'I've Been Taking Ketamine For My Depression'
Media playback is unsupported on your device
'I've been taking ketamine for my depression'
6 April 2017 Last updated at 07:19 BST
Dr Rupert McShane, who has led a trial in Oxford since 2011, says ketamine can work on patients like Helen who have depression "where nothing has helped before".
He adds there should be a national registry for those who prescribe the treatment to monitor the consequences and avoid mishandle of the Class B substance.
Commenting on the Lancet Psychiatry paper, Prof Allan Young, from the The Royal College of Psychiatrists, said there were still "significant gaps" in knowledge about ketamine's use.