Middle-aged adults with signs of poor heart health are more likely to develop dementia later in life, a study has found.
It’s long been known that poor heart health can reduce blood flow in the brain, resulting in memory loss and confusion.
But the warning signs of dementia could be evident up to 25 years before a diagnosis, just by looking at a patient’s heart health, researchers at University College London found.
Researchers also suggested dementia, which affects more than 980,000 people in the UK, can be prevented or delayed by improving cardiovascular risk factors, including high blood pressure and cholesterol.
“Poor heart health in middle age puts people at increased risk of dementia in later life,” said Senior author Professor Eric Brunner at UCL. “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,” he added.
The study, published in the European Heart Journal and funded by the British Heart Foundation, found middle-aged people with higher levels of a protein called cardiac troponin in their blood were more likely to go on to develop dementia in later life.
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. It can have a knock-on effect elsewhere in the body, impacting blood vessel health and blood flow to the brain, and leading to dementia.
For the study researchers examined decades worth of data from just under 6,000 people who worked for the civil service.
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 per cent higher chance of developing dementia and a “faster decline of cognitive function”, compared to those with the lowest levels, they found.
Their mental abilities at the age of 80 were equivalent to those of people almost a year and a half older, based on cognitive tests. At the age of 90, their mental abilities were equivalent to those of people who were two years older.
“Our early results suggest that troponin could become an important component of a risk score to predict future probability of dementia,” Professor Brunner said.
Researchers 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.
They also tended to have a smaller volume of grey matter in their brain – the outer layer of the brain which is important for processing information.
To help reduce the risk of dementia later in life, experts suggest people should focus on maintaining good heart health throughout their lives.
This can be done through being active, managing blood pressure and cholesterol levels and maintaining a healthy weight.
Professor Bryan Williams, Chief Scientific and Medical Officer at the British Heart Foundation, 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.”