Welcome to the program. I'm your host
Neal Howard. Thank you for joining us
here. Today, I've got a guest in studio
Dr. Ahmed Tawakol, he's co-Director of
Cardiac MR and PET CT program and he's
joining us today to talk about his work
in the field of cardiology they're at
Mass General, his research and some of
the topics that he presented recently at
the American Heart Association's
Scientific Sessions 2017. Welcome to the
program Dr. Ahmed Tawakol. How are
you? I'm doing well. Thanks for inviting me.
Let's give our listeners a bit of
background about yourself, you are
cardiologist. Describe some of your
training and background in the field and
a little bit about your role there at
Massachusetts General. Sure. I went to
Stanford Medical School after which I
was at the Brigham and Women's Hospital
in Boston for internship residency and
cardiology fellowship. And then I did
advanced imaging training and nuclear
cardiology at the Massachusetts General
Hospital. I've been here since my
training years. Currently, I'm co-Director of
the Cardiac MR PET and CT program, also a
practicing cardiologist. Now recently as
I mentioned that you participated in the
American Heart Association's Scientific
Sessions 2017. What are the scientific
sessions? Do they cover a number of
topics or is it cardiology related? What
is your knowledge with that event
there? The American Heart Association
Scientific Sessions is one of our
largest scientific sessions in the field
of Cardiology, it's an exciting meeting.
People present topics in Cardiology that
are very wide from treatment and
diagnosis of cardiac diseases to really
trying to understand the basic biology
to far-reaching aspects touching on
cardio metabolic disease as well as
socioeconomic factors leading to
cardiovascular diseases. It's very broad
for the clinicians and scientists
attending. It's an opportunity to
really leverage that breadth and kind of
expand on the topics that one would
otherwise typically be exposed to and
kind of cut
try to grow through greater
exposure to exciting new science. Well
let's talk about maybe one of those
scientific breakthroughs or topics that
you personally presented at this year's
session. So one of the aspects that
my group has been particularly
interested in better understanding is
the link between socio-economic stress
and disease. We've known for centuries
literally that there is an increased
incidence of disease in individuals who
have protracted stress. But only recently
have we begun to understand how that
works, for example for a long time, we
were biased to believe that the link
between stress and disease was really
carried by either behaviors or increased
blood pressure. But that it wasn't
necessarily an independent risk. But over
the last decade and a half or so, large
studies with up to 25,000 patients
included for example have shown that the
link between stress and diseases is
really independent. About 5 to 7
years ago, animal studies started to
suggest that the stress brain might
trigger an inflammatory response where
the bone marrow produces a lot of extra
cells that contribute to inflammation. So
we wanted to see if a similar
phenomenon were occurring in humans
where stress leads to activity in
the brain that then generates an
inflammatory response by prompting the
bone marrow to produce more immune cells.
We recently published a paper where we
observed just that and 293 individuals
who had brain imaging and who were then
followed for up to 5 years to look
for the development of cardiovascular
conditions such as myocardial infarction
and stroke. We saw that the
amount of metabolic activity in the
amygdala, the portion of the brain that
is highly responsive to stress was
independently predictive of their risk
of subsequent stroke and heart attacks.
And that it was a relatively strong
signal, the individuals who had
strokes and heart attacks soon after
imaging had the highest amygdala
activity. Those who had latter events had
intermediate activity and those who
never developed an event had the lowest
activity. We also found that the activity
in the brain predicted the activity in
the bone marrow as well as inflammation
the artery wall and were able to
construct a model that was very similar
to what was seen in animals where stress
begets highly active amygdala which
prompt increased bone marrow turnover of
immune cells which prompts more arterial
inflammation which then leads to
cardiovascular disease events.
The interest there is that kind of
system, gives us now an opportunity to
try to interrupt it and once you
characterize a system, there's then that
chance that you can devise treatments to
try to modulate that system in hopes of
reducing stress-related cardiovascular
disease events. Basically, dealing with it
after the stressors have already done
the damage, how much effort goes into
making sure that those stressors don't
reactivate to the bone marrow in the
future while doing whatever treatment
that that you're administered?
That's a really good question.
So what's interesting about the
brain and response to stress is that
imagine stress as a weight and the
amygdala as a muscle, the more exposure
to stress the amygdala has the larger it
becomes the more active it becomes. So
stress begets more stress sensitivity.
And so the issue is not so much to
get rid of the stress I mean that's
a very hard task for physicians to be
able to modulate and actually very hard
to ask for anybody's try to manage.
The more reasonable ask is to try to
change the response to stress and there
are ways to do that, you can
have a reduced sensitivity to stress by
reducing the size and activity of the
amygdala and that could be one of the
ways to modulate the downstream
responses. One could also devise drug
therapies that could interrupt some of
the downstream stages, for example the
production of inflammation is something
that we could target with specific
anti-inflammatory measures. Have you
noticed or touched upon any methods not
drug related that reduce the size of the amygdala?
So we are starting to look at that but
other groups have demonstrated that some
meditative aspects could reduce the size
and activity of the amygdala. And so
that's one interesting approach for
example mindfulness meditation has been
shown to shrink the volume of the
amygdala.
Others have noted that exercise can very
nicely reduce some of those downstream
stress responses and also have other
very fascinating impacts on the brain as
well. So yes, there are
there are some non-pharmacologic aspects
that might indeed be very, very
interesting.
Are those solely based on the progress
of the stress and the size of the amygdala?
The mindfulness meditation and
exercise can affect the size and
activity and the downstream impacts are
things that still require a little
more study. Though I would add that there
was a very interesting study published
about a year ago where they took
individuals with recent heart attacks or
or heart procedures and randomized them
to either standard cardiac rehab with
exercise or rehab with exercise and the
addition of a stress reduction. And what
what they found is the individuals who
had the more complete cardiac rehab with
stress reduction experienced a 50%
relative risk reduction and subsequent
heart attacks and strokes or
cardiovascular disease events over the
next 5 years. That's a relatively
small study and certainly requires
replication in a much larger cohort but
kind of gives us some insight into the
possibility that a stress reduction
approach might have benefits in terms of
cardiovascular diseases. Of course, the
mechanism of that benefit is something
that also requires some study. Now this
is a question that I should have
asked at the outset but in wrapping up, I
want to go ahead and touch on it. When it
comes to imaging to determine some of
the condition and some of the risks, what
is the best type of imaging to make that
determination to make the proper
diagnosis? So one requires a relatively
advanced imaging to make these measures.
Probably, the most complete approach is
to use PET/MR imaging, so Combined
Positron Emission Tomography and MR
imaging
where the MR can give us information on
the volume and the connectivity of the
amygdala and associated brain structures.
And the PET gives us information on the
metabolic activity of the
amygdala and that's the contemporary
approach that we're using to studying.
This is not a clinically used
approach rather complex and available to
a small number of centers across the
world but in terms of driving the
science, it's a verym very useful tool and
an exciting one. Where can we learn more
online about some of this imaging and
some more about some of these
developments that were presented in this
year's sessions? Absolutely. A lot of the
exciting presentations are available at
the American Heart Association website.
Well thanks for taking the time and
talking with us today Dr. Tawakol. I'm
hoping you'll come back and talk with us
in the future. It's my pleasure. You've been
listening to Health Professional Radio.
I'm your host Neal Howard. Transcripts
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