The Adults with Incapacity Act will soon make it possible for the Court of Session to decide whether psychosurgery should be performed.

Psychosurgery is used to treat a very small number of depressed patients when everything else has failed.

A thermal probe is inserted into the brain to destroy a small area.

Treatment will only be approved where it is judged to safeguard or promote the mental health of the adult and the adult does not oppose or resist the treatment

Scottish Executive spokesman

If it works, a patient's personality is changed, but if it is unsuccessful it can result in severe side effects as well as the original condition.

The Scottish Association for Mental Health (SAMH) is extremely concerned that it will soon be possible to carry out this operation without a patient's permission.

Richard Norris, of SAMH, said he was "very surprised" that the Scottish Executive was proceeding with the regulations.

He said that the United Nations General Assembly had passed a resolution specifically prohibiting this sort of operation being given without consent.

Safeguards

But the executive said the operation would only be used for patients whose depression is so severe they cannot decide what is in their best interests.

It pointed out that under the new regulations cases would go before the Mental Welfare Commission and then the Court of Session, before they could go ahead.

An executive spokesman said: "Substantial safeguards are required before treatment can be carried out.

"Treatment will only be approved where it is judged to safeguard or promote the mental health of the adult and the adult does not oppose or resist the treatment."

The Mental Welfare Commission said the law could help patients who are so depressed they cannot make a rational decision.

The Scottish singing star Lena Zavaroni is perhaps the best-known patient of psychosurgery.

She died shortly after receiving the operation to treat her depression and anorexia.