Exercise
increases brain size
NICM, Western Sydney University
Aerobic exercise can improve memory function and maintain brain
health as we age, a new Australian-led study has found.
In a first of its kind international collaboration, researchers
from Australia's National Institute of Complementary Medicine at Western Sydney
University and the Division of Psychology and Mental Health at the University
of Manchester in the UK examined the effects of aerobic exercise on a region of
the brain called the hippocampus, which is critical for memory and other brain
functions.
Brain health decreases with age, with the average brain
shrinking by approximately five per cent per decade after the age of 40.
Studies in mice and rats have consistently shown that physical
exercise increases the size of the hippocampus but until now evidence in humans
has been inconsistent.
The researchers systematically reviewed 14 clinical trials which examined the brain scans of 737 people before and after aerobic exercise programs or in control conditions.
The participants included a mix of healthy adults, people with
mild cognitive impairment such as Alzheimer's and people with a clinical
diagnosis of mental illness including depression and schizophrenia. Ages ranged
from 24 to 76 years with an average age of 66.
The researchers examined effects of aerobic exercise, including
stationary cycling, walking, and treadmill running. The length of the
interventions ranged from three to 24 months with a range of 2-5 sessions per
week.
Overall, the results -- published in the journal NeuroImage --
showed that, while exercise had no effect on total hippocampal volume, it did
significantly increase the size of the left region of the hippocampus in
humans.
Lead author, NICM postdoctoral research fellow, Joseph Firth
said the study provides some of the most definitive evidence to date on the
benefits of exercise for brain health.
"When you exercise you produce a chemical called
brain-derived neurotrophic factor (BDNF), which may help to prevent age-related
decline by reducing the deterioration of the brain," Mr Firth said.
"Our data showed that, rather than actually increasing the
size of the hippocampus per se, the main 'brain benefits' are due to aerobic
exercise slowing down the deterioration in brain size. In other words, exercise
can be seen as a maintenance program for the brain."
Mr Firth said along with improving regular 'healthy' aging, the
results have implications for the prevention of aging-related
neurodegenerative disorders such as Alzheimer's and dementia -- however further
research is needed to establish this.
Interestingly, physical exercise is one of the very few 'proven'
methods for maintaining brain size and functioning into older age.
