Walking frequently lowers risk for cognitive decline years later.

Almost 300 healthy adults aged 65 or older reported how much they walked per week. Nine years later they had MRI brain scans. Those who walked at least 72 blocks (estimated 6-9 miles) per week had more gray matter volume compared to those who walked less. Greater gray matter volume reduced the risk for cognitive impairment 2-fold 4 years following the MRI.

PositiveTip: Physical activity seems to set off a cascade of cellular changes that increases gray matter volume--even in the elderly.