Heart damage in middle age linked to increased risk of dementia in older adults

A study of 6,000 people, published in the European Heart Journal, found that middle-aged people with elevated levels of a protein called cardiac troponin I in their blood have a higher risk of developing dementia in old age. Scientists found higher troponin levels in people with dementia compared to those without it as early as 25 years before diagnosis.

Troponin is released into the bloodstream when the heart muscle is damaged. Doctors look for very high troponin levels in people suspected ofhaving a heart attack . However, elevated troponin levels without symptoms may indicate hidden, ongoing damage to the heart muscle or problems with its function. This can have side effects in other parts of the body, affecting the health of blood vessels and the blood supply to the brain, which can lead to dementia.

All participants underwent a highly sensitive troponin test between the ages of 45 and 69, which measures troponin levels in the blood at levels significantly lower than those seen after a heart attack. None of these individuals had dementia or cardiovascular disease at the time of their initial troponin test. They were then followed for an average of 25 years, undergoing six-point tests to assess their memory and cognitive abilities.

During the study, 695 people were diagnosed with dementia. By comparing each person diagnosed with dementia with four people without the diagnosis, the researchers found that people with dementia had consistently higher blood troponin levels. This was confirmed by blood tests performed 7–25 years before diagnosis. People with the highest troponin levels at the beginning of the study had a 38% higher risk of developing dementia by the end of the study than those with the lowest levels.

Scientists have calculated that 17% of dementia cases could be prevented or delayed by improving cardiovascular risk factors, including high blood pressure and cholesterol, physical inactivity and obesity.