New York, Oct 12 (IANS): Lithium, a drug used successfully for decades to treat adults with the bipolar disorder, can also be safe and effective for children suffering from the chronic brain condition marked by spontaneous, changing bouts of elation and depression, says a new study.

Doctors can now more confidently add lithium to the armamentarium of available treatments for this vulnerable population -- at least in the short term, the researchers said..

"Lithium is the grandfather of all treatments for bipolar disorder, but it has never been rigorously studied in children," said Robert Findling, professor of psychiatry and behavioural sciences at the Johns Hopkins University School of Medicine in Baltimore, US.

Bipolar disorder affects approximately one percent of teenagers and is one of the leading causes of disability in adolescence, the study pointed out.

To test whether lithium is safe and as effective at treating bipolar disorder for children as it is for adults, Findling and his colleagues conducted a study involving 81 patients seen at nine academic medical centres across the United States.

The participants, split roughly equally between sexes, ranged in age from seven to 17 and had all been diagnosed with bipolar disorder.

After undergoing a "washout" period for those already taking ineffective medication for this condition, 53 children started a regimen of lithium at a standard dose, then gradually increased to a maximum tolerated dose over the next eight weeks if mood symptoms were not controlled.

The remaining 28 patients received placebo.

Results showed that the patients on lithium experienced far more significant improvement in their symptoms over eight weeks compared with those on the placebo.

The study was published in the journal Pediatrics.