Millions of Brits with heart disease, some of which have gone undiagnosed, may be at increased risk of dementia, a team of experts have warned.
Yet, according to recent research, four in 10 cases of memory-robbing disorder could be prevented with simple lifestyle changes.
Experts say a variety of heart conditions, ranging from an irregular heartbeat to the aftermath of a heart attack, dramatically increase the risk of cognitive decline later in life.
And while almost 8 million Brits are already living with such conditions, around 300,000 are thought to be undiagnosed but still at risk.
According to recent research, four in ten cases of dementia could be prevented with simple lifestyle changes
Three common cardiovascular diseases in adults – heart failure, atrial fibrillation and coronary artery disease – are linked to cognitive impairment and an increased risk of dementia, according to a scientific statement from the American Heart Association (AHA), published in the journal: Myocardial infarctionrevealed.
Cognitive impairment is considered a precursor to dementia, a disorder that robs patients of their memory and independence.
People with atrial fibrillation, a condition that causes an irregular and abnormally fast heartbeat, had the highest risk of developing cognitive problems at 39 percent, followed by people with heart disease who were 27 percent more likely to develop dementia.
In addition, the AHA warned that about half of heart attack and heart failure victims would also develop cognitive decline after the emergency.
There are around 7.6 million people in Britain with cardiovascular disease, and 121.5 million in the US.
More than 1.5 million people in Britain have been diagnosed with atrial fibrillation and is thought to affect up to 6 million Americans each year, while heart failure affects more than a million Britons and almost 6.5 million Americans.
Professor Fernando Testai, an expert in neurology and rehabilitation at the University of Illinois, and chairman of the experts who co-wrote the statement, said cognitive decline in humans had a dramatic impact on both an individual and societal level.
“Managing heart health from an early age is important to prevent cardiovascular disease and cardiac events, protect brain health and reduce the risk of cognitive decline later in life,” he said.
Atrial fibrillation, also known as a ‘silent killer’, was previously thought to affect around a quarter of adults. But Danish scientists found that of those with heart disease, two in five people are likely to develop heart failure during their lifetime
A A meta-analysis of previous studies found that nearly 50 percent of people with heart failure experience some form of cognitive impairment that can affect language, memory or executive functions.
There are several links between heart failure and brain injury; Decreased blood flow can cause mini-strokes or silent brain injuries, and chronic inflammation can also contribute to brain damage.
Atrial fibrillation (AF), a condition characterized by an irregular and abnormally fast heartbeat, also increases the risk of dementia.
Called a ‘silent killer’, it is caused by random electrical impulses that are erroneously fired from the upper chambers of the heart and undermine the heart’s normal rhythm.
This can lead to symptoms such as palpitations and shortness of breath and in some cases to heart failure.
Both dementia and AF share several risk factors, including high blood pressure, type 2 diabetes, heart failure, smoking, vascular disease and sleep disorders.
Strokes and minor brain hemorrhages are also more common in people with AF and are associated with cognitive decline.
It is thought that reduced cardiac output in AF, as in heart failure, may compromise blood flow to important parts of the brain responsible for cognitive function.
Inflammation is linked to both AF and Alzheimer’s disease, and inflammatory biomarkers are linked to an increased risk of blood clots and brain injury, experts say.
More than 1.5 million people in Britain have been diagnosed with AF, around one in 50 people.
But an estimated further 270,000 people are suspected of having AF but remain undiagnosed and unaware of the danger, according to the British Heart Foundation.
Doctors remain baffled about the exact cause of atrial fibrillation, which can lead to strokes.
However, it is known to be more common in people with high blood pressure – a consequence of obesity.
The AHA authors emphasize that effective treatment of AF can reduce cognitive decline.
Coronary heart disease also significantly increases the risk of dementia and cognitive impairment.
Data from multiple large-scale studies show that heart attack is associated with greater declines in memory and executive function.
Increased levels of calcium buildup in the arteries are also linked to a greater risk of developing dementia.
High blood pressure and type 2 diabetes, both risk factors for heart disease, cause inflammation that compromises the blood-brain barrier and reduces blood flow to the brain, leading to cognitive decline and dementia.
Heart disease is also linked to reduced blood flow in the brain, resulting in cognitive impairment.
The same problems with reduced blood flow in the brain are also seen in patients with Alzheimer’s disease, indicating a close link between blood vessel damage and brain degeneration.
The AHA authors added that genetic factors that increase the risk of cardiovascular disease may also contribute to brain shrinkage and cognitive decline.
Medications such as blood pressure treatment can help reduce mild cognitive impairment, but the study authors say it has not been shown to help prevent dementia.
Other studies on heart health and cognitive decline also suggest that heart health can be managed with lifestyle interventions such as diet and exercise, which can also prevent cognitive decline.
Professor Testai said: ‘Although new medicines are being developed with the potential to treat Alzheimer’s disease, the medical community is well aware that prevention is better than cure.
‘More research is needed to confirm and outline how cardiovascular care can improve brain health. In addition, more research is needed to understand the ways in which gender, race and ethnicity can influence the connection between the brain and the heart.”