The effect of attempted thought suppression in acute stress disorder.

Attempted suppression of traumatic memories was investigated in survivors of motor vehicle accidents with acute stress disorder (ASD; n = 24) and without ASD (n = 24). Participants monitored their trauma-related thoughts for three 5-minute periods. In Period 1, participants were instructed to think about anything. For Period 2, participants were administered suppression or non-suppression instructions relating to thoughts of the trauma. In Period 3, participants were again instructed to think about anything. ASD participants reported higher ratings of anxiety, frequency of trauma-related thoughts, and attempted suppression of trauma-related thoughts than non-ASD participants. Participants who were given suppression instructions demonstrated a delayed increase in trauma-related thoughts in the period subsequent to suppression.