Walking Found to Slow Progression of Alzheimer's Disease

"We found that walking five miles per week protects the brain structure over 10 years in people with Alzheimer's and MCI, especially in areas of the brain's key memory and learning centers,” said Cyrus Raji, PhD, from the department of radiology at the University of Pittsburgh (PA, USA). "We also found that these people had a slower decline in memory loss over five years.”

AD is an irreversible, progressive brain disease that slowly destroys memory and cognitive skills. According to the US National Institute on Aging (Bethesda, MD, USA), between 2.4 million and 5.1 million Americans have Alzheimer's disease. Based on current population trends, that number is expected to increase significantly over the next decade.

In cases of MCI, an individual has cognitive or memory difficulties beyond typical age-related memory loss, but not as severe as those found in AD. Approximately half of the people with MCI progress to AD. "Because a cure for Alzheimer's is not yet a reality, we hope to find ways of alleviating disease progression or symptoms in people who are already cognitively impaired,” Dr. Raji said.

For the ongoing 20-year study, Dr. Raji and colleagues examined the relationship between physical activity and brain structure in 426 people, including 299 healthy adults (mean age 78), and 127 cognitively impaired adults (mean age 81), including 83 adults with MCI and 44 adults with Alzheimer's-related dementia.

Patients were recruited from the Cardiovascular Health Study. The researchers monitored how far each of the patients walked in a week. After 10 years, all patients underwent three-dimensional magnetic resonance (3D MRI) imaging exams to identify changes in brain volume. "Volume is a vital sign for the brain,” Dr. Raji said. "When it decreases, that means brain cells are dying. But when it remains higher, brain health is being maintained.”

Moreover, patients were given the mini-mental state exam (MMSE) to monitor cognitive decline over five years. Physical activity levels were correlated with MRI and MMSE results. The analysis adjusted for age, gender, body fat composition, head size, education, and other factors.

The results revealed across the board that greater amounts of physical activity were associated with greater brain volume. Cognitively impaired people needed to walk at least 58 city blocks, or approximately five miles, per week to maintain brain volume and slow cognitive decline. The healthy adults needed to walk at least 72 city blocks, or six miles, per week to maintain brain volume and considerably reduce their risk for cognitive decline.

Over five years, MMSE scores decreased by an average of five points in cognitively impaired patients who did not engage in a sufficient level of physical activity, compared with a decrease of only one point in patients who met the physical activity requirement. "Alzheimer's is a devastating illness, and unfortunately, walking is not a cure,” Dr. Raji concluded. "But walking can improve your brain's resistance to the disease and reduce memory loss over time.”

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