U. S. researchers said on Thursday that a finding that might open new vistas for treating addiction stated that extended cocaine exposure can lead to changes in the way genes are switched on and off in the brain that are permanent.

Ian Maze of Mount Sinai School of Medicine in New York and colleagues conducted a study in mice. Two groups of mice were taken and one group of young mice was administered doses of cocaine on repetitive basis and another group repeated doses of saline before being given a single dose of cocaine.

At the end of the study the team concluded that by suppressing gene 9A an enzyme that has a significant role in switching genes off and on reward circuits in the brain are altered.

Dr Nora Volkow, director of the National Institute on Drug Abuse, part of the National Institutes of Health, said, "This finding is opening up our understanding about how repeated drug use modifies in long-lasting ways the function of neurons."

Maze and colleagues also concluded through the study that by increasing the activity of gene 9A these effects could be reversed.