COUCH potatoes take note鈥攕imple physical exercise could protect your
brain from the ravages of old age. Increased activity triggers a huge and rapid
growth in the density of the brain鈥檚 blood vessels, even in middle age, say
researchers in Wisconsin.
Previous studies had shown that young animals sprout blood vessels in the
brain after bursts of exercise. 杏吧原创s suspected that this was probably only
possible early in life. To find out if it also happens in middle age, Rodney
Swain and his colleagues at the University of Wisconsin in Milwaukee compared
the brains of middle-aged sedentary lab rats to their wheel-treading
counterparts.
The active rats had free access to a wheel for a fixed number of days,
ranging from 1 to 30. The laziest rat ran an average of only 176 metres per
night, while the most ambitious did more than 10 kilometres daily.
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Researchers looked at the rats鈥� brains via magnetic resonance imaging and
tissue staining to identify where new blood vessels formed. The density of blood
vessels in the regions controlling motor activity had increased dramatically for
active rats鈥攅ven for those with a modest exercise programme. All the
growth had taken place in the first three days of activity.
鈥淲e didn鈥檛 expect that three-day peak,鈥� says Swain. 鈥淚t shows that the brain
can make rapid changes to its oxygen supply.鈥� Following this peak, the animals
ran up to three times further each day, showing activity that mirrored the blood
vessel growth. Swain will announce the results next week at the Winter
Conference on Brain Research in Snowbird, Utah.
Because the neurons in the motor cortex and cerebellum are stepping up their
activity, they need more nutrients and oxygen, the researchers suggest, so the
brain sprouts extra capillaries to supply them. Brain regions not responsible
for motor output showed no changes.
Middle-aged rats may not be the only ones to benefit from the changes. Swain
thinks a similar explosion in capillaries would take place in human brains
within a month of taking more exercise. Importantly, this may protect against
age-related decline. 鈥淥ne of the most commonly cited features of Alzheimer鈥檚 is
a decrease in cerebral blood flow,鈥� he says. He speculates that cognitive
workouts may spark the formation of blood vessels as well.