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 Previous research has linked so-called vascular risk factors,
including obesity, diabetes, smoking, high cholesterol and elevated
blood pressure, to higher odds of dementia, cognitive decline and
Alzheimer’s disease.
But it’s been unclear whether these factors contribute indirectly by
restricting blood flow in the brain, or if they directly cause a
buildup of amyloid protein fragments that are linked to Alzheimer’s.
“In our study, we found an association between the number of risk
factors that people without dementia had when they were middle-aged
and the risk of having amyloid in their brain when they were older,”
said lead study author Dr. Rebecca Gottesman of Johns Hopkins
University School of Medicine in Baltimore.
“Each alone may not be enough to increase the risk of Alzheimer’s
disease, but having a number of these risk factors appears to be
associated with an even higher risk,” Gottesman said by email.
“Although this doesn’t prove causation, it suggests that vascular
risk factors might directly impact Alzheimer’s changes in the
brain.”
Alzheimer’s disease is the most common cause of dementia among older
adults. The progressive brain disorder slowly erodes memory and
thinking skills and eventually leaves people unable to handle basic
tasks in daily life. Scientists suspect that changes in the brain
begin at least a decade before symptoms appear.
For the current study, researchers examined data from 346 adults who
had been evaluated for vascular risk factors since the late 1980s,
when they were 52 years old on average and none of them had
dementia. More than two decades later, when participants were around
76 years old, they had brain scans that looked for evidence of
Alzheimer’s.
At the start of the study, one in five participants had no vascular
risk factors, while 38 percent had one and 42 percent had at least
two.
A higher number of vascular risk factors in midlife, but not in late
life, was associated with elevated brain amyloid, researchers report
in JAMA.
Brain scans found that 31 percent of people with no vascular risk
factors at the start of the study had elevated amyloid later in
life, compared with 61 percent of the people who had at least two
vascular risk factors in middle age.
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Relationships between vascular risk factors and brain amyloid didn’t
differ by race. There also wasn’t a meaningful difference based on
whether people were carriers of what’s known as the ApoE4 allele, a
version of a gene that’s associated with increased risk for
Alzheimer’s disease.
“Brain amyloid is a risk factor that likely begins prior to the
development of memory problems and thus, these findings are very
intriguing,” Dr. Jeffrey Burns, co-director of the University of
Kansas Alzheimer’s Disease Center in Kansas City, said by email. “We
do need to be careful to recognize that amyloid in the brain does
not equal Alzheimer’s disease.”
It’s possible that brain vascular disease might either lead to an
increase in amyloid deposits or a decreased ability to remove
amyloid that accumulates. But the study wasn’t designed to answer
this question, Dr. Andrew Budson, a neurology researcher at The VA
Boston Healthcare System and Boston University School of Medicine
who wasn’t involved in the study, said by email.
Still, the results add to the evidence suggesting that people who
focus on heart health earlier in life may also be safeguarding their
brains, said Dr. Hannah Gardener, a neurology researcher at the
University of Miami who wasn’t involved in the study.
“Patients and physicians need to work together to monitor and
minimize the burden of vascular health factors like smoking,
obesity, blood pressure, cholesterol and diabetes with the goal of
protecting both heart and brain health decades before Alzheimer’s
disease typically manifests,” Gardener said by email.
SOURCE: http://bit.ly/2eRKuCu JAMA, online April 11, 2017.
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