Hidden heart damage in midlife linked to dementia decades later

When we think about dementia, we usually picture problems that start in the brain. But scientists are finding more and more clues that the heart might be involved too – especially if it’s already under stress in middle age.

A new study shows that damage to the heart, even if it’s quiet and symptom-free, could be a red flag for dementia decades down the line.

The researchers tracked nearly 6,000 people over 25 years, and what they found connects dots between the heart, the blood, and the brain in ways we can’t afford to ignore.

One protein says a lot

The study was led by researchers at University College London (UCL). The team focused on cardiac troponin I, a protein that doctors check when they think someone might be having a heart attack.

But in this study, people didn’t have any major heart symptoms. Their troponin levels were just slightly higher than normal – still, it mattered.

The researchers found that people with the highest troponin levels between ages 45 and 69 were 38% more likely to develop dementia by the end of the study.

This connection held strong even after adjusting for factors like sex, ethnicity, and education.

Dementia doesn’t happen overnight

Dementia creeps in over decades. According to the scientists, signs of damage were showing up in blood tests as early as 25 years before someone was diagnosed with dementia.

That’s a long warning period, and one that could make a real difference if doctors knew how to use it.

Professor Eric Brunner, a senior author on the study, noted that 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,” said Professor Brunner.

“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.”

These early changes don’t just show up on paper – they show up in the brain itself.

Scans reveal brain volume differences

To get a closer look, the team studied brain scans from a smaller group of 641 participants.

The experts found that people who had higher troponin levels in midlife tended to have a smaller hippocampus – the brain’s memory center – 15 years later. They also had less grey matter, the part of the brain that helps us think clearly and solve problems.

The brain volume differences looked similar to what you’d expect in someone three years older. In other words, people with higher troponin levels seemed to have brains that were aging faster.

Signs of cognitive decline

Over time, participants were given tests to measure memory, reasoning, and other mental skills. People with higher troponin levels saw a faster decline in these areas.

By age 80, their mental sharpness looked like that of someone nearly a year and a half older. By 90, it was closer to someone two years older.

That’s not a small change. Over a population, that kind of decline could impact independence, memory, and quality of life.

The heart-brain connection is real

“Our study represents the longest follow-up to date to investigate links between raised cardiac troponin levels, and cognitive decline and dementia,” said Dr. Simon Chen, who led the study.

“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.”

So, this isn’t just about one number in your blood. It’s about how your heart and brain work together – or don’t – over time.

Heart health and dementia

Professor Bryan Williams, Chief Scientific and Medical Officer at the British Heart Foundation, noted that 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,” said Professor Williams.

“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.”

Stopping dementia before it starts

Dementia affects millions of people and their families every year. While there’s no cure yet, this research gives us something important: time.

By paying attention to signs in midlife – especially those hidden signs in the heart – we may have a shot at delaying or even preventing some cases of dementia.

The 2024 Lancet Commission on dementia estimated that 17% of dementia cases could be prevented or delayed just by improving heart-related risk factors like high blood pressure, cholesterol, obesity, and inactivity. That’s almost one in five cases.

That’s why organizations like the British Heart Foundation are now investing heavily – over $10 million into vascular dementia research – to get ahead of the problem.

Middle age might seem early to think about dementia, but the science says that’s exactly when we should start.

The full study was published in the journal European Heart Journal.

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