Daily physical activity may reduce the risk of Alzheimer's disease and cognitive decline, even in people over the age of 80, according to a new study by neurological researchers from Rush University Medical Center that will be published in the online issue of Neurology, the medical journal of the American Academy of Neurology on April 18.

"The results of our study indicate that all physical activities including exercise as well as other activities such as cooking, washing the dishes, and cleaning are associated with a reduced risk of Alzheimer's disease," said Dr. Aron S. Buchman, lead author of the study and associate professor of neurological sciences at Rush. "These results provide support for efforts to encourage all types of physical activity even in very old adults who might not be able to participate in formal exercise, but can still benefit from a more active lifestyle."

"This is the first study to use an objective measurement of physical activity in addition to self-reporting," said Dr. Aron S. Buchman, lead author of the study and associate professor of neurological sciences at Rush. "This is important because people may not be able to remember the details correctly."

To measure total daily exercise and non-exercise physical activity, researchers from Rush asked 716 older individuals without dementia with an average age of 82 to wear a device called an actigraph, which monitors activity, on their non-dominant wrist continuously for 10 days.

All exercise and non-exercise physical activity was recorded. Study participants also were given annual cognitive tests during this ongoing study to measure memory and thinking abilities. Participants also self-reported their physical and social activities.

Study participants were individuals from the Rush Memory and Aging Project, an ongoing, longitudinal community study of common chronic conditions of old age.

Over a mean of 3.5 years of follow-up, 71 participants developed Alzheimer's disease.

The research found that people in the bottom 10 percent of daily physical activity were more than twice as likely (2.3 times) to develop Alzheimer's disease as people in the top 10 percent of daily activity.

The study also showed that those individuals in the bottom 10 percent of intensity of physical activity were almost three times (2.8 times) as likely to develop Alzheimer's disease as people in the top percent of the intensity of physical activity.

"Since the actigraph was attached to the wrist, activities like cooking, washing the dishes, playing cards and even moving a wheelchair with a person's arms were beneficial," said Buchman. "These are low-cost, easily accessible and side-effect free activities people can do at any age, including very old age, to possibly prevent Alzheimer's."

The number of Americans older than 65 years of age will double to 80 million by 2030.

"Our study shows that physical activity, which is an easily modifiable risk factor, is associated with cognitive decline and Alzheimer's disease. This has important public health consequences," said Buchman.

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