MONDAY, April 11 (HealthDay News) -- If you're typing on a computer while talking on the phone and enjoying a cappuccino, know that you may not be able to focus on so many things at once forever.

In fact, new research finds that older people have slightly less of an ability to multitask, possibly because they can't refocus as well after getting interrupted.

The difference in multitasking abilities between younger and older people wasn't huge: older participants who took part in the study were able to focus after a mind-diverting distraction 88 percent of the time, compared to 90 percent among younger people.

Still, when they're distracted, "older adults pay too much attention to the irrelevant information" in contrast to the task at hand, said study co-author Dr. Adam Gazzaley, a neuroscientist and associate professor at the University of California, San Francisco.

In the report, which appears in this week's issue of the Proceedings of the National Academy of Sciences, researchers looked at how much people were able to focus when they are trying to do a task and something else vies for their attention. They wanted to specifically study how multitasking abilities evolve over the course of a lifetime.

Previous studies have shown that older people "don't process information as well as younger adults do," Gazzaley said. "They very frequently tell you that they have this experience: they're sitting in the living room, and they leave the couch to get something out of the refrigerator. They arrive there, and have no idea what they're doing there."

This, of course, can also happen to young people, but the question is what makes it more common in older people, so much more common that there's a word for it: "senior moment."

In the study, researchers recruited 20 older people -- average age 69 -- to undergo brain scans as they looked at images of a nature scene. Then they saw nothing over several seconds or were shown a brief image of a face. Some were told to not just look at the image but also determine if it was of a male over the age of 40.

At the end of the exercise, which was repeated several times, the subjects were instructed to try to match the image that had been shown first.

The researchers dumped the results from three participants due to problems, and then compared the rest to those from younger people with an average age of 25.

Older adults were able to successfully refocus and get the right answer 96 percent of the time with no interruption and 88 percent of the time when they had to think about the second image, Gazzaley said. In younger adults, the numbers were 94 and 90 percent, respectively.

For older people, the problem seems to be that they have "trouble switching back" to the issue at hand and disengaging from the interruption, Gazzaley said.

The challenge of multitasking is that people can't really focus on multiple things at once, said Russell A. Poldrack, a professor of psychology and neurobiology at the University of Texas at Austin. "We are almost always switching back and forth between the different tasks, and there is a cost to this switching, which is why people are nearly always worse when they try to multitask compared to focusing on single tasks."

What to do if you have to multitask? "If one is in a situation where multitasking is necessary, then the best way to improve it will likely be to improve general brain health," Poldrack said, "and the best way that we know of to improve brain health is aerobic exercise."

More information

Check images of the brain at Harvard University's Whole Brain Atlas.