One-off debriefing sessions after traumatic events are ineffective - and could actually do more harm than good, researchers say.

After traumatic events such as the September 11 attacks, many people take up the offer of a debriefing session - which experts stress is different to long-term counselling.

Researchers analysed studies on the effect of a single session of debriefing within a month of an event.

They found it made no difference to whether people went on to suffer from post-traumatic stress disorder or other psychological problems.

Promising approaches are emerging

Richard Gist, Missouri Fire Department/Grant Devilly, University of Melbourne

Seven studies were looked at by researchers from the University of Amsterdam in the Netherlands.

They covered critical incident stress debriefing (CISD), usually a one-off three-hour, group therapy session for trauma victims.

Others looked at different methods of debriefing and how people fared who had no counselling.

Satisfaction

It was found that symptoms of post-traumatic stress disorder improved with non-CISD interventions and with no intervention at all.

However CISD did not have any such positive effect.

There was also no evidence it improved recovery from other trauma-related disorders.

Researchers led by Arnold van Emmerik, of the Department of Clinical Psychology at the University of Amsterdam, said there were three possible reasons CISD did not seem to help.

They said it could be because it interfered with the natural way people react after a traumatic event, perhaps meaning they bypass support from friends and family.

They suggest it may also be because people continue to be exposed to the factors which traumatised them in the first place.

A third explanation could be that if CISD is offered to those who are not at risk as trauma as well as those who are, it could obscure any beneficial effect of the technique.

But the researchers, writing in The Lancet, say the decision to provide debriefing sessions was not solely based on scientific evidence.

"Reports of satisfaction or perceived helpfulness by participants might be sufficient reasons to continue to offer debriefing."

But they said claims that one-off debriefing sessions could prevent the development of chronic psychological problems are unproven.

Professional

In an editorial in the journal, Richard Gist from Missouri Fire Department and the University of Missouri, Kansas City, USA, and Grant Devilly from the University of Melbourne, Australia, said there was some evidence post-trauma debriefing could help.

"Promising approaches are emerging, with high sensitivity and specificity, allowing straightforward and relatively non-intrusive assessment to identify those at greatest risk of clinical progression to post-traumatic stress disorder.

"These approaches are designed for implementation 2-4 weeks post-impact, when brief-series cognitive behavioural therapy has efficacy in treating post-traumatic stress disorder in high-risk populations."

Phillip Hodson, a fellow of the British Association of Counselling and Psychotherapy, told BBC News Online debriefing could work if it was done properly by trained professionals.

"A lot of CISD is done by well-meaning people, but they are not necessarily the ideal people to carry that out.

"It's not enough to say 'are you feeling OK', a lot of CISD is of that sort of quality."