Biological signs of poor heart health linked to later dementia diagnosis – study

Middle-aged adults with biological signs of poor heart health are more likely to go on to be diagnosed with dementia in later life, according to a new study.

These biological signals could be evident up to 25 years before a dementia diagnosis, researchers found.

Experts said people should focus on maintaining good heart health throughout their lives to reduce their risk of dementia later on.

This can be done through being active, managing blood pressure and cholesterol levels and maintaining a healthy weight.

The new study, published in the European Heart Journal, examined levels of a protein called troponin in the blood.

This protein is released into the blood stream when the heart muscle is damaged – for instance, doctors look for very high levels of troponin in people they suspect are having a heart attack.

If there are higher than normal levels of this protein among people without symptoms, this could indicate ongoing and undetected damage to the heart.

Experts from the British Heart Foundation (BHF), which funded the study, said that this could have knock-on effects elsewhere in the body including blood flow to the brain, leading to dementia.

Researchers, led by academics at University College London (UCL), examined long term data from just under 6,000 people who worked for the civil service, who have been tracked for decades.

All of the people had a test to examine troponin levels when they were aged 45 to 69 – none of them had dementia or heart disease when they were given the test.

They were then tracked for an average of 25 years and were given tests at six different time periods to assess their memory and thinking skills.

During the period studied, 695 people were diagnosed with dementia.

Researchers compared each person with dementia to four people without dementia and found that those with dementia had “consistently” higher levels of troponin in their blood.

They said this was apparent in blood tests between seven and 25 years before their dementia diagnosis.

Those with the highest troponin levels at the beginning of the study had a 38% higher chance of developing dementia, compared to those with the lowest levels, they found.

The study authors reported that people with increased levels of troponin had a “faster decline of cognitive function”.

They also examined MRI scans on 641 people involved in the study and found that people with the highest troponin levels at the beginning of the study tended to have a smaller hippocampus – a region of the brain important for memory some 15 years later.

Eric Brunner, emeritus professor of epidemiology and health at UCL, and senior author of the study, said: “Poor heart health in middle age puts people at increased risk of dementia in later life.

“Damage to the brain seen in people with dementia accumulates slowly over the decades before symptoms develop.

“Control of risk factors common to both heart disease, stroke and dementia in middle age, such as high blood pressure, may slow or even stop development of dementia as well as cardiovascular disease.

“We now need to carry out studies to investigate how well troponin levels in the blood can predict future dementia risk. Our early results suggest that troponin could become an important component of a risk score to predict future probability of dementia.”

Professor Bryan Williams, chief scientific and medical officer at the BHF, said: “This study is an important reminder that our heart and brain health are inseparable. The results suggest that middle age is a particularly sensitive time, with damage at this stage setting up a trajectory of decline in heart and brain health.

“Our advice to focus on heart health throughout life also gives our brains the best chance of ageing well. That means keeping our blood pressure under control, managing our cholesterol levels, staying active, maintaining a healthy weight, and not smoking.”

Dr Simon Chen, senior research fellow at UCL, and lead author of the study, added: “Our study represents the longest follow-up to date to investigate links between raised cardiac troponin levels, and cognitive decline and dementia.

“We found that higher blood troponin levels in people with dementia compared with controls were more marked in midlife compared to late life, suggesting that midlife blood troponin levels may be a better biomarker for dementia risk prediction.”