News · Brain & Mental Health
Carotid stenting or surgery did not improve memory or thinking in the CREST-2 trials
Narrowed neck arteries have been linked to poorer thinking, and some hoped that opening them would help. In two large trials, people who had the procedures did no better on memory tests than those on medicines alone.
- Two randomized trials of 2,165 US patients with severe carotid artery narrowing but no symptoms.
- Patients had stenting or surgery plus intensive medicines, or intensive medicines alone.
- Memory and thinking scores were no better with either procedure over up to four years.
- Everyone received intensive treatment of blood pressure, cholesterol and other risk factors.
- The trials' separate stroke results, not memory, remain the main basis for choosing a procedure.
Many older adults have narrowing in the large arteries of the neck without ever having a stroke. Studies have linked this narrowing to poorer memory and thinking, and some doctors hoped that opening the arteries might protect the brain in more ways than one.
Two large trials known as CREST-2 (the Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis Trials) put that to the test. The results, in JAMA (the Journal of the American Medical Association), show no gain in memory or thinking from stenting or surgery over up to four years.
What carotid artery stenosis is
MedlinePlus explains that your carotid arteries are two large blood vessels in your neck that carry blood to the brain. In carotid artery disease, they become narrow or blocked, usually because of a buildup of fatty plaque.
The same source notes that carotid artery disease is serious because it can block the blood flow to your brain, leading to a stroke. It often causes no symptoms until the narrowing is severe. Treatments include medicines, surgery to remove the plaque, and stenting.
How the CREST-2 cognition trials worked
The CREST-2 trials enrolled patients 35 or older with narrowing of 70% or more in a carotid artery but no symptoms. One trial compared stenting plus intensive medical treatment with intensive medical treatment alone. The other compared surgery to remove the plaque, known as endarterectomy, with the same medical treatment alone.
Among 2366 US study patients, 2165 (91.5%) participated in cognitive assessments. They took five tests of learning, memory, planning, attention and speed by telephone, before treatment and each year for up to four years. The testers did not know which treatment each person had.
What happened to memory and thinking
Neither procedure made a measurable difference. There were no treatment-related differences in the fully adjusted estimated composite z scores at 4 years in either trial. The gaps between groups were tiny, far smaller than the difference the researchers had set in advance as meaningful.
No single test showed a benefit either. Scores on learning, memory, planning, attention and speed were similar whether people had a procedure or relied on medicines alone.
Why the carotid finding matters
Carotid narrowing is common in older adults, and a procedure is a big decision with its own risks. If stenting or surgery had also protected memory, that would have been a strong extra reason to have one.
The authors conclude that revascularization with either stenting or endarterectomy did not significantly improve cognitive function at up to 4 years of follow-up. That removes one possible argument for a procedure, though it says nothing about the main reason to consider one, which is preventing strokes.
What the CREST-2 memory results cannot show
The average follow-up was a little over two years, so the trials cannot rule out effects that take longer to appear. Testing by telephone is practical but less detailed than face-to-face assessment.
All patients received intensive treatment of blood pressure, cholesterol and other risk factors, which may itself protect the brain. The results apply to people with narrowing but no symptoms, not to those who have already had a stroke or mini-stroke.
What this changes for people with carotid narrowing
For people told they have carotid narrowing without symptoms, the decision about a procedure should rest on stroke risk, not on hopes of sharper memory. The trials’ separate reports on stroke are the place to start that conversation with a specialist.
Whatever the choice, controlling blood pressure and cholesterol, not smoking and staying active remain the foundation of care for narrowed arteries.
People also ask
What did the trials find?
At 4 years, fully adjusted composite cognitive z scores did not differ in either trial. In the stenting trial the between-group difference was 0.03 (95% CI -0.09 to 0.15), and in the endarterectomy trial 0.02 (95% CI -0.09 to 0.14), well below the 0.50 standard deviation set as the smallest meaningful difference. No individual cognitive test differed.
What is carotid artery stenosis?
Narrowing of the carotid arteries, the two large blood vessels in the neck that supply the brain, usually caused by a buildup of fatty plaque.
What does asymptomatic mean here?
The patients had severe narrowing, 70% or more, but had not had a stroke or mini-stroke from it.
What were the procedures?
Carotid endarterectomy is surgery to remove plaque from the artery. Carotid stenting uses a balloon and a mesh tube to open the artery from inside.
Does this mean the procedures are useless?
No. This paper looked only at memory and thinking. Whether the procedures prevent strokes was the trials' main question, reported separately.
What should someone with carotid narrowing do?
Discuss the options with a specialist, including the stroke results of these trials, and keep blood pressure, cholesterol and other risk factors under control. This is general information rather than medical advice.