Oct 24, 2012 by TAMMY McKENZIE
Physical Exercise Still Beats Mental Workouts For Keeping The Brain In Top Form
Regular physical exercise appears to trump mental memory games when it comes to protecting the brain from shrinking, an otherwise natural process that occurs with age.
Conversely, mentally and socially stimulating activities, long believed to stimulate the brain, had no major effect on preventing brain shrinkage, according to a study published in the journal Neurology.
Obese individuals have more water in the amygdala - a part of the brain involved in eating behaviour. There is also smaller orbitofrontal cortices in obese individuals, important for impulse control and also involved in feeding behaviour (Brain Research, in press). It could mean that there are less neurons, or that those neurons are shrunken.
This relatively large brain-imaging study, which included brain scans using magnetic resonance imaging (MRI), involved more than 600 people in Scotland between the ages 70 and 73. The researchers found a strong and direct correlation revealing that as physical exercise increases, brain shrinkage decreases.
"People in their seventies who participated in more physical exercise, including walking several times a week, had less brain shrinkage and other signs of aging in the brain than those who were less physically active," said lead author Alan J. Gow of the University of Edinburgh in Scotland. "On the other hand, our study showed no real benefit to participating in mentally and socially stimulating activities on brain size, as seen on MRI scans, over the three-year time frame."
The research tapped into a respected longitudinal aging study called the Lothian Birth Cohort Study 1936, which, in 1947, tested the intelligence of more than 1,000 children born in 1936 and then has followed up with periodic assessments. This latest analysis entailed a health survey conducted when 638 subjects were 70 and then an MRI scan when they were 73.
The subjects provided details of their daily activities -- from moving to do only basic chores, to keeping fit with heavy exercise or competitive sports -- as well as non-physical social and leisure endeavors. Those most devoted to exercise showed both better brain circuitry connections and less brain shrinkage compared with the least-active subjects. This was regardless of initial IQ or social class status.
There was, however, "no support for a beneficial effect of more intellectually challenging or socially orientated activities," the researchers wrote, at least in terms of warding off brain shrinkage.
Mild Alzheimer's disease patients with higher physical fitness have larger brains compared to mild Alzheimer's patients with lower physical fitness, according to a study published in the July 15, 2008, issue of Neurology.
"People with early Alzheimer's disease may be able to preserve their brain function for a longer period of time by exercising regularly and potentially reducing the amount of brain volume lost. Evidence shows decreasing brain volume is tied to poorer cognitive performance, so preserving more brain volume may translate into better cognitive performance," said study author Jeffrey M. Burns, MD.
Gow said his group hasn't established a biological reason for why exercise can give the brain such a physical workout. Nor could they rule out the possibility that a healthy brain enables those elderly subjects to exercise more, and not that exercise maintains the brain.
"To be definitive, we do of course need more large-scale trials examining the effects of physical activity interventions," to determine which factors determine what, Gow told LiveScience. "We are following up the same individuals [for] repeat lifestyle assessments and brain scans, which will allow us to examine the direction of the associations in more detail."
Nevertheless, both physical exercise and non-physical leisure and social pursuits have so many other benefits -- for the former, preventing chronic diseases; for the latter, combating depression and fatigue -- that there's no harm in pursuing both at any age.
"We have always been in search of the drug or the magic pill to help treat brain disorders," noted Kirk I. Erickson, an assistant professor of psychology at the University of Pittsburgh. "But really what we are after may be, at least partially, even simpler than that. Just by walking regularly, and so maintaining a little bit of moderate physical activity, you can reduce your likelihood of developing Alzheimer's disease and [can] spare brain tissue."
Dr. Steven V. Pacia, chief of neurology at Lenox Hill Hospital in New York City, described such research and findings as both "intriguing" and an "undoubtedly positive message to send to the public."
"My first reaction to studies like this is that only in America do we have to prove to people that it's good to walk," he said with a chuckle.
"But it stands to reason that being active as we age is going to have a beneficial effect on the brain, just as being inactive is going to have a negative impact," Pacia noted. "Because the brain lives in the environment of the body."
Tammy McKenzie is a certified personal trainer and fitness specialist with a speciality in women's fitness.