People with the highest levels of a protein called troponin in their blood were much more likely to develop dementia, the study found.
People with signs of heart damage in middle age are more likely to go on to develop dementia, new research has found.
The key signal was higher levels of cardiac troponin I, a type of protein that is released into the bloodstream when the heart muscle is damaged. Elevated levels can indicate that someone is having a heart attack, which can affect brain health.
But even among people without symptoms of heart problems, higher troponin levels in midlife predicted dementia onset as early as 25 years before diagnosis, according to the study, which was published in the European Heart Journal.
The researchers said the higher troponin levels without symptoms could indicate someone is experiencing ongoing heart damage. This can have ripple effects for people’s health, for example by disrupting blood flow to the brain and raising dementia risks.
“Damage to the brain seen in people with dementia accumulates slowly over the decades before symptoms develop,” Eric Brunner, one of the study’s authors and a professor of social and biological epidemiology at University College London, said in a statement.
“We now need to carry out studies to investigate how well troponin levels in the blood can predict future dementia risk”.
The study included nearly 6,000 people in the United Kingdom who did not have dementia or heart disease. They had high-sensitivity troponin tests when they were aged 45 to 69, and then followed for an average of 25 years.
During that time, 695 people were diagnosed with dementia. Compared with people who did not develop dementia, they had consistently higher levels of troponin in their blood seven to 25 years before diagnosis.
People with the highest troponin levels were 38 per cent more likely to develop dementia than those with the lowest levels, the study found.
They also showed a faster decline in thinking, memory, and problem-solving abilities.
The findings held after the researchers took factors such as sex, ethnicity, and education level into account.
The researchers said elevated troponin levels could one day serve as an early warning sign that someone may be at higher risk of developing dementia.
“Our early results suggest that troponin could become an important component of a risk score to predict future probability of dementia,” Brunner said.