Between 1969 and 2001, 3524 people were killed in civil disturbances in Northern Ireland. The annual death rate peaked at 479 in a population of 1.6 million. Deaths and injuries were unequally distributed, with people in working class urban communities and those living close to the Irish border being most at risk. Lessons can be learnt from such conflict, not only about the management of single episodes of psychological trauma but also about the effects of long term, violent divisions in society on mental health.

One of the aims of terrorism is to change attitudes and behaviours. This can lead to mental health problems in people who are targeted and in others. Problems include post-traumatic stress disorder, anxiety, depression, substance misuse, and (rarely) precipitation of psychosis. Post-traumatic stress disorder can be treated by psychological treatments such as trauma focused cognitive behaviour therapy1 or antidepressants.2 In this week's BMJ, a randomised controlled trial by Duffy and colleagues assesses the effectiveness of cognitive behaviour therapy in 58 people with chronic post-traumatic stress disorder …