People who lead sedentary lives face higher risk of developing
dementia as they age, according to a new study.
Seniors who exercise little or not at all are 50 percent more at
risk of dementia than people who exercise regularly at a moderate or heavy
intensity, the researchers concluded.
Bicylcing slowly, gardening, ballroom dancing, and walking
briskly all constitute moderate physical activity, the U.S. Centers for Disease
Control and Prevention report.
Intense physical activity is not required to reduce a person's
risk for dementia, though. Moderate intensity is fine.
Participants in the study who were over the age of 74 received
the most protective benefit against dementia from exercise, according to the
study. Based on brain scans of the participants, those who exercised better
handled the effects of aging on the brain. The brain tends to shrink with age,
and the participants who exercised regularly had larger brains by volume than
people who were sedentary.
The study involved 3,700 participants from a federally funded
health research project that began in 1948. All participants were at least 60
years old.
The researchers evaluated how often participants participated in
physical activity and tracked them for more than 10 years. During that time,
236 participants developed dementia.
The researchers divided participants into five groups ranging
from sedentary level to highly active. The most sedentary group faced a 50
percent higher risk of developing dementia than the other four groups,
according to investigators. Even a little exercise helps stave off dementia, in
other words.
The researchers also compared brain scans and discovered a
direct relationship between brain size and exercise as people age. People who
worked out had bigger brains by volume.
Physical exercise could lead to heightened density of neuron
connections or create alternative signal pathways, which would be impeded by
brain shrinkage. In other words, more
route possibilities make blockages much less likely, like in a street system in
a city. More routes make traffic jams less likely.
Exercise encourages secretion of chemicals in the brain, such as
neurotrophic factor or BDNF, which encourage new neurons to grow and existing
neurons to be preserved. It is likely a combination of these two explanations
contributes to exercise's effect on brain volume.
Past studies have proved an association between exercise and
brain size or protecting against dementia, but studies trying to prove a
definite link have been disappointing thus far. This latest studies offers some
hope for understanding the link.
Though the link is not yet clear, doctors are already
prescribing moderate intensity exercise to patients in efforts to preserve
brain health.