Researchers have uncovered a genetic link between heart disease and Alzheimer’s.
- There is a known association between
Alzheimer’s disease and cardiovascular disease.
- Past research shows there may be a possible
genetic link between these two conditions.
- Researchers from Edith Cowan University in
Australia have found a potential genetic connection between Alzheimer’s
disease and several coronary artery disease-related disorders and lipids
such as cholesterol.
For some time now,
researchers have known there is a
Previous studies have linked heart conditions like
Past research has also discussed a possible genetic
link between Alzheimer’s disease and heart disease. For example, a study
published in November 2018 found that both conditions shared common genetics in
some people.
“Observational studies share strong genetic evidence
supporting a link between coronary artery disease and the risk of dementia, as
well as an increased risk of late-onset Alzheimer’s disease with a genetically
determined risk of coronary artery disease,” Artika Kirby, a PhD
candidate at the Centre for Precision Health at Edith Cowan University in
Australia told Medical
News Today.
“There is also strong evidence of shared genes,
particularly the
“Alzheimer’s disease and coronary artery disease — or
cardiovascular diseases more widely — also share other genes including
Kirby is the lead author of a new study recently
published in the International Journal of Molecular Science that
has found a potential genetic link between Alzheimer’s disease and several
coronary artery disease-related disorders and lipids, such as cholesterol.
What are the
traits of coronary artery disease?
For this study, Kirby
and her colleagues focused on seven traits of coronary artery disease, which
occurs when plaque build-up inside the arteries supplying blood to the heart:
- Angina Pectoris
- Cardiac Dysrhythmias
Coronary Arteriosclerosis Ischemic Heart Disease - Myocardial
Infarction (Heart Attack)
- Nonspecific
Chest Pain
- Coronary
Artery Disease.
Scientists also focused on 13 different lipids
associated with coronary artery disease, including lipoproteins, triglycerides, and cholesterol.
“During our literature search, we evidenced a lack of
evidence for Alzheimer’s disease and coronary artery disease traits,” Kirby
explained.
“Given the significant risk of Alzheimer’s disease and
cardiovascular diseases — including coronary artery disease traits — globally,
we were motivated to investigate potential genetic links between Alzheimer’s
disease and coronary artery disease traits,” she added.
Genetic link
between Alzheimer’s and coronary artery disease
The researchers used a
three-way cross-traits genetic analysis for their study.
At the study’s conclusion, they found a notable
genetic connection between all of the seven coronary artery disease traits assessed,
as well as triglycerides.
“A positive global genetic correlation refers to, at
the very least, the potential for some individuals with a genetic
predisposition to elevated levels of triglycerides or any of the seven coronary
artery disease traits assessed in our study to a potentially increased risk of
Alzheimer’s disease,” KIrby said.
Additionally,
the scientists discovered a genetic overlap between Alzheimer’s disease and
three more lipid measurements — high-density lipoproteins (HDLs), low-density
lipoproteins (LDLs), and total
cholesterol — and also identified genome-wide significant genes shared across
Alzheimer’s disease, several lipids, and coronary artery disease traits.
“Investigating gene overlap, especially whether there
is gene overlap more than by chance, sheds light on the possibility of shared
(overlapping) genes across multiple diseases such as Alzheimer’s disease, several
lipids, and coronary artery disease traits,” Kirby said.
According to the researcher, “[t]hese findings can
improve our understanding of the underlying biological mechanisms, and
interconnectedness at the gene level, between Alzheimer’s disease, select
lipids, and coronary artery disease traits.”
“Further genetic studies can help us better understand
the genetic underpinnings of Alzheimer’s disease and coronary artery disease—
and cardiovascular diseases more widely — in how the diseases may interact at
the gene level,” she added. “This can allow us to better understand the onset
and progression of Alzheimer’s disease, and potentially work towards finding
therapeutic targets for both Alzheimer’s disease and cardiovascular diseases.”
Is there a
causal relationship between heart disease and Alzheimer’s?
After reviewing this
study, Cheng-Han Chen, MD, a
board certified interventional cardiologist and medical director of the Structural
Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, CA,
told MNT he
found it interesting.
“Some
studies have shown a connection between Alzheimer’s and some other
cardiovascular disease risk factors, such as hyperlipidemia, but
this study is interesting in that it digs down to the underlying genetics for
each of these separate conditions,” Chen said.
Nevertheless, he cautioned that: “It definitely is a
large leap, I should say, to make this connection, as the genes that they
identified are not really understood in their functions and their actual
connections to each of those conditions were either Alzheimer’s or
cardiovascular disease.“
“So it’s a long way to go to say that they’re actually
causative or dependency related to each of the conditions. This is more of an
association study, just to say that there may be some sort of genetic
association that is common to both conditions,” he added.
MNT also
spoke with Heather M. Snyder, PhD,
senior vice president of medical and scientific operations of the Alzheimer’s
Association, about this study.
Snyder, who was not involved in the research,
commented that:
“This is an interesting
paper taking a unique lens to understanding the connection between the brain
and the heart — specifically the genetics that may link coronary artery disease
and Alzheimer’s disease. The study found a number of shared genes of interest,
but did not find a shared causal link between the two diseases through the
genes.”
“For researchers, discovery of these shared genes may
provide clues into areas of biology that these diseases ‘share,’ which may —
with further investigation — provide insights into possible treatment methods
or targets, including repurposed drugs,” she added.
Better
understanding of the heart-brain link needed
Readers may wonder how a
neurological condition and a heart condition could possibly share genetics.
“Assuming that there is a relationship, it currently is not very well
understood,” Chen told MNT.
“It could either be that
there are shared genetic risk factors for each of the conditions, such that if
you have those genes, you’re more prone to have some traits that will
predispose you to both heart disease and Alzheimer’s. The other possibility is
there really is a genetic connection that we do not even understand at all. So
the short answer is ‘we don’t know’.”– Cheng-Han Chen, MD
“This is just the
beginning,” he continued. “There will be a lot of future research that will
need to build upon these identified genes to see, number one, what they do,
number two, how exactly they’re related and what potential mechanisms could be
involved between those gene products and eventual risk for developing either
Alzheimer’s or cardiovascular disease. And so there’s a lot of research in
between that needs to be done.”
Snyder commented that there are numerous lines of
research that make the connection between our heart health and brain health.
“For instance, individuals with cardiovascular disease
are at an increased risk for Alzheimer’s and other diseases that cause
cognitive decline,” she explained.
“A large study known as
“For clinicians, this study reinforces the importance
of regularly including discussion about brain health, as we do about heart
health, in their interactions with patients,” said Snyder. “A next step for
this work is to further advance an understanding of the linking biological
underpinnings with further investigation of the common mechanisms and pathways
that may link coronary artery disease, lipids, and Alzheimer’s.”
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