Psychological therapies for chronic post‐traumatic stress disorder (PTSD) in adults Background: Post‐traumatic stress disorder (PTSD) can occur following a traumatic event. It is characterised by symptoms of re‐experiencing the trauma (in the form of nightmares, flashbacks and distressing thoughts), avoiding reminders of the traumatic event, negative alterations in thoughts and mood, and symptoms of hyper‐arousal (feeling on edge, being easily startled, feeling angry, having difficulties sleeping, and problems concentrating).