An Australian study has found lithium to be better at protecting the brains of bipolar patients than that of a newer and more popular antipsychotic drug.

A treatment for bipolar disorder introduced in the 1970s is much more effective at protecting the brains of patients than some newer antipsychotic medications, an Australian study has found.

The Deakin University and Barwon Health study, published in the journal Translational Psychiatry, tested the effects of mood stabiliser lithium compared with those of antipsychotic drug
quetiapine - now a more commonly prescribed alternative - on patients who had had a manic episode for the first time.

It found lithium was superior at protecting the brain tissue.

Bipolar disorder is a mental illness involving a loss of brain volume and the more episodes the patient has the more they lose.

Researchers at Deakin evaluated people who had a first episode of mania; half were treated with lithium and half with quetiapine.

Their symptoms and brain scans were compared at the start of the trial, after three and then 12 months.

The scans showed lithium was more effective than quetiapine at slowing the loss of white matter brain tissue, said Professor Michael Berk, Director of Deakin's Centre for Innovation in Mental and Physical Health and Clinical Treatment at Barwon Health.

"Brain scans on first episode mania patients at three and 12 months showed lithium was more effective than quetiapine at slowing the progression of white matter volume reduction."

Prof Berk says the data supports the continuing use of lithium from the earliest stages of disorder - challenging some guidelines that propose lithium only for use after several episodes.

Lithium has fallen out of favour over the years because it has a lot of side-effects and the attractiveness of the newer medications and marketing.

While it does need to be monitored carefully, its use is supported by the Royal Australian and New Zealand College of Psychiatrists (RANZCP).

If it is the most effective drug where a person can tolerate it then it should be amongst the first things considered when treating patients with this serious and often debilitating condition, RANZCP president Professor Malcolm Hopwood said.

"This study would support that lithium may indeed be one of those treatments we should be utilising early in the condition," Prof Hopman said.