Use of narcotics like ecstasy, ice and speed for a long time leads to brain damage, a study by Australian doctors has said.

Doctors at the Royal Perth Hospital scanned the brains of 30 patients who were treated for problems related to amphetamine use.

The patients were mostly men, with an average age of 26 years, and most had a history of ice, speed or ecstasy use that spanned several years.

A majority of the patients told doctors they were suffering from lack of concentration and mood swings. Half admitted they had memory failures.

Six patients showed signs of brain damage, the Herald Sun reported Sunday.

MRI scans of the six showed abnormalities in the form of an unidentified bright object, said Daniel Fatovich, a professor at the hospital's Centre for Clinical Research in Emergency Medicine.

The research has been published in the latest edition of the Medical Journal of Australia.