New research from University College London has found that people who show early signs of heart damage in middle age are more likely to develop dementia later in life.
The study, published in the European Heart Journal, followed thousands of people for up to 25 years and discovered that higher levels of a heart protein in the blood could be an early warning sign of future brain decline.
The protein, called cardiac troponin I, is released into the blood when heart muscles are damaged. Doctors usually check troponin levels when someone is having a heart attack, because the levels rise sharply.
But this study looked at smaller, long-term increases in troponin that don’t cause any symptoms. These small increases can indicate ongoing “silent” heart damage that might slowly affect the brain over time.
The researchers studied nearly 6,000 participants from the Whitehall II study, which began in 1985 and has followed British civil servants for decades to learn more about aging and health.
All participants were between 45 and 69 years old when they had their first blood test for troponin. At that time, none of them had dementia or heart disease. The team then tracked their health for an average of 25 years, regularly checking memory and thinking skills.
During that time, 695 people developed dementia. When the researchers compared people with and without dementia, they found that those who later developed dementia had higher levels of troponin in their blood many years earlier—sometimes up to 25 years before their diagnosis.
People with the highest troponin levels at the start had a 38% higher risk of developing dementia by the end of the study compared to those with the lowest levels.
Even after accounting for age, sex, ethnicity, and education, people with higher troponin levels showed faster decline in memory, reasoning, and problem-solving. By age 80, their brain performance was similar to that of people almost a year and a half older, and by age 90, it was equal to someone two years older.
In another part of the study, 641 participants had brain scans about 15 years after their blood tests. Those with higher troponin levels tended to have a smaller hippocampus—the area of the brain that helps with memory—and less gray matter, which plays a key role in processing information.
These differences made their brains look about three years older than those of people with lower troponin levels.
Researchers believe this happens because heart damage affects blood vessels and circulation, which can reduce oxygen and nutrients reaching the brain. Over many years, this can cause the slow buildup of damage that leads to dementia.
Professor Eric Brunner, a senior author of the study, said that heart and brain health are closely linked. He explained that damage to the brain begins decades before dementia symptoms appear and that managing heart health in midlife could delay or even prevent the disease.
Dementia is a general term for several brain disorders that cause memory loss and difficulties with thinking and behavior.
The 2024 Lancet Commission on dementia found that nearly one in five cases could be prevented or delayed by improving heart and blood vessel health. High blood pressure, high cholesterol, lack of exercise, and obesity are some of the biggest risk factors.
Lead researcher Dr. Simon Chen said this was the longest study so far to look at how troponin relates to dementia. He added that troponin might one day be used as a simple blood test to predict dementia risk many years before symptoms appear.
Experts not involved in the research agree that the study highlights how important it is to take care of the heart from an early age. Professor Bryan Williams from the British Heart Foundation said that damage in middle age may set the stage for both heart and brain decline later on.
He emphasized that controlling blood pressure, managing cholesterol, staying active, maintaining a healthy weight, and avoiding smoking are key to protecting both heart and brain health.
In summary, this long-term study suggests that even small, silent heart damage in middle age can have lasting effects on the brain. Troponin could become an important clue in predicting dementia risk before symptoms start. The findings show that protecting the heart early in life may also protect the mind in the decades to come.
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The study is published in the European Heart Journal.
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