Washington: Exercise is a real boon - clearing the mind, pumping in more blood and oxygen to the brain and doing much more, latest research suggests.

David Bucci, associate professor of psychology at Darmouth College, and his collaborators have identified a gene which seems to mediate the degree to which exercise benefits the brain and in mental illness too.

Bucci began his pursuit of the link between exercise and memory with attention deficit hyperactivity disorder (ADHD), among the commonest childhood psychological disorders, the journal Neuroscience reports.

"The notion of pumping children full of psycho-stimulants at an early age is troublesome," Bucci cautions. "We frankly don't know the long-term effects of administering drugs at an early age - drugs that affect the brain - so looking for alternative therapies is clearly important."

Based on observations of ADHD children in University of Vermont summer camps, athletes or team sports players were found to respond better to behavioural interventions than more sedentary children, according to a Dartmouth statement.

Accordingly, they investigated a mechanism through which exercise seems to improve learning and memory, known as the "brain derived neurotrophic factor" (BDNF), also involved in growth of the developing brain.

The degree of BDNF expression in exercising rats correlated positively with improved memory, and exercising as an ­adolescent had longer lasting effects compared to the same duration of exercise, but done as an adult.

"The implication is that exercising during development, as your brain is growing, is changing the brain in concert with normal developmental changes, resulting in your having more permanent wiring of the brain in support of things like learning and memory," says Bucci.