Researchers say there is a link between the number of steps people take each day and dementia. A study found in the Journal of the American Medical Association shows exercise can help preserve brain function.

"They took a huge population and gave them step counters and studied a lot of information about them and looked at who develops dementia and who doesn't," says Dr. Marc Otten, a neurosurgeon at Orthopaedic & Neurosurgery Specialists.

Participants in the UK who took 3,800 steps a day, which is 1.8 miles, reduced their risk of dementia by 25%.

Those who took 9,800 steps, which is nearly five miles, reduced their risk by half.

Dr. Otten says it is likely that exercise helps keep the brain's electrical system running and help purify the brain.

"Cleaning out the waste, there's absolutely that process going on constantly, so keeping that blood pumping is also removing that waste," says Dr. Otten.