It's commonly assumed that physical exercise is the key to staying healthy as you get older. Yet cognitive decline is just as common as physical decline and may even cause more difficulties in everyday life - so why aren't aging adults performing cognitive exercises?

In a new study, authors hypothesized that a mere 10 hours of visual speed of processing training would prevent age-related declines and potentially improve cognitive processing speed. Using a commercial video game designed to improve the speed and quality of mental processing abilities, they conducted a randomized study of 681 patients. After 10 to 14 hours of exercise, results showed that the natural decline of a range of cognitive skills was delayed and, in some cases, by up to seven years. On average, participants' minds were three years "younger" a year after the study.

"From just 10 to 14 hours of training, that's quite a lot of improvement," said Fredric Wolinsky, lead author and professor at the University of Iowa's College of Public Health.

After randomly separating participants into four groups, Wolinsky and his colleagues divided them again into two categories: those ages 50 to 64 and those over 65. Over the course of five to eight weeks, one group was given computerized crossword puzzles to complete, while the other groups played Road Tour, a commercially available video game.

The video game Road Tour is designed to test a player's mental processing speed, requiring the player to identify and match a picture of a vehicle (a car or a truck) at the center of the screen with a series of road signs, one of which is a Route 66 road sign, displayed in surrounding circles. In order to progress to higher levels, a player must correctly identify the vehicle type while also remembering the position of the Route 66 sign, which is presented alongside a number of incorrect, or "distractor," signs.

"The way we challenge people is that eventually we show the vehicle and signs for less time on the screen, and over time, we increase the number of distractor signs," explained Wolinsky.

His study rests on several general assumptions, the first being that age-related cognitive decline is common. In fact, research suggests that age-related cognitive decline begins relatively early in adulthood - certainly before age 60 in healthy educated adults - and the magnitude of age-related decline may accelerate at older ages. Wolinsky and his colleagues also based their research on an assumption that processing speed plays an early and central role in the cascading process that leads to many limitations. Finally, the prevalence of PCs in people's homes meant many of Wolinsky's patients could use the software in private and at convenient times.

It is this final assumption that helps to render the results of the study so powerful. Anyone with access to a computer can replicate the training used in the study and improve their own cognitive function today.

The results of the new study were published May 1 in the journal PLOS ONE.