Researchers from the University of Pittsburgh analyzed the relationship between walking and brain structure in 426 people: 299 cognitively healthy adults, 83 people with MCI, and 44 people with Alzheimer’s dementia. The researchers monitored how far each of the patients walked in a week. After 10 years, all patients underwent 3-D MRI exams to identify changes in brain volume.
When they entered the study in 1989-1990, participants were asked how many city blocks they walked in an average week, whether for exercise, chores, or any other reason. Follow-up questionnaires every three years showed that the number of blocks walked remained steady over time. In addition, participants were given a brief test of cognitive skills at various times throughout the study, with the final one five years after the second MRI scan.
As shown by MRI, brain volume was preserved in healthy adults who walked at least 72 city blocks, or 6 miles, per week. Cognitive exam scores showed walking six miles a week was associated with a 50% decline in Alzheimer’s risk over 13 years. Walking more than 72 blocks a week offered no additional benefit. Cognitively impaired people needed to walk at least 58 city blocks, or approximately 5 miles, per week to maintain brain volume and slow cognitive decline. Over 10 years, scores on the 30-point cognitive test dropped by an average of five points in cognitively impaired patients who were sedentary, compared with one point in those who walked 5 miles per week.
The relationship between walking and preserved brain volume persisted even after the analysis was adjusted to take into account other risk factors for dementia, including age, gender, and high blood pressure.
The findings showed across the board that greater amounts of physical activity were associated with greater brain volume.
Michael S. Rafii, MD, PhD
Associate Medical Director, Alzheimer’s Disease Cooperative Study
*Raji CA, et al “Physical activity and brain structure in healthy aging and cognitive impairment” RSNA 2010.