New York, Mar 25 (IANS): Want to keep a sharp memory in old age? A study has found that moderate to intense regular exercise in old age may delay brain aging by 10 years.

According to the study, the people who reported light to no exercise -- their brain aged 10 years more than the people who reported moderate to intense exercise.

"The number of people over the age of 65 in the US is on the rise, meaning the public health burden of thinking and memory problems will likely grow," said study author Clinton B Wright from University of Miami, US.

"Our study showed that for older people, getting regular exercise may be protective, helping them keep their cognitive abilities longer," Wright added in the paper published in the online journal of Neurology.

The team looked at data on 876 people who were asked how long and how often they exercised during the two weeks prior to that date.

An average of seven years later, each person was given tests of memory and thinking skills and a brain MRI and five years after that they took the memory and thinking tests again.

Of the group, 90 percent reported light exercise or no exercise, which included activities such as walking and yoga. They were placed in the low activity group.

The remaining 10 percent reported moderate to high intensity exercise, which included activities such as running, aerobics, or calisthenics. They were placed in the high activity group.

The findings showed, low activity levels showed a greater decline over five years compared to those with high activity levels on tests of how fast they could perform simple tasks and how many words they could remember from a list.

The difference was equal to that of 10 years of aging. The difference also remained after researchers adjusted for other factors that could affect brain health, such as smoking, alcohol use, high blood pressure and body mass index.