Caloric expenditure was calculated based upon study participants describing activities such as aerobics over the course of two weeks.(Photo: Justin Sullivan, Getty Images)
Anyone looking for a reason to be more active can start by worrying about their brain.
the conclusion of researchers behind a study out today showing people
who burn off the most energy have healthier, younger brains compared
with adults who do less.
Lead author Cyrus Raji of UCLA says the
researchers set out to determine how physical activity is associated
with gray matter during aging. Gray matter, also called the cerebral
cortex, gets the credit for processing much of the information we use.
It is made up of neurons and nerve fibers, and its shrinkage is a
possible cause of or contributor to dementia and Alzheimer's disease, a
fatal degenerative illness that affects 5.2 million adults in the USA.
The number of diagnoses is expected to triple by 2050.
study of 876 adults (ages ranged from 69-95), those who burned the most
calories had 5% more gray matter. The findings were presented at the
annual meeting of the Radiological Society of North America in Chicago.
The researchers used MRIs and 3-D pictures of the brain to measure
"If you want to maximize the effect on your brain, these
physical activities are something people have to start engaging in
earlier in life, in your 50s and 40s," says Raji.
activities included swimming, hiking, aerobics, jogging, tennis,
racquetball, walking, gardening, mowing, raking, golfing, bicycling,
dancing, calisthenics and riding an exercise cycle.
Those in the
top 25% for physical activities burned off 3,434 calories a week
compared with those in the bottom 25%, who burned only 348 calories a
week. It takes about 110 minutes to walk off 560 calories.
the study shows a link between activity and brain health, the findings
don't prove that activity preserves brain matter, says Dave Knopman, a
spokesman for the American Academy of Neurology.
"It could be the
people with the bigger brains are more physically active," says
Knopman, a neurology professor at the Mayo Clinic in Rochester, Minn.
patients' conditions ranged from normal cognition to Alzheimer's
dementia. Benefits were also noted in people who have mild cognitive
impairment and Alzheimer's disease, Raji says. Greater caloric
expenditure was related to larger gray matter volumes, including the
While noting that biological changes in other parts
of the brain (beyond gray matter) are also possible causes for dementia,
Joshua Willey, a neurologist at Columbia University, says this study's
focus on regions of the brain is encouraging.
"We care about the
volume of the hippocampus because that seems to be the first area that's
affected in Alzheimer's disease," Willey says. "That's the part of the
brain most of us think of in terms of short-term memory. So this is
A 2011 study of 120 previously sedentary adults
ages 55 to 80 found that those who walked around a track for 40 minutes
three days a week for a year increased the volume of their hippocampus.
Older adults assigned to a stretching routine showed no hippocampal
Walking is aerobic in nature, making the heart, lungs and large muscle groups work harder than at rest.
all of the activities examined in this study are some variation of
aerobic physical activity, which we know from other work can improve
cerebral blood flow and strengthen neuronal connections," he says.
gives the aerobic theory a thumbs-up: "People who are active are also
less likely to have diabetes, high blood pressure, are less likely to be
obese or have heart disease, all conditions associated with an
increased risk of getting dementia."