotic lesions in the posterior circulation as well as the posterior cerebral artery was associated with poorer memory and executive functioning.

Evidence Rating Level: 2 (Good)

The individual and societal burden of dementia continues to rise as the global population, on average, grows older. Though it is well known that cerebrovascular disease as a result of intracranial atherosclerosis (ICAS) can contribute to dementia and cognitive decline, less is known about this relationship with regards to premorbid cognitive functioning and the effect of artery-specific lesions. This prospective cohort study used 7 tesla (7T) vessel wall-MRI to explore the association between ICAS and cognitive function among 130 patients (mean [SD] age = 68 [9] years, 88% male) with known vascular disease. Each patient’s neuropsychological status was assessed with a variety of tests, and individual testing scores were averaged to yield a composite Z-score. Imaging revealed that among the cohort, the average ICAS burden for the total circulation (ICASTC) was 8.5±5.7 lesions, for the anterior circulation (ICASAC) 5.3±3.2 lesions, and for the posterior circulation (ICASPC) 3.8±3.0 lesions. No significant association between ICASTC and memory was found (b = -0.02 per +1 lesion, 95% CI -0.05 to 0.00, where b is a linear regression coefficient representing the difference in Z-score per one lesion increase in ICAS burden), even after controlling for age, sex, education level, and reading ability. However, a significant association between ICASPC and memory was observed (b = -0.06 per +1 lesion, 95% CI -0.10 to -0.01). Additionally, when looking at individual arteries, ICAS burden in the posterior cerebral artery (ICASPCA) was associated with significant decline in both memory (b = -0.13 per +1 lesion, 95% CI -0.24 to -0.02) and executive function (b = -0.09 per +1 lesion, 95% CI -0.17 to -0.01). Non-significant associations between ICAS burden in the anterior cerebral artery (ICASACA) and decline in memory and executive function were observed. No significant associations were seen for the middle cerebral, internal carotid, vertebral, or basilar arteries. Overall, this study showed that among patients with a history of vascular disease, high ICAS burden in the posterior circulation as well as the posterior cerebral artery was associated with poorer memory and executive function. These findings may help inform understanding of how atherosclerosis of specific cerebral vessels contributes to the development of dementias.

Click to read the study in Neurology

Image: PD

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