A groundbreaking study presented at the American Stroke Association's International Stroke Conference 2026 has challenged conventional wisdom. The research, led by Dr. Ronald M. Lazar, a renowned neurologist and neurobiologist, suggests that improving blood flow to the brain by treating a narrowed neck artery may not lead to enhanced cognitive skills. This finding is a game-changer, especially for those with carotid artery stenosis, a condition often treated with procedures like carotid endarterectomy or stenting.
The CREST-2 trial, a comprehensive study involving over 2,000 adults, compared different treatment approaches for carotid stenosis, a condition where the carotid arteries in the neck become narrowed due to plaque buildup. The study's unique design included a "cognitive core" component, assessing cognitive performance before and after treatment over a period of up to four years.
Dr. Lazar and his team found that while there was an association between carotid stenosis and lower cognitive function scores, treating the condition with procedures to restore blood flow did not result in improved thinking or memory skills. This was true even for participants with the lowest cognitive function at the study's start, who were expected to benefit the most from these treatments.
"The brain's cells need a steady flow of oxygen-rich blood. When blood vessels are blocked or narrowed, the brain doesn't receive enough oxygen, impacting the neurons' ability to function properly, which can lead to changes in cognitive skills," Dr. Lazar explained.
However, the study also revealed that cognitive decline over time could be a signal that the treatment plan needs re-evaluation and potential adjustment. This finding is particularly significant as it provides a new perspective on how healthcare professionals should counsel patients about the benefits and limitations of stenting or surgery to open narrowed carotid arteries.
"The results of this study challenge the notion that treating carotid stenosis will automatically improve cognition. Healthcare professionals must now consider a more nuanced approach, focusing on the individual's specific needs and the potential impact of other factors on cognitive function," Dr. Lazar emphasized.
The study's limitations include the fact that all cognitive tests were conducted over the phone, limiting the assessment of visuo-spatial skills and executive functions. Additionally, the study only included English-speaking participants, so the results may not be applicable to other populations.
Dr. Mitchell Elkind, the American Heart Association's Chief Science Officer for Brain Health and Stroke, commented on the study's findings, emphasizing the complexity of cognitive decline associated with aging and the need for further research to address this issue.
"The CREST-2 study provides valuable insights into the relationship between carotid stenosis and cognitive function, but it also highlights the need for a more holistic approach to treating cognitive decline. While restoring blood flow through large vessels is important, it's just one piece of the puzzle. We must also consider other factors like inflammation, neurodegeneration, and small vessel disease," Dr. Elkind said.
The study's preliminary findings have sparked further discussion and research, with the American Heart Association continuing to support studies in these important areas to improve brain health and reduce the risk of dementia.
