Aerobic Exercise Improves Cognitive Function
Study focuses on abilities of older men and women
Friday, January 19, 2001
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The team of Duke University Medical Center researchers who
demonstrated in late 1999 that aerobic exercise is just as
effective as medication in treating major depression in the
middle-aged and elderly has now reported that the same exercise
program also appears to improve the cognitive abilities of these
patients.
"What we found so fascinating was that exercise had its beneficial
effect in specific areas of cognitive function that are rooted in
the frontal and pre-frontal regions of the brain," said James
Blumenthal, Duke psychologist and study principal
investigator.
The results of the Duke study, funded by a grant from the National
Institute of Mental Health (NIMH), were published in the January
issue of the .
"The implications are that exercise might be able to offset some of
the mental declines that we often associate with the aging
process," Blumenthal said. "Further studies are warranted not only
to clarify specific mental processes that are improved by exercise,
but to better understand the underlying mechanisms of these
improvements."
While it is unclear why exercise would improve mental functioning
of these patients, Blumenthal believes that it could be influenced
by the improved flow of oxygen-rich blood to specific regions of
the brain.
"We know that in general, exercise improves the heart's ability to
pump blood more effectively, as well as increases the blood's
oxygen-carrying capacity," Blumenthal said. "It is thought that one
of the reasons why the elderly - especially those with coronary
artery disease or hypertension - tend to suffer some degree of
cognitive decline is in part due to a reduction in blood flow to
the brain.
"So it may be that just as exercise improves muscle tone and
function, it may have similar effects on the brain," he said.
In the original exercise and depression study, dubbed SMILE
(Standard Medical Intervention and Long-term Exercise), the
researchers followed 156 patients between the ages of 50 and 77 who
had been diagnosed with major depressive disorder (MDD). They were
randomly assigned to one of three groups: exercise, medication or a
combination of medication and exercise.
The exercise group spent 30 minutes either riding a stationary
bicycle or walking or jogging three times a week. The
anti-depressant used by the medication group was sertraline (trade
name Zoloft), which is a member of a class of commonly used
anti-depressants known as selective serotonin re-uptake
inhibitors.
To the surprise of the researchers, after 16 weeks, all three
groups showed statistically significant and identical improvement
in standard measurements of depression, implying that exercise was
just as effective as medication in treating major depression.
Not only did study participants take a standard battery of tests
for depression, they took a series of standardized tests aimed at
measuring the cognitive abilities of four separate domains: memory,
executive functioning, attention/concentration and psychomotor
speed. These tests were taken before enrolling in the trial and
four months later.
After comparing the test results from the 42 members of the
exercise group to the 42 members of the medication group, the
researchers found that exercise seemed to have a beneficial effect
on selective areas of cognitive functioning, and that the level of
depression also seemed to play a role.
"The participants with milder depression at the beginning of the
trial were more likely to show an improvement in the executive
functioning domain, while those with moderate to severe depression
showed less improvement," Blumenthal said.
To better understand this phenomenon, Blumenthal and his colleagues
are now enrolling participants in another NIMH-funded study, called
SMILE-II. Participants must be clinically depressed, over the age
of 50, and must be physically able to exercise.
The research team included, from Duke, Parinda Khatri, Michael
Babyak, Steve Herman, Teri Baldewicz, David J. Madden, Dr. Murali
Doraiswamy, Dr. Robert Waugh, and Dr. Ranga Krishnan. Edward
Craighead, University of Colorado at Boulder, was also a member of
the team.For more information on the SMILE-II study, call Alisha Hart at
(919) 681-2612.
