- Over the last few years, research has shown a potential link between cardiovascular health and brain health.
- Past studies have linked cardiovascular conditions like heart failure to an increased risk for dementia.
- A new study found even minor cardiac dysfunction could possibly predict microscopic tissue deterioration in the brain regions closely linked to Alzheimer’s disease.
Over the last few years, research has shown a potential link between cardiovascular health and brain health.
“Heart health is one of those potentially modifiable areas,” Xia Zhang, a doctoral researcher at the Max Planck Institute for Human Cognitive and Brain Sciences in Germany, told Medical News Today.
“Cardiac function is already measured in routine clinical care, so if we better understand how heart dysfunction is related to brain changes, we may eventually be able to identify people who need closer monitoring or earlier prevention,” Zhang explained.
She is the lead author of a new study published in JNeurosci – The Journal of Neuroscience which found that even minor cardiac dysfunction, such as people without doctor-diagnosed heart failure, could predict microscopic tissue deterioration in the brain regions closely linked to a type of dementia known as Alzheimer’s disease.
For this study, researchers tracked 73 participants from the Leipzig Heart Study for about 3.5 years. Study participants had an average age of about 55, and included both people with diagnosed heart failure and those without a heart failure diagnosis, but suspected coronary artery disease.
“The brain depends heavily on stable blood flow and oxygen delivery,” Zhang explained. “If the heart is not pumping efficiently, even subtly, the brain may be affected over time.“
“Previous studies have shown that people with heart failure often have a higher risk of cognitive problems. But we wanted to ask an earlier question: Does the heart–brain link begin before obvious clinical heart failure, and before obvious brain shrinkage is detectable on conventional structural imaging? That is why we focused on gray matter microstructure, which may capture more subtle tissue-level changes.”
– Xia Zhang
“Specifically, we examined whether routine cardiac measures, such as ejection fraction and NT-proBNP, could predict gray matter microstructural changes years later, and whether those brain changes helped explain later memory performance,” she continued.
At the study’s conclusion, researchers found that even minor cardiac dysfunction, such as that found in study participants without fully diagnosed heart failure, could predict the formation of microscopic tissue degradation in the brain regions closely linked to Alzheimer’s disease.
Zhang said the significance of this finding is that the brain may be vulnerable to cardiac dysfunction earlier than we usually recognize clinically.
“In our study, subtle reductions in cardiac pumping function were already associated with later brain microstructural changes even in patients who did not yet meet clinical criteria for heart failure,” she explained. “The affected regions are important for memory and are also known to be vulnerable in Alzheimer’s disease.”
“Importantly, these microstructural brain changes also helped explain the link between poorer cardiac function and later memory decline,” she continued. “However, because we did not measure Alzheimer’s-specific pathology such as amyloid or tau, we cannot conclude from this study that these patients were developing Alzheimer’s disease.”
Zhang said that the ability to track brain microstructural integrity may potentially offer a new diagnostic avenue for doctors when looking for signs of cognitive issues, but not yet as a routine clinical test.
“Our findings suggest that gray matter microstructural integrity may be a sensitive way to detect subtle brain changes before obvious brain shrinkage or clinical dementia becomes apparent,” she detailed. “At the same time, this needs much more validation. Mean diffusivity is promising, but it is not yet a standard diagnostic marker for cognitive problems in cardiac patients.”
Zhang said the key next step for this research is replication in larger cohorts with repeated follow-up, so researchers can track cardiac function, brain microstructure, and cognition over time more precisely.
“It will also be important to include Alzheimer’s disease biomarkers, such as amyloid and tau, to test whether these cardiac-related brain changes are independent of, overlapping with, or interacting with Alzheimer’s pathology,” she added.
“In the longer term, intervention studies will be needed to test whether better prevention and treatment of cardiac dysfunction can help reduce brain microstructural damage and related cognitive decline,” said the researcher.
MNT had the opportunity to speak with Cheng-Han Chen, MD, a board-certified interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, CA, about this study’s findings.
Chen — who was not involved in this study — commented that this research reiterates the importance of maintaining good heart health, not only to prevent heart disease, but also to prevent many conditions in other parts of the body.
“We have long known of a connection between heart health and brain health, but it’s only more recently that we’ve gotten more specific in identifying the specific macro and micro pathophysiological changes that link those conditions,” he explained.
“We will need much more research to understand the mechanisms behind how these specific markers, both lab biomarkers as well as imaging markers, actually are caused by cardiovascular dysfunction,” explained Chen.
MNT also spoke with Sheng Fu, MD, cardiologist with Miami Cardiac & Vascular Institute, part of Baptist Health South Florida, who likewise was not involved in this study.
Fu said hisfirst reaction to these findings is that this reinforces what we experience every day in the management of heart failure, but have limited tools to quantify.
“The brain is an end-organ for the heart, and suffers from poor cardiac output just the same way the liver or kidneys do. The only difference is that it is not so easy to identify how affected the brain is compared to other organs that have more sensitive and specific lab tests. This is an important finding that emphasizes early recognition of systolic dysfunction even in the absence of patient symptoms.”
– Sheng Fu, MD
Fu said he wants readers to understand that the relationship between the brain and the heart is a complex and ancient evolutionary relationship.
“There is a reason the carotid arteries, which feed blood directly to the brain, have such a dense network of receptors to measure blood flow and blood pressure,” he continued. “The brain is constantly measuring how much blood the heart is delivering to it, and sending signals back to the heart in response to alterations of blood flow and blood pressure.”
“While the authors describe imaging modalities that are not yet routine in clinical practice, the message of their study is simple and powerful: taking care of the heart is also taking care of the brain,” Fu added.
