Why are we still using electroconvulsive therapy?

The idea of treating a psychiatric illness by passing a jolt of electricity through the brain was one of the most controversial in 20th Century medicine.

It started out as an experiment in the 1930s after psychiatrists noticed some heavily distressed patients would suddenly improve after an epileptic fit. Passing a strong electric current through the brain could trigger a similar seizure and - they hoped - a similar response.

By the 1960s it was being widely used to treat a variety of conditions, notably severe depression. But as the old mental asylums closed down and aggressive physical interventions like lobotomies fell out of favour, so too did electroshock treatment, as ECT was previously known.

But for a group of the most severely depressed patients, ECT has remained one of the last options on the table when other therapies have failed. Annually in the UK around 4,000 patients still undergo ECT, as Jim Reed reports for BBC Newsnight.