Even relatively minor reductions in heart function may be associated with subtle deterioration in brain regions involved in memory, according to a new study examining the growing connection between cardiovascular and cognitive health.
Previous research has linked serious cardiovascular conditions—including heart failure, coronary heart disease and atrial fibrillation—with cognitive impairment and a higher risk of dementia. High blood pressure, elevated cholesterol, obesity and type 2 diabetes are also recognised as potentially modifiable dementia risk factors.
The latest research suggests the heart-brain relationship may begin earlier than previously understood, before a person develops clinically diagnosed heart failure or visible brain shrinkage.
Published in JNeurosci: The Journal of Neuroscience, the study found that small impairments in the heart’s pumping ability were associated with microscopic changes in brain tissue several years later.
Lead author Xia Zhang, a doctoral researcher at Germany’s Max Planck Institute for Human Cognitive and Brain Sciences, said the findings could help scientists understand how cardiovascular dysfunction affects the ageing brain.
Because measurements of heart function are already commonly used in medical care, researchers believe further investigation could eventually help identify people who may benefit from closer cognitive monitoring or earlier preventive treatment.
The study followed 73 participants from the Leipzig Heart Study for approximately three and a half years. Their average age was about 55.
The group included people with diagnosed heart failure as well as participants who had suspected coronary artery disease but had not met the clinical criteria for heart failure.
Researchers wanted to determine whether the relationship between heart and brain health could be detected before severe cardiovascular disease or obvious structural brain damage developed.
The brain depends on the heart to maintain a stable supply of oxygen-rich blood. Researchers said that when the heart pumps less efficiently—even by a relatively small amount—brain tissue may gradually be affected.
The team examined routine indicators of cardiac health, including ejection fraction, which measures the percentage of blood pumped from the heart’s main chamber during each contraction.
They also assessed levels of NT-proBNP, a blood biomarker that can rise when the heart is under increased pressure or strain.
These results were compared with advanced brain scans designed to identify changes in the microstructure of grey matter. Grey matter contains many of the nerve cells involved in memory, decision-making, movement and other essential brain functions.
At the end of the follow-up period, researchers found that lower cardiac pumping efficiency could predict microscopic deterioration in several brain areas associated with memory and known to be vulnerable in Alzheimer’s disease.
The association was observed even among participants who did not have a formal heart failure diagnosis.
Zhang said the findings indicated that brain tissue might be affected by cardiovascular dysfunction earlier than doctors typically recognise.
The affected areas included regions important for memory performance. The microstructural changes also appeared to help explain part of the relationship between poorer heart function and later memory decline.
However, the researchers stressed that the study did not prove participants were developing Alzheimer’s disease.
The investigation did not measure Alzheimer’s-specific biological markers such as amyloid plaques or tau proteins. It therefore could not determine whether the observed brain changes were directly related to Alzheimer’s pathology or represented a separate effect of reduced cardiovascular function.
The findings also do not establish that mild heart dysfunction causes dementia. The study was relatively small and observational, meaning it identified associations rather than proving cause and effect.
Researchers used a brain-imaging measurement known as mean diffusivity to assess the microscopic integrity of grey matter.
This technique may be able to detect tissue-level alterations before conventional scans show visible loss of brain volume. However, it is not currently considered a standard clinical test for cognitive problems in people with cardiovascular disease.
Zhang said the method could eventually provide a sensitive way to recognise early brain changes, but it would require much greater validation before being introduced into routine medical care.
The research team recommended repeating the study in much larger populations with multiple follow-up assessments.
Future investigations should track changes in cardiac function, brain tissue and cognitive performance over longer periods to determine how the relationship develops with age.
Scientists also want future studies to include amyloid and tau testing. This could help establish whether heart-related brain changes occur independently of Alzheimer’s disease, overlap with it or accelerate its progression.
Controlled intervention studies will also be needed to determine whether improving cardiovascular function can prevent microscopic brain damage or slow cognitive decline.
Cardiologists who were not involved in the research said the findings reinforced the broader importance of maintaining good heart health throughout life.
Cheng-Han Chen, an interventional cardiologist at MemorialCare Saddleback Medical Center in California, said researchers have long recognised a connection between the cardiovascular system and the brain.
He said recent advances were helping scientists identify the specific biological and structural changes that may connect heart disease with cognitive decline.
However, Chen emphasised that considerably more research would be required to understand how cardiovascular problems produce the laboratory and imaging markers observed in the study.
Cardiologist Sheng Fu of the Miami Cardiac & Vascular Institute said the brain should be viewed as an organ that depends heavily on the heart’s performance, much like the kidneys and liver.
When cardiac output declines, the brain may receive less blood and oxygen. Unlike problems affecting some other organs, however, early brain injury can be difficult to detect because doctors currently have fewer routine and highly specific tests available.
Fu said the results highlighted the importance of identifying reduced heart-pumping function before symptoms of heart failure appear.
The brain and cardiovascular system continually communicate, with specialised receptors monitoring blood pressure and blood flow to ensure the brain receives an adequate supply.
Although the advanced imaging techniques used in the study are not yet part of standard clinical practice, experts said the central public-health message was straightforward: protecting the heart may also help protect the brain.
Doctors recommend regular health checks, controlling blood pressure and cholesterol, managing diabetes, exercising consistently and following a balanced, heart-healthy diet.
Treating sleep apnoea, avoiding tobacco and limiting alcohol consumption may also support cardiovascular function and healthy brain ageing.
The study adds to evidence that dementia prevention may involve addressing cardiovascular risks long before symptoms of cognitive decline become apparent.
While larger studies are needed, the findings suggest that even small changes in cardiac performance should not necessarily be dismissed, particularly when considering a person’s long-term brain health.
