Severely depressed people can have fewer side effects with an ultra-brief electroconvulsive therapy, research shows.

A newer treatment for severe depression is almost as effective as standard electroconvulsive therapy (ECT) but with far fewer side effects, research shows.

The University of NSW study, published in the Journal of Clinical Psychiatry, reviewed six international ECT studies involving 689 patients.

It examined the effectiveness and cognitive effects of standard ECT versus the newer ultra-brief pulse stimulation ECT.

It found while standard ECT was slightly more effective for treating depression and required one less treatment, it had significantly more side effects, said UNSW Professor of Psychiatry Colleen Loo.

The ultra-brief stimulation significantly lessened the potential for the destruction of memories formed before ECT, reduced the difficulty of recalling and learning new information after ECT and was almost as effective as the standard treatment, she said.

"This is a very important step forward because it means it is valid to use this form of ECT in clinical practice," she told AAP.

"It's the first and only analysis that has pulled together all the studies."

Prof Loo said less than half of Australia's hospitals offer ultra-brief stimulation, but the study showed some patients will be able to get fully well with it and have less side effects.
The standard ECT should still be an option particularly where urgency of response was paramount.

While the patient is under general anaesthesia, ECT delivers a finely controlled electric current to the brain's prefrontal cortex, which is underactive in people with depression.

Ultra-brief ECT delivers staccato pulses of electricity, with each pulse on for only a very short time, reducing the stimulation of brain tissue by a third.

"Unfortunately in the public arena, ECT is considered to be controversial partly because of misleading portrayals of it in movies," Prof Loo said.

"In the medical fraternity, it is not considered to be controversial as there is very good evidence for it being the most effective proven treatment we have for severe depression."