Exercise on the Brain

[manuelm...@gmail.com]

Feeling a little less mentally quick than you did a few years ago?
Maybe you are among the many people who do "brain exercises" like
sudoku to slow the cognitive decline associated with aging. We've got
a better suggestion.

Computer programs to improve brain performance are a booming
business.
In the United States, consumers are expected to spend $80 million
this
year on brain exercise products, up from $2 million in 2005.
Advertising for these products often emphasizes the claim that they
are designed by scientists or based on scientific research. To be
charitable, we might call them inspired by science -- not to be
confused with actually proven by science.


Environmental enrichment does improve mental function in laboratory
animals. Rodents and monkeys that get playmates or toys learn to
complete a variety of tasks more easily, at all ages. They also have
larger brains, larger brain cells and more synaptic connections than
animals raised alone in standard cages. But here's the rub: standard
laboratory environments are tremendously boring. Lab animals rarely
need to search for food or avoid predators. In contrast, most of us
get plenty of everyday stimulation in activities like finding a new
address, socializing with friends or navigating the treacherous
currents of office politics. Animal enrichment research may be
telling
us something important not about the positive effects of stimulation,
but about reversing the negative effects of deprivation.


Another line of evidence cited by marketers comes from studies of
elderly people who improve certain skills by practicing a challenging
computer-based task. Although most programs work to some extent, the
gains tend to be specific to the trained task.


That is, practice can certainly make people better at sudoku puzzles
or help them remember lists more accurately. The improvement can even
last for years. Similarly, people tend to retain skills and knowledge
they learned thoroughly when they were younger. Unless the activities
span a broad spectrum of abilities, though, there seems to be no
benefit to general mental fitness.


For people whose work is unstimulating, having mentally challenging
hobbies, like learning a new language or playing bridge, can help
maintain cognitive performance. But the belief that any single brain
exercise program late in life can act as a quick fix for general
mental function is almost entirely faith-based.


One form of training, however, has been shown to maintain and improve
brain health -- physical exercise. In humans, exercise improves what
scientists call "executive function," the set of abilities that
allows
you to select behavior that's appropriate to the situation, inhibit
inappropriate behavior and focus on the job at hand in spite of
distractions. Executive function includes basic functions like
processing speed, response speed and working memory, the type used to
remember a house number while walking from the car to a party.


Executive function starts to decline when people reach their 70s. But
elderly people who have been athletic all their lives have much
better
executive function than sedentary people of the same age. This
relationship might occur because people who are healthier tend to be
more active, but that's not the whole story. When inactive people get
more exercise, even starting in their 70s, their executive function
improves, as shown in a recent meta-analysis of 18 studies. One
effective training program involves just 30 to 60 minutes of fast
walking several times a week.


Exercise is also strongly associated with a reduced risk of dementia
late in life. People who exercise regularly in middle age are one-
third as likely to get Alzheimer's disease in their 70s as those who
did not exercise. Even people who begin exercising in their 60s have
their risk reduced by half.

How might exercise help the brain? In people, fitness training slows
the age-related shrinkage of the frontal cortex, which is important
for executive function. In rodents, exercise increases the number of
capillaries in the brain, which should improve blood flow, and
therefore the availability of energy, to neurons. Exercise may also
help the brain by improving cardiovascular health, preventing heart
attacks and strokes that can cause brain damage. Finally, exercise
causes the release of growth factors, proteins that increase the
number of connections between neurons, and the birth of neurons in
the
hippocampus, a brain region important for memory. Any of these
effects
might improve cognitive performance, though it's not known which ones
are most important.


So instead of spending money on computer games or puzzles to improve
your brain's health, invest in a gym membership. Or just turn off the
computer and go for a brisk walk.