Ketamine could help people with severe depression
Scientists at Oxford University have found that the drug Ketamine can cure severe depression even in people who have stopped responding to other anti-depressants.

Horse tranquilliser Ketamine can cure people who have battled severe depression for 20 years, researchers at Oxford University have found.

Sufferers who had failed to respond to anti-depressants like Prozac reported 'feeling themselves again' after decades of misery, just days after intravenous infusions of the class 2 drug.

And relatives told doctors it was like having the sufferer 'back again.'

During the study, 38 patients with severe depression were treated over three weeks. 30 per cent saw their depressive symptoms lessen by 50 per cent while one in eight had complete remission.

"We've seen remarkable changes in people who have had severe depression for many years that no other treatment has touched," said Dr Rupert McShane, a consultant psychiatrist at Oxford Health researcher at Oxford University's Department of Psychiatry.

"It's very moving to witness. Patients often comment that the flow of their thinking seems suddenly freer.

"For some, ever a brief experience of response helps them to realise that they can get better and this gives hope.

"They very often say, 'this is how I used to think. I recognise it.' It's the sort of thing that really makes it worth doing psychiatry. It's a really wonderful thing to see."

Ketamine is a licensed drug which is already used widely in the NHS as an anaesthetic and in pain relief. However it is not currently cleared to be used as an anti-depressant.

It is a banned class B substance, but the doses used in the new treatment are far less than those used on the street. Drug addicts take several grams a day which can lead to severe bladder problems and brain damage. The dose used in the study was just 80mg.

The drug works by 'turning down' an area of the brain called the 'anterior cingulate' which is responsible for feelings of self, guilt and worthlessness. In people suffering from depression this area has been shown to be over-active. Ketamine restricts blood flow to the area, and dampens the effect.

Although some trial subjects reported side-effects following the infusions, they appeared to disappear after five hours.

Those taking part in the study were so depressed that the next option available was electroconvulsive therapy (ECT) because other drugs had failed to work. However ECT is known to cause memory loss and is normally used as a last resort.

In one woman, just one treatment prevented any relapse for nine months. However most needed several infusions to stay in remission.

Dr McShane added: "We now need to build on clinical experience with Ketamine in a small number of carefully monitored patients.

"By trying different infusion regimes and adding other licensed drugs, we hope to find simple ways to prolong its dramatic effect."

The study was published in the Journal of Psychopharmacology.