Competing interests: The BMJ has judged that there are no disqualifying financial ties to commercial companies. The author declares the following other interests: Awards of grant funding to support research from various sources to conduct research in the field of traumatic stress, including the National Institute for Health Research, Forces in Mind Trust and Medical Association for Psychedelic Studies; and development of a guided self help intervention owned by Cardiff University for which he could receive a share of royalties in the future.