When oxygenated blood needs to squeeze through a narrowed space to get to the brain -- a condition called asymptomatic carotid stenosis -- mental performance may suffer, even in the absence of stroke, a new study suggests.
In patients with diabetes, high blood pressure, cardiovascular disease and worrisome cholesterol readings, physicians may test for buildup of plaque in the carotid artery, peering into the vessel at the nape of the neck with ultrasound. As plaque either builds up or breaks off and lodges deeper into the brain's vasculature, it can cause a stroke, a major cause of death and disability.
But research to be presented next week at the American Academy of Neurology's 66th annual meeting suggests that well before stroke occurs, patients found to have carotid stenosis may already suffer ill effects from carotid artery narrowing.
A study compared the learning and memory skills of 67 subjects with 50% reduction in the diameter of the carotid artery to 60 subjects with normal blood flow through the carotid vessel. On tests that captured overall thinking skills and memory, those with carotid artery stenosis fared much more poorly than did those without.
In more specific tests of mental performance, the latest research found that mental processing speed and motor response were, on average, significantly worse in those with narrowed carotid arteries. Language scores did not differ between the two groups.
Dr. Brajesh K. Lal, the lead investigator of the study and a neurologist with the Veterans Affairs Maryland Health Care System in Baltimore, said that if larger studies bear out his findings, physicians may screen earlier and act more aggressively to treat carotid artery narrowing.
Stroke has been "the only harm that these blockages were thought to cause to patients," said Lal. But if cognitive impairment were found to be a direct result of that narrowing, Lal said, physicians might consider whether medication or even surgery might be effective at reducing the plaque buildup, or whether cognitive rehabilitation might improve thinking skills in patients with such buildup.