Even mild heart problems may cause microscopic damage in brain regions crucial for memory, potentially increasing the risk of cognitive decline, according to a new study.
Researchers found that reduced efficiency in the heart's pumping function, even in individuals without full-blown heart failure, can lead to subtle yet detectable damage in the brain's gray matter. This damage can accumulate over years, creating a potential pathway to memory loss and other cognitive issues.
The study, published in the Journal of Neuroscience, involved 168 participants, including 73 with coronary artery disease or heart failure and 95 healthy controls. Over 3.5 years, scientists measured participants' cardiac function, including left ventricular ejection fraction (LVEF), a measure of how well the heart pumps blood, and levels of NT-proBNP, a hormone released by the heart under stress. Advanced MRI scans were used to detect microscopic gray matter damage, and heart patients also underwent cognitive tests.
The findings indicated that weaker heart pumping at the beginning of the study predicted greater microscopic brain damage later on, even in participants without heart failure. Among heart patients, this brain damage was directly correlated with poorer memory performance, particularly in brain regions vulnerable to Alzheimer's disease.
"The broader implication is that the brain may show subtle tissue-level changes related to cardiac dysfunction before we see obvious brain shrinkage or clinical dementia," said study co-author Dr. Xia Zhang, a doctoral researcher at the Max Planck Institute for Human Cognitive and Brain Sciences in Germany.
When the heart pumps less efficiently, the brain receives less blood, oxygen, and nutrients. The brain utilizes about 20 percent of the body's oxygen despite being only two percent of its weight. This reduced supply can damage tiny blood vessels, weaken the brain's protective barrier, and trigger inflammation in memory-related areas, such as the cingulate and lingual gyri. The heart also releases stress hormones and proteins that can further fuel inflammation within the brain.
While the study does not confirm these changes directly cause Alzheimer's disease, it provides strong evidence that cardiac dysfunction leaves early, measurable marks on the brain. This suggests a potential window for interventions before significant cognitive impairment occurs.
Cardiovascular disease is a growing global concern. In the U.S., heart disease remains the leading cause of death. Approximately 44 percent of older adults with heart failure exhibit signs of cognitive decline, with some estimates suggesting the figure could reach 80 percent. As the prevalence of heart conditions rises, the population at risk for this type of subtle brain damage also increases, highlighting the heart-brain connection as a critical public health issue.
Dr. Zhang noted that these findings might help explain the link between regular physical activity and improved brain health. Exercise supports cardiovascular function, vascular health, and cerebral blood flow, all of which may help protect brain tissue over time.