A new study has found that improving blood flow to the brain by opening a narrowed neck artery may not help patients think more clearly.
The research was shared at the American Stroke Association’s International Stroke Conference 2026.
The study looked at people with carotid artery stenosis, a condition where plaque builds up in the neck arteries and reduces blood flow to the brain.
Treatments usually include taking medications and making lifestyle changes.
In more serious cases, doctors may recommend a surgery called carotid endarterectomy or a procedure to insert a stent to open the artery.
Researchers from the University of Alabama at Birmingham (UAB), led by Dr. Ronald Lazar, wanted to know if any of these treatments could also improve thinking and memory skills.
Dr. Lazar said that whether patients get surgery, a stent, or just medical therapy, they should not expect better brain function as a result.
The study is part of the large CREST-2 trial, which compares different treatments for carotid stenosis. One part of this study focused specifically on how these treatments affect thinking over time. This is the first major study to include cognitive function as a main result.
Dr. Lazar explained that the brain needs a steady flow of blood to work properly. When blood flow is reduced, it can lead to problems with attention, memory, and decision-making.
In 2021, researchers had found that people with severe carotid artery narrowing, but no symptoms, scored lower on memory tests compared to others with similar health backgrounds. That led them to believe that restoring blood flow might improve cognitive skills.
However, after following patients for nearly three years, the team found no difference in thinking or memory between those who had a procedure and those who only got medical therapy. Even patients who started the study with low cognitive scores did not show improvement after treatment.
Still, the study did show that patients who had a stroke during the trial had worse thinking abilities afterward. This shows the tests can detect real brain changes.
These findings may change the way doctors talk to patients about carotid treatments. Dr. Lazar said, “Doctors should no longer tell patients that treating carotid stenosis will help their thinking.” But if a patient’s thinking gets worse over time, it might be a sign that their treatment plan should be reviewed.
The study couldn’t prove whether low blood flow alone causes thinking problems. It’s possible that small particles from the plaque in the artery may also travel to the brain and cause damage. The team plans to study this more in the future.
The study had some limits. All cognitive tests were done by phone, so they couldn’t test visual skills or some types of thinking. Also, only English-speaking patients were included, so the results may not apply to everyone.
Dr. Mitchell Elkind from the American Heart Association said that while surgery can lower stroke risk, it may not help with memory or thinking. He added that cognitive decline in aging is complicated, and fixing blood flow alone may not solve it. More research is needed to better understand and prevent memory loss and dementia.
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