New York, Feb 25 (IANS): The hyperactive behaviour exhibited by children with attention deficit disorder may actually prove beneficial for their memory.

Children with attention deficit/hyperactivity disorder (ADHD) may benefit cognitively from behaviours like squirming or fidgeting, said the researchers.

The results showed that kids affected with ADHD moved up to 25 percent more when trying to solve a problem.

The findings suggest that making ADHD kids sit still may be counterproductive.

"It's another piece of evidence that the hyperactive behaviour more and more seems to be purposeful for them," said Michael Kofler, assistant professor at Florida State University in the US.

Children with ADHD are able to retain information, which they use daily. But they often have difficulty with what's called working memory, meaning the updating or mentally rearranging of information in the mind.

In the study, published online in the Journal of Attention Disorders, the researchers worked with 25 boys and girls with ADHD, ages eight to 12, and devised two types of tests to show a cause-and-effect relationship between working memory demands and hyperactivity in ADHD.

The first test required students to remember where a series of dots appeared on a screen and mentally reordering them based on colour.

The other involved remembering a series of numbers and letters, and mentally reordering them, numbers first from smallest to biggest, then the letter. There were between three and six items to remember and reorder throughout the tests.

The students were given each test multiple times and the predictability of difficulty differed with each test.

In the less difficult version, they were told how many items they had to remember, and took the test in order. In the difficult version, the amount of information to remember in working memory was random.

The children fidgeted and moved during all the tests, as expected because all the tests were mentally challenging.

But they moved up to 25 percent more when they couldn't predict how many items they had to remember, the study said.