Poorer heart health in middle age linked to increased dementia risk: Study

People with signs of damage to their heart during middle age are more likely to develop dementia in later life, according to a new study led by UCL (University College London) researchers.

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 I in their blood were more likely to go on to develop dementia in later life. The team found higher troponin levels in those with dementia, compared to those without, as far back as 25 years before their diagnosis.

Troponin is released into the bloodstream when heart muscle is damaged. Doctors look for very high levels in people they suspect of having a heart attack. However, higher-than-normal levels of troponin, without symptoms, could indicate silent, ongoing damage to the heart muscle or problems with its function. This can have a knock-on effect elsewhere in the body, impacting blood vessel health and blood flow to the brain, and leading to dementia.

Senior author Professor Eric Brunner (UCL Institute of Epidemiology and Health Care) 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.”

Dementia is an umbrella term for a range of conditions that involve damage to brain cells, leading to a decline in memory, thinking, and reasoning abilities. The 2024 Lancet Commission on dementia, led by Professor Gill Livingston (UCL Psychiatry) who also co-authored this latest paper, estimated that 17% of cases of dementia could be prevented or delayed by improving cardiovascular risk factors, including high blood pressure and cholesterol, physical inactivity, and obesity.*

This new study involved nearly 6,000 participants in the Whitehall II study, which has followed people who worked for the British Civil Service since 1985 for decades to understand more about health and ageing**; Whitehall II is led by Professor Mika Kivimaki (UCL Psychiatry), who also co-authored this latest paper. All participants had a high-sensitivity troponin test when they were aged between 45 and 69, which can measure troponin in the blood at levels much lower than after a heart attack.

None of these people had dementia or cardiovascular disease when they were given their first troponin blood test. They were then tracked for an average of 25 years, completing tests at up to six points to assess their memory and thinking abilities.

During the study, 695 people were diagnosed with dementia. When researchers compared each person with a dementia diagnosis to four people without, they found those with dementia had consistently higher levels of troponin in their blood. This was apparent in blood tests they had between seven and 25 years before their diagnosis.

People with the highest troponin levels at the beginning of the study had a 38% higher chance of developing dementia by the end of it, compared to those with the lowest levels.

After taking into account factors including sex, ethnicity and education level, researchers found that people with higher troponin levels between the ages of 45 and 69 showed a faster decline in their thinking, memory and problem-solving abilities.

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.

Researchers then investigated a group of 641 people from the study who also had an MRI scan of their brains. Compared to those with the lowest levels, 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 – 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.

These findings from the brain scans suggested the participants’ brains were equivalent to those of people around three years older, according to the researchers.

Lead author Dr Simon Chen (UCL Psychiatry) said: “Our study represents the longest follow-up to date to investigate links between raised cardiac troponin levels, and cognitive decline and dementia.

“We also 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.”

Professor Bryan Williams, Chief Scientific and Medical Officer at the British Heart Foundation, commented: “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.

Reference: Poorer heart health in middle age linked to increased dementia risk, University College London, Journal: European Heart Journal, DOI 10.1093/eurheartj/ehaf834