In addition to the benefits mentioned by Professor Fanning's recent
message, an article in this week's Economist points to recent breakthroughs
in mice memory brought about by exercise. However, the mice ended up
swimming in milk and dissected, so perhaps this is a mixed message. What I
find amazing is how many miles these mice ran on their little wheels.
Hooking up all that mice energy to the electric grid could solve our energy
problems...if we don't move their cheese.
Richard
Exercise boosts mental powers, even after a mis-spent youth and middle age
IT IS never too late for the lazy and the old to get off their haunches and
exercise. This week, a study found that physical activity beginning in old
age, even after a whole life lost to sloth, can help rescue the brain from
mental decline at least in mice.
The link between taking exercise and remaining mentally astute into the
golden years is well known but not well understood. Exercise seems to
stimulate the growth of new neurons in certain parts of the brain.
Physically active animals (including humans) perform better on tests of
cognition than their inactive counterparts. But the assumption was that, at
some point, people might be past salvaging.
Perhaps not. Fred (Rusty) Gage and his team at the Salk Institute in La
Jolla, California, studied young and old adult mice. Half the mice were
given running wheels, on which they happily ran five or six kilometres a
day. The other half were denied the opportunity to exercise.
Some 35 days later, each mouse was plopped into a tub of milky water. This
water also contained a refuge, in the form of a hidden platform that was
underwater but which the mice could stand on. Mice hate swimming, so they
quickly learn to use visual cues to remember where the platform is (even
when the scientists move the platforms and the cues around a few times).
The test is about how quickly the mice can learn and remember the
whereabouts of the platform.
It turns out that how quickly they learn and remember in old age is
strongly associated with how much they had been exercising. Both groups of
elderly mice swam at about the same pace, so the time it took to find
refuge was not about improved swim speed. Yet whereas the physically fit
old-timers found the platform in about 15 seconds, the old sedentary ones
took 30 secondstwice as long. (As for the young mice, it is a sad reality
that youth gets away with a lot. Even the young sloths could remember where
the platform was in less than 15 seconds.)
The difference in performance may come down to what was going on in the
mice's brains. About a week after the water test, the mice were killed and
the researchers examined their brains, counting the numbers of new neurons.
In the elderly exercisers, about 26% of new brain cells were developing
into neurons not as large a proportion as in the younger mice, to be sure,
but significantly more than the 9.5% in their non-running counterparts.
The team also found that, under the microscope, the neurons looked just
like those developing in younger brains, suggesting they were working
properly. There had been some suggestion that perhaps older brains simply
lost their capacity for neurogenesis, but Dr Gage (who exercises daily)
says this study demonstrates otherwise. And, although it is not clear that
the new neurons are responsible for the improved performance, the evidence
certainly points in that direction. The team published their work earlier
this week in the Journal of Neuroscience.
Although this work was carried out using mice, it has been shown that
humans, like many other animals, can grow new neurons even as adults.
(Indeed, this was first demonstrated in Dr Gage's laboratory.) The
implications for people, therefore, may prove to be rather straightforward:
exercise may fight the ravages of age not just on your jowls and thighs and
gut, but in your mind as well.
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