Scientists said Thursday they had, for the first time, helped women with severe anorexia through electrodes implanted into their brains.

The technique is in an experimental phase and only some patients had improved, but the treatment showed promise, they wrote in the Lancet medical journal.

After nine months, three of the six patients in the trial had put on weight and appeared to be in a better state of mind, said the team of specialists from the United States and Canada.

For the three, "this was the longest period of sustained increase in BMI (Body Mass Index -- the ratio between a person's height and weight) since the onset of their illness," wrote the authors.

Furthermore, the technique known as deep brain stimulation (DBS) "was associated with improvements in mood, anxiety... and anorexia nervosa-related obsessions and compulsions in four patients and with improvements in quality of life in three patients after six months of stimulation," said the paper.

Three patients, however, showed no weight improvement and the scientists pointed out that the procedure was associated with "several adverse events" -- including one woman suffering a seizure.

Other effects included panic attacks, nausea and pain.

Anorexia nervosa is usually a chronic illness that affects nearly one percent of people. It is typically diagnosed in young women aged 15-19.

It has one of the highest mortality rates of a psychiatric disorder -- between six and 11 percent -- and is among the most difficult to treat, the authors wrote.

The trial involved implanting electrodes into the part of the brain that regulates emotion so as to moderate the activity of dysfunctional brain circuits.

The device, which works similar to a pacemaker, was connected to a pulse generator implanted under the skin.

A the time of surgery, the women were aged between 24 and 57 and had been suffering from anorexia for between four and 37 years.

DBS is used to treat several neurological disorders including Parkinson's disease and chronic pain, but this was a first for anorexia.

In a comment on the study, Janet Treasure and Ulrike Schmidt of King's College London's Institute of Psychiatry said the findings were "promising".

"The fact that the procedure was associated in some patients with improvements in affective and obsessional symptoms is of key importance since such improvements will go some way towards reassuring patients that DBS is not just another treatment designed to fatten them up without making them feel better," they wrote.