Fitness vs Neuro-Aging

Ian Goddard igoddard at
Tue Jan 28 20:00:28 EST 2003

Study is first to confirm link between exercise and changes in brain

CHAMPAIGN, Ill. -- Three key areas of the brain adversely affected by
aging show the greatest benefit when a person stays physically fit.
The proof, scientists say, is visible in the brain scans of 55
volunteers over age 55. 

The idea that fitness improves cognition in the aging is not new.
Animal studies have found that aerobic exercise boosts cellular and
molecular components of the brain, and exercise has improved
problem-solving and other cognitive abilities in older people. A new
study in the February issue of the Journal of Gerontology: Medical
Sciences, however, is the first to show -- using high-resolution
magnetic resonance imaging -- anatomical differences in gray and white
matter between physically fit and less fit aging humans. 

Gray matter consists of thin layers of tissue of cell bodies such as
neurons and support cells that are critically involved in learning and
memory. White matter is the myelin sheath containing the nerve fibers
that transmit signals throughout the brain. 

As people age, especially after age 30, these tissues shrink in a
pattern closely matched by declines in cognitive performance, Kramer

The authors, led by Arthur F. Kramer of the University of Illinois at
Urbana-Champaign, say that the findings "provide the first empirical
confirmation of the relationship between cardiovascular fitness and
neural degeneration as predicted" in various academic studies on aging
and cognition in both animal and human populations. 

"We found differences in three areas of the brain, the frontal,
temporal and parietal cortexes," Kramer said. "There were very
distinct differences particularly in two types of tissue, the gray
matter and white matter. Nobody has reported this before." 

A second Kramer-led study -- a meta-analysis (comprehensive data
review) of 18 previous studies -- that will be published in March in
Psychological Science, suggests that older women, especially those on
hormone-replacement therapy, benefit more cognitively than do men from
increased physical activity as they age. 

The Journal of Gerontology study involved well-educated men and women
aged 55 to 79. Their fitness ranged from sedentary to very fit,
competitive-ready athletes. Fitness was measured by results of
one-mile-walking and treadmill stress tests. Three-dimensional scans
of the participants' brains were done using MRI equipment at Carle
Foundation Hospital in Urbana. Applying voxel-based morphometry,
researchers estimated tissue atrophy in a point-by-point fashion in
the targeted regions of the brain. 

"Interestingly, we found that fitness per se didnÕt have any influence
on brain density," said Kramer, a professor of psychology and member
of the Beckman Institute for Advanced Science and Technology at
Illinois. "It is fitness as it interacts with age that has the
positive effects. Older adults show a real decline in brain density in
white and gray areas, but fitness actually slows that decline." 

In the study, most other potential negative attributes -- smoking,
diabetes, drinking, dieting, etc. -- were factored out of the data
equation, Kramer said. 

"This, to our knowledge, is the first human data providing a potential
anatomical account of the cognitive effects that we and others have
found over the years," Kramer said. "Our data also suggest that more
research is clearly needed to actually do a thorough examination of
brain structure and functioning, and the impact of interventions such
as fitness and cognitive training." 

In 1999, Kramer and colleagues reported in the journal Nature that
previously sedentary people over age 60 who walked rapidly for 45
minutes three days a week can significantly improve mental-processing
abilities that decline with age, and particularly tasks that rely
heavily on the frontal lobes of the brain. 

For their meta-analysis paper, researchers reviewed 18 intervention
studies done between 1966 and 2001 and involving hundreds of
participants ages 55 and older. Fitness training was found to show
"robust but selective benefits for cognition, with the largest
fitness-induced benefits occurring for executive-control processes." 

Few studies done in the early part of the time included women, but as
data were analyzed from later studies, Kramer said, "We found that
gender had a large effect; men simply don't benefit as much, so we
went back through our own data and asked why." 

In previous studies of mice whose ovaries had been removed, they noted
a decline in exercise and a drop in production of brain-derived
neurotropin. When mice were put back on estrogen, production of the
brain molecule increased and so did exercise activity. 

In women, Kramer said, the data showed a similar trend: Women on
estrogen replacement therapy benefited more than women not on it. 

Other main conclusions from the meta-analysis: 

* Exercise programs involving both aerobic exercise and strength
training produced better results on cognitive abilities than either
one alone. 

* Older adults benefit more than younger adults do, possibly, Kramer
said, because older adults have more to gain as age-related declines
become more prevalent. 

* More than 30 minutes of exercise per session produce the greatest
benefit, a finding consistent with many existing guidelines for

The studies were funded by the National Institute on Aging (National
Institutes of Health) and the New York-based Institute for the Study
of Aging. 

"These intriguing data suggest there may be one more possible benefit
from regular exercise," said Molly V. Wagster, program director for
the Neuropsychology of Aging, Neuroscience and Neuropsychology of
Aging Program of the NIA, which supported the work. "The study
emphasizes the importance of continued research on the potential role
that exercise might play in reducing cognitive decline with age." 

Illinois contributors to the Journal of Gerontology paper were Kramer;
postdoctoral researcher Stanley J. Colcombe; doctoral student Kirk I.
Erickson; Andrew G. Webb, professor of electrical and computer
engineering; Neal Cohen, professor of psychology; and Edward McAuley,
professor of kinesiology. Naftali Raz of Wayne State University in
Detroit also was a co-author. Colcombe and Kramer performed the
meta-analysis study. 


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