NEW ORLEANS — Brachial artery endothelial dysfunction is strongly correlated with subtle neurocognitive abnormalities, primarily in the realm of attention and executive function, in older cardiovascular patients with no clinical evidence of cognitive dysfunction or dementia, Dr. Daniel E. Forman said at the annual meeting of the American College of Cardiology.
“The implication, which I think is very profound, is that cardiovascular disease predisposes to neurovascular changes and thereby to subtle changes in neurocognitive capacities that we don't routinely look at. This raises the question of whether improving vascular health might delay cognitive decline. Executive function changes are common; they're insidious and quite detrimental—and they are potentially avoidable,” said Dr. Forman, a cardiologist at Brigham and Women's Hospital and Harvard Medical School, Boston.
He provided an update on the work of a multidisciplinary team at the hospital exploring the relationship between brachial artery endothelial function and vascular-mediated neurocognitive function.
The premise underlying their work is that vascular-mediated cognitive function depends upon a well-functioning cerebrovascular endothelium, which serves to maintain cerebral perfusion in the face of hemodynamic fluctuations. The availability of the vasodilator nitric oxide in one vascular bed has been shown to correlate with nitric oxide availability in other vascular beds. So impaired endothelial responses in the brachial artery might be expected to be associated with neurocognitive dysfunction secondary to endothelial dysfunction within the cerebral arteries, he explained.
This is indeed what researchers found in their study of 88 patients with mild to moderate cardiovascular disease and no history of neurologic disease, depression, or dementia.
The community-dwelling, independent patients, who averaged 70 years of age, underwent comprehensive neurocognitive testing that assessed global cognitive function, language skills, visual-spatial function, and learning and memory. There was a particular emphasis on test batteries that evaluated executive function—the capacity to control and apply one's mental resources using strategic thinking—which includes attention and psychomotor capabilities.
The patients' mean score on the Mini-Mental State Examination was 28.4, with an average score of 136.9 on the Dementia Rating Scale, underscoring the point that the study population did not have dementia.
Both brachial artery flow-mediated vasodilation as well as nitroglycerin-mediated endothelium-independent vasodilation, as assessed by ultrasound, were found in multiple regression analyses to correlate significantly with measures of attention, executive function, and processing speed, including the Stroop test, the Controlled Oral Word Fluency Test (COWAT), and the Trail-Making Test, Part B.
“The measures of executive function were very predictive of endothelial performance. The COWAT is a test of word-generation capacity, and the Stroop score reflects the ability to discriminate between a color on a page and a word identifying a different color, so you have here a realm of neurocognitive function that has nothing to do with memory. These are people who are arguably normal in terms of dementia but really have some pretty severe deficits,” the cardiologist noted.
The presence of cardiovascular risk factors, including hypertension, diabetes, smoking, and hypercholesterolemia, didn't affect the relationship between brachial artery endothelial function and neurocognitive status, he added.