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Summary:
How lifestyle affects mood.
Maybe, despite the complex
biological links between
heart and mind, it all comes
down to lifestyle factors.
"We think exercise is a
critical factor in
modulating the outcome,"
says Duke University chief
of psychiatry K. Rama Ranga
Krishnan, M.D. "It works
directly and indirectly on a
number of factors common to
depression and heart
disease. It helps depression
and it helps cardiac
disease." And it does so at
many points in paths of both
conditions. Adds Emory
cardiologist Viola Vaccarino,
M.D.: "Exercise and omega-3
fatty acids are recommended
for everyone. But they may
be especially critical for
those with depression."
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Animal studies show that
exercise directly alters
levels of neurohormones
such as norepinephrine in
the brain’s frontal cortex
and in the hippocampus.
Both are brain regions
involved in circuits of
emotion.
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Exercise appears to
stimulate the vagus nerve,
the major channel of the
parasympthetic half of the
autonomic nervous system.
It stabilizes heart
function and
counterbalances the
sympathetic hyperactivity
identified in depression.
It also improves function
of the brain's
emotion-sensing network.
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By acting on neurohormones
that govern the stress
response, exercise
improves the ability of
the body to tolerate
stress.
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Exercise stimulates
production and expression
of the nerve growth factor
BDNF (brain-derived
neurotrophic factor). This
protein, elaborated in
brain cells, may be the
final common pathway by
which all antidepressant
therapies work. BDNF helps
rewire the brain; it
induces brain cells to
reinforce old connections
and to forge new ones,
restoring memory and
cognitive flexibility to
the depressed.
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Exercise directly reverses
insulin resistance,
restoring the body’s
sensitivity to this
important hormone.
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Exercise directly burns
energy, promoting weight
loss.
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Recent studies show that
low-intensity exercise
boosts immunity and
reduces levels of the
inflammatory marker
C-reactive protein—even in
people genetically
predisposed to develop
cardiovascular disease.
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Over the long term,
exercise also stimulates
the growth of new blood
vessels, so-called
collateral circulation,
boosting the general
function of both brain and
heart by maximizing
delivery of oxygen.
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Raising heart rate by
exercise delivers more
blood to the brain,
feeding it nutrients and
oxygen that boost mental
functions.
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Exercise elevates mood by
psychological means as
well as physiological
ones. It changes people’s
perception of themselves,
providing a sense of
personal mastery. It also
reduces negative thinking.
 If
there’s one person
associated with the role of
exercise in depression it’s
James Blumenthal, Ph.D.,
professor of medical
psychology at Duke
University. He was one of
the first to test aerobic
exercise in people with
moderate to severe
depression. The patients,
sedentary men and women over
age 50, worked out for 30
minutes three times a week
in groups. Their response
was compared with that of
similarly depressed patients
who received either standard
therapy with Zoloft or drug
and exercise combined.
Patients in all three groups
experienced equally
significant reductions in
depression symptoms, and
remission rates were
comparable–60 percent to 65
percent. Surprisingly,
combining two effective
treatments, drug and
exercise, added no benefit.
In fact, the only difference
among the groups was in
speed of response. The
medication-alone group began
improving within a few
weeks; exercisers took a few
weeks longer. But the
effects of exercise lasted
longer. Six months after
treatment ended, fewer
exercisers had relapsed into
depression. Among the
patients no longer
depressed, only 8 percent of
the exercisers relapsed,
compared with over 30
percent in the medication
group. "That was a big
surprise," Dr. Blumenthal
confides. Contrary to his
own expectations, he found
that exercise was beneficial
against severe depression.
"Those with moderate to
severe depression responded
as well as those with mild
depression," he says.
Exercise undertaken to
combat depression improves
aerobic capacity and
cardiovascular fitness, and
Dr. Blumenthal makes a
strong case for aerobic
activities such as walking
and jogging. "It was a
surprise to us but we found
that the largest
improvements in aerobic
capacity correlated with the
greatest reductions in
depression."
How much exercise is
enough?
 "Our
data show that 30 minutes of
aerobic exercise three times
a week is sufficient for
reducing depressive
symptoms," says Blumenthal.
That’s the minimum
recommended for
cardiovascular benefit.
Patients who responded well
to exercise and maintained
their regimen had a much
smaller risk of relapsing.
"We found an inverse
relationship between
exercise and the risk of
relapsing," says Blumenthal.
"The more one exercised, the
less likely one would see
their depressive symptoms
return."
That has led him to
enunciate what he calls the
50-50 rule. "Exercise was a
significant predictor of
being free of depression at
the end of follow-up," he
says. "For every 50 minutes
of exercise a week there is
a 50 percent decrease in the
likelihood of being
depressed."
Article published with
permission of
www.psychologytoday.com
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