Heart failure, atrial fibrillation, and coronary disease significantly raise dementia risk. Photo / 123RF
Cases of dementia are rising rapidly among the ageing population. Protecting against it begins with looking after your heart.
A landmark new statement released by the American Heart Association warns that three common cardiovascular diseases – heart failure, atrial fibrillation and coronary heart disease – raise the risk of developing dementia, an umbrella term describing a set of symptoms including difficulties with memory, thinking, problem-solving, judgement or language.
Research has shown that 14 to 81% of patients with heart failure experience some degree of cognitive impairment. People with atrial fibrillation have a 39% increased risk of memory or thinking problems, while those with heart disease have a 27% higher risk of developing dementia. Following a heart attack, up to 50% of patients experience cognitive decline.
Vascular dementia, the second most common form of the disease after Alzheimer’s, is predominantly caused by cardiovascular diseases. These compromise the supply of blood to the brain, damaging or killing brain cells by depriving them of the oxygen and nutrients they need to function.
“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 in later life,” said Fernando D Testai, a professor of neurology at the University of Illinois College of Medicine, in the statement.
“The phrase we use is: ‘What’s good for the heart is good for the brain’,” says Dr Ahmad Khundakar, a senior lecturer in biomedical science at Teesside University, whose specialism is dementia and neuroscience.
“Lifestyle factors play a huge part in heart health, which then has a huge impact on brain health, so if we can modify these factors, we can significantly improve our chances of avoiding dementia.”
Understanding these heart conditions is key to understanding what we need to do. Here, we explain what they are, how they’re linked to brain health, and how we can protect ourselves against them.
Heart failure occurs when the heart cannot pump blood around the body as well as it should. It is caused by damage to the heart, commonly due to high blood pressure or heart disease.
“It leads to a constellation of symptoms,” says Dr Sohail Khan, a consultant interventional cardiologist at The Harborne Hospital in Birmingham. “These include fatigue, breathlessness, particularly after activity, and fluid retention, which leads to puffiness. The fluid builds up in the lungs, so patients often wake up in the night gasping for breath.”
Another side effect is a decreased level of oxygen reaching the brain via blood vessels, and it is this which increases the risk of vascular dementia. “Small holes, or hyperintensities, start appearing in the brain’s white matter – essentially, the cabling,” says Dr Khundakar. “They can impact the circuitry involved in cognitive function and memory, damaging them.”
Alzheimer’s is a disease which begins inside the brain, causing plaques to form which lead to neurodegeneration. However, Dr Khundakar says: “It is thought that a lack of oxygen reaching the brain also exacerbates Alzheimer’s pathology, too.”
Tests for heart failure include a blood test and an electrocardiogram (ECG), which records the electrical activity of the heart. It can be treated with drugs such as angiotensin-converting enzyme (ACE) inhibitors, which relax and open up blood vessels, and beta blockers to slow down the heart rate.
Switching to a healthier diet and exercising can lessen the symptoms, but Dr Khan says: “Unfortunately, once you have heart failure it’s very difficult to reverse, so it’s far better to try to avoid it.”
The single most important way to do this is by ensuring blood pressure is at a healthy level. After 40, it’s a good idea to keep an eye on your metabolic health, by getting a health check every five years, including a blood pressure and cholesterol check.
“We should all take responsibility for knowing what our numbers are, as these are our modifiable risk factors, which we can do something about,” says Dr Khan. “Don’t assume your cholesterol will be low, as it may not be.”
A report this year by researchers from UCL found that 7% of dementia cases are attributable to high low-density lipoprotein (LDL) or “bad” cholesterol, in midlife. Reducing saturated fats, maintaining a healthy weight, eating a diet rich in vegetables and good fats, taking regular exercise, avoiding smoking and limiting alcohol are vital for lowering cholesterol and blood pressure.
Atrial fibrillation is a condition which affects 1.4 million people in Britain and causes an irregular and often abnormally fast heart rate. Symptoms include heart palpitations, dizziness and shortness of breath.
It happens when abnormal electrical impulses suddenly start firing in the atria, overriding the heart’s natural pacemaker. Although the cause is not fully understood, “it tends to affect older people, and people with long-term conditions such as heart disease, high blood pressure and obesity”, says Dr Khan.
An irregular heartbeat increases the risk of blood clots forming, which can travel to the brain and cause a stroke. “Major strokes occur when there’s a blockage in a relatively large blood vessel, and that shuts off the oxygen supply to parts of the brain, which affects cognitive function,” says Dr Khundakar.
“There are also transient ischaemic attacks, or mini-strokes, triggered by blockages in very small blood vessels which reach the brain, and these can cause vascular dementia.”
If people are concerned about their heart rate, they can check their pulse themselves: a normal rate should be regular and between 60 and 100 beats a minute when you’re resting.
The condition usually requires medicine, however, so seeking medical attention is crucial. Treatment includes antiarrhythmics such as beta blockers to control the heart rate, and sometimes pacemakers.
Similarly to heart failure, the risk of atrial fibrillation can be reduced by managing weight through diet and exercise, avoiding smoking and drinking to excess, and ensuring blood pressure remains low.
Coronary heart disease can lead to heart attacks and makes people twice as likely to have a stroke.
It occurs when the blood vessels supplying the heart are narrowed or blocked by a build-up of fatty deposits in the arteries. Chest pain and shortness of breath are among the main symptoms of the disease, which is usually diagnosed with a blood test and ECG. It cannot be cured, but can be treated with medication, surgery and angioplasty using balloons and stents to widen arteries.
Research has shown that the combination of heart disease and a genetic predisposition for Alzheimer’s disease trebles the amount of beta-amyloid, a protein that builds up and triggers Alzheimer’s, in the brain.
Scientists at the University of Sheffield also found that heart disease causes a breakdown of a key brain function which links brain activity and blood flow, meaning the brain gets less blood for the same amount of activity. This brain dysfunction is a prelude to dementia.
“Unfortunately, most people have some degree of atheroma, or plaque, by their 20s or 30s, and it gets progressively worse as we age,” says Dr Khan. “But the build-up can be accelerated by high cholesterol and blood pressure, smoking, diabetes, lack of exercise and poor diet.
“So there’s so much we can do to influence our heart health, and in turn, minimise our risk of dementia through our lifestyle choices.”
Telegraph: Is a transactional relationship ever OK? It's complicated, says Rachel Johnson.