Carotid Stenosis Tied to Cognitive Decline as Well as Stroke

Patients who have blockages in the carotid arteries are at risk not only for stroke but possibly for cognitive impairment as well, according to the results of a new study.

“We have fairly compelling evidence that there is a decline in cognitive function associated with blockages in the carotid arteries in asymptomatic patients,” principal investigator Brajesh Lal, MD, Professor of Vascular Surgery at the University of Maryland School of Medicine in Baltimore told ConsultantLive in an exclusive interview. “No one has asked about what happens to the way the brain functions-thinks, processes information, remembers, recollects new information-when blood flow is restricted from stenosis.”

A neuropsychologist at the University of Maryland, Moira C. Dux, PhD, will present the details of the study at the American Academy of Neurology annual meeting in Philadelphia.

The study involved 67 persons with asymptomatic carotid stenosis who had a 50% reduction in the diameter of the artery, and 60 persons with vascular risk factors, including diabetes mellitus, hypertension, hypercholesterolemia, and coronary artery disease, with no stenosis. The patients underwent extensive testing for overall thinking abilities and for specific aspects of thinking, such as processing speed, learning, memory, decision making, and language.

The stenosis group performed significantly worse on the overall memory and thinking tests, as well as on tests for motor and processing speed, and learning and memory. Language scores did not differ between the 2 groups.

“We have demonstrated, for the first time, that carotid stenosis without a neurologic deficit is not necessarily ‘asymptomatic’ and is associated with greater cognitive impairment compared to patients with similar risk factors but no stenosis,” said Dr Lal.

Two potential mechanisms are restriction of blood flow caused by the stenosis and microinfarction from the release of microparticles, Dr Lal stated. “Microparticles could lodge in nonexpressive areas of the brain, which become infarcted, and then be expressed as cognitive impairment,” he said. “We are now looking at transcranial flow within the brain, microembolization from plaque, and microinfarction and brain injury in these patients.” The researchers also plan to monitor these patients, average age 60 years, for at least another 2 years to assess their risk of stroke.

Every patient with carotid stenosis has significant atherosclerosis and should be receiving aspirin and statin therapy, Dr Lal said. “With these data, I will start asking my carotid stenosis patients, how has your memory been? Do you have trouble thinking? If they have any suggestion of cognitive impairment, I will refer them to a neuropsychologist,” he said, adding “I don’t think I can recommend carotid endarterectomy yet.”

Dr Lal has preliminary data from a previous study that show using both surgery and stenting for carotid artery stenosis leads to a net improvement in cognitive function.

“From 8 to 15 million US patients have asymptomatic carotid artery stenosis. I anticipate a large number of follow-up studies searching for causes and the best treatment options for this newly identified morbidity associated with carotid narrowing,” Dr Lal said. “Once we identify the mechanism, we potentially can mount a clinical trial comparing cognitive rehabilitation versus revascularization.”