Burning calories keeps you mentally fit. New research reveals that seniors who are physically active have younger brains and are less likely to develop Alzheimer's disease.

The latest MRI study reveals that participants who burned more calories have larger gray matter volume in brain regions responsible for memory and thinking. What's more, researchers found that burning calories can also stall dementia progression. The latest study revealed that participants who had mild cognitive impairment or Alzheimer's disease experienced less gray matter volume reduction over time.

Researchers said the latest study highlights the importance of physical activity in old age when the risk of developing Alzheimer's disease and other neurodegenerative disorders increase.

The latest study involved five years of data from 876 people aged 65 or older who were part of the multicenter Cardiovascular Health Study. For the study, participants underwent brain scans, periodic cognitive assessments and interviews about their level of physical activity.

Further analysis revealed that participants who burned the most calories had significantly denser gray matter volumes in the frontal temporal and parietal lobes of their brain. This is important because these brain regions are associated with learning, memory and complex cognitive tasks.

"Gray matter houses all of the neurons in your brain, so its volume can reflect neuronal health," lead researcher Cyrus Raji said in a university release. "We also noted that these volumes increased if people became more active over five years leading up to their brain MRI."

"Our current treatments for dementia are limited in their effectiveness, so developing approaches to prevent or slow these disorders is crucial," added co-study author James T. Becker, professor of psychiatry at the University of Pittsburgh School of Medicine.

Instead of waiting for significant memory loss, Raj suggests that doctors should think about putting their dementia patients "on an exercise program and then rescan later to see if there are any changes in the brain."

"Our study is one of the largest to examine the relationship between physical activity and cognitive decline, and the results strongly support the notion that staying active maintains brain health," Becker concluded.

The findings are published in the Journal of Alzheimer's Disease.