Heart attacks linked to faster cognitive decline in new study

• In the United States, someone has a heart attack every 40 seconds.
• Survival rates have improved greatly over the past few years; now almost 90% of people who experience a heart attack will survive it.
• Heart health is strongly related to brain health, as healthy blood flow is vital to the functioning of the brain.
• A large-scale study has now found that older adults who experience a heart attack show a faster rate of cognitive decline in the following years than those who do not.

According to the Centers for Disease Control and Prevention (CDC), heart disease is the leading cause of death in the United States, causing one death every 33 seconds. And every year, about 805,000 people in the U.S. have a heart attack or myocardial infarction (MI).

A heart attack occurs when the blood supply to the heart muscle is interrupted, usually by a blockage in an artery. This deprives the muscle of oxygen and nutrients, and may lead to a cardiac arrest, where the heart stops beating.

The vast majority of people who experience a heart attack will survive — only around 12% of heart attacks are fatal. To reduce the chances of experiencing a further heart attack, the CDC advises people to follow a healthy diet, increase their physical activity, stop smoking and try to reduce stress, as well as take their prescribed medications.

Some studies have suggested that a heart attack may increase the chance of developing dementia, but the evidence has, so far, been inconclusive.

Now, a large-scale study has found that people who have had a heart attack have a faster rate of cognitive decline than those who have not.

The study is published in JAMA Neurology.

“This newly-published research investigates a very large and relatively diverse population ([more than] 30,000 people) from six well-characterized, long-term U.S. studies. The aim was to confirm and more specifically describe the impact of heart attack on cognitive functioning, and to specifically examine the impact of race and sex.”

– Dr. Percy Griffin, Alzheimer’s Association director of scientific engagement, not involved in the study

No previous cognitive issues

In total, 30,465 people (mean age 64 years) were included in the study. At the start of the study, all participants were screened for a history of MI, dementia, or stroke, and anyone with a history of any of the conditions was excluded from the study.

Of the participants, 56% were female. The majority were white (69%), 29% were Black, and 8% Hispanic.

During follow-ups of between 4.9 and 19.7 years (median 6.4 years), 1,033 participants had at least one heart attack. The remaining 29,432 did not have any MI events.

The researchers carried out one or more cognitive assessments with all participants at the start of the study, with additional assessments following heart attacks.

To determine cognitive function, the researchers assessed:

• global cognition — executive function or processing speed, learning or memory, general mental status, and language, motor, and visuospatial ability
• memory — learning or delayed recall
• executive function — complex or speeded cognitive function.

Faster cognitive decline after heart attack

All participants, as expected, showed some age-related cognitive decline during follow-up. However, the researchers found that decline was faster in all three measures — global cognition, memory, and executive function — in those who had experienced a heart attack than in those who had not.

Dr. Griffin, not involved in the study, explained: “The researchers found that, in the overall group, post-heart attack general cognition, memory and decision-making did not significantly decline right away, but declined over time at a significantly faster rate.”

“The eventual decline in global cognition for those in the study who experienced a heart attack was equivalent to 6 to 13 years of cognitive aging,” he told us.

For those who experienced a second heart attack, the overall rate of decline did not change, but they did show an acute decrease in executive function immediately following the second heart attack.

The researchers also found differences in the effect of heart attacks by race and sex. Black people were more likely to show an acute change in global cognition following a heart attack, but this decline then slowed and overall was lower than in white people.

Women showed a slower rate of decline in cognitive function, but a faster decline in executive function than men.

Why might heart attacks accelerate cognitive decline?

A previous study in a large cohort of heart attack survivors found that heart attack was associated with a higher risk of vascular dementia, particularly in patients with stroke during follow-up.

This latest study found an increased rate of annual cognitive decline following a heart attack that was independent of stroke and atrial fibrillation (AFib).

The researchers suggest that this acceleration in long-term cognitive decline might be a result of “long-standing cerebrovascular disease, such as white matter disease from hypertension. It may initiate a process of vascular dementia through systemic inflammation leading to oxidative stress, chronic hypoperfusion secondary to impaired left ventricular ejection fraction, development of [AFib], or subclinical ischemic stroke.”

And Dr. Griffin added that: “The risk of developing Alzheimer’s disease or vascular dementia appears to be increased by many conditions that damage the heart and blood vessels. These include heart disease, diabetes, stroke, high blood pressure and high cholesterol.”

“The results emphasize the need for more research and real-world action to reduce health and health care inequities, and improve detection and treatment of vascular risk factors,” he continued.

Healthy heart, healthy mind

This study provides more evidence of the link between cardiovascular health and brain health. Reducing your risk of heart disease by maintaining a healthy diet and lifestyle could also be key to reducing your rate of long-term cognitive decline and risk of dementia.

Dr. David Merrill, a psychiatrist and the director of the Pacific Neuroscience Institute’s Pacific Brain Health Center in Santa Monica, CA, not involved in the research, told Medical News Today:

“With a heart attack, there may be compromise of cardiac function that lasts beyond the acute event. While the brain may compensate at the time of the MI, we see that the trajectory of dementia risk is changed over time. This implies that the major health stress to the body from an MI extends to impact the Iong term health of the brain.”

“These findings stress both the need to prevent heart attacks but also the critical need for both cardiac and brain rehabilitation following major health events like heart attacks,” he added.

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