Older people who suffer from a type of irregular heartbeat called atrial
fibrillation may also be more likely to experience mental declines sooner, a new
"Problems with memory and thinking are common for people as they get older,"
said lead researcher Evan Thacker, a statistician in the department of
epidemiology at the University of Alabama at Birmingham. "Our study shows that,
on average, these problems may start earlier or get worse more quickly in people
who have atrial fibrillation. This means that heart health is an important
factor related to brain health."
As with other such studies, this one established only an association between
atrial fibrillation and mental decline, not a direct cause-and-effect
Why some people struggle
That's why the next step is to find out why people with atrial fibrillation
start to struggle with memory and thinking sooner, Thacker said.
There are at least two possibilities, he said. First, people with atrial
fibrillation may have small blood clots form in the heart that then become
lodged in the brain.
"These may be too small to cause noticeable strokes, but may over time cause
small damage to the brain that would eventually lead to mental decline," Thacker
Second, people with atrial fibrillation may simply have less blood flowing to
the brain, he said.
"This could result in the brain not getting as much oxygen and nourishment as
it needs, which could lead to damage over time that would result in mental
problems," Thacker said.
"Currently, we do not know whether either of these two possibilities actually
occurs," he said. "We would like to study it using brain imaging technology to
learn more about what is happening in the brains of people with atrial
Eventually, if doctors and researchers can discover why people with atrial
fibrillation show accelerated mental decline, they might be able to learn how to
prevent the problem, Thacker said.
Dr Gregg Fonarow, a professor of cardiology at the University of California,
Los Angeles, said, "Atrial fibrillation is present in close to 3 million men and
women in the United States and increases the risk of stroke fivefold compared to
the general population."
How the study was done
In addition to the marked increase in the risk of stroke, more recent
research suggests that atrial fibrillation is associated with an increased risk
of mental decline and dementia, he said.
"Repetitive, small subclinical strokes in patients with atrial fibrillation
may account for these findings," Fonarow said.
He said giving blood thinners to patients with atrial fibrillation is
standard care to prevent clots in the heart from migrating to the brain.
Putting these patients on anticoagulants, such as warfarin or one of the
newer therapies, will "likely be effective in not only reducing the risk of
stroke, but also reducing the significant risk of mental decline and dementia,"
To see the effect atrial fibrillation had on memory and thinking, Thacker's
team collected data on more than 5 000 people aged 65 and older who took part in
the Cardiovascular Health Study.
At the start of the study, none of the participants had atrial fibrillation.
Over an average of seven years of follow-up, more than 550 people developed the
condition, the researchers noted.
Each year during the study, all the participants were given a 100-point
memory and thinking test.
The researchers found that people with atrial fibrillation were more likely
to have lower scores on the test at an earlier age, compared with those who
didn't develop atrial fibrillation.
For example, the average score on the test decreased by about six points for
people without atrial fibrillation between ages 80 and 85, compared to about 10
points for those with atrial fibrillation.
For those aged 75 and older with atrial fibrillation, the average decline was
about three to four points faster every five years, compared to people without
Scores below 78 points are associated with dementia, Thacker said.
The researchers predicted that on average, those without atrial fibrillation
would score below 78 when they were 87, while people with atrial fibrillation
would score below 78 when they were 85.
For more on atrial fibrillation, visit the American