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Heart attacks could accelerate onset of dementia

In the past, heart attacks and brain decline have been addressed as two separate medical issues. More recently, however, scientists have begun to understand that there is a close relationship between the two organs, and a recent research study even links the occurrence of a heart attack with more rapid subsequent cognitive decline in survivors. 

“For too long, we have thought about and addressed heart disease and brain disease as two separate conditions,” explained Dr. Michelle Johansen from the Johns Hopkins University School of Medicine. “Based on our study’s findings and other research, I don’t think we’re going to be able to keep doing that as we learn more,” she said.

The research, conducted in conjunction with the American Heart Association, analyzes data from six long-term studies on cardiovascular health that were carried out between 1971 and 2017. These previously published investigations involved a total of 31,377 people, with a median age of 60, who had no evidence of heart disease or dementia when the research studies commenced. The participants were monitored for between five and 20 years (median of 6 years), and during this time 1,047 of them suffered a heart attack.

The researchers explain that, in order to use the published data to track what happens to cognitive function in the years following a heart attack, they first had to “harmonize” the data. Because the studies had tested participants at different time intervals and using different tests of cognitive function, a team of neuroscientists and statisticians had to work out ways of ensuring the data collected in all the studies were comparable. 

For the pooled data, cognitive performance was assessed in three ways – in terms of memory, executive functioning and global cognition. Executive function refers to a person’s ability to pay attention, plan, organize, and make complex decisions, while global cognition was assessed using tests of memory and executive function combined. The researchers were interested in whether any of these measures of cognitive performance declined immediately after, or in the years following the occurrence of a heart attack.

The results of the analysis showed that, while cognitive function did not change significantly immediately after a heart attack, it did in subsequent years. Heart attack survivors suffered a more rapid decline in memory skills, executive function and global cognition than people who had not had a heart attack. The most significant differences were found several years after the heart attack had taken place. 

“We have shown that having a heart attack can be detrimental to your brain health over time,” said Dr. Johansen. “Dementia is a slow, step-wise process. One doesn’t wake up out of the blue with dementia.”

The reasons that dementia is accelerated in heart attack survivors are not yet clear. Both organs are metabolically active and rely on a steady supply of oxygen to the tissues. It is possible that shared risk factors, such as poor diet, smoking and high blood pressure, are present for both conditions and would therefore have impacts on the functioning of both organs. Alternatively, the researchers suggest that ongoing damage to the brain from silent strokes, which are not large enough to cause noticeable symptoms but still reduce the supply of blood to the brain, could accelerate mental decline.

The findings, which will be presented at the American Stroke Association’s International Stroke Conference, (Feb 8–11, 2022), have important implications for the way in which physicians manage heart attack survivors. They also indicate that lifestyle choices that support good heart health will be just as important when it comes to limiting mental decline.

“It’s important to know that cognitive decline is a possibility after a heart attack, so physicians are both managing patients’ heart disease and looking for signs of dementia following a heart attack,” said Dr. Johansen. “It can even be a great conversation starter about why it’s important for patients to follow medical advice to prevent a heart attack.”

“We need to realize that what’s going on in the heart and brain are related. Managing risk factors to prevent a heart attack is actually good for your brain as well.”

The research will be presented at the American Stroke Association’s International Stroke Conference 2022.

By Alison Bosman, Staff Writer

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