Clin Psychol Rev 32 (2): 122 - 138, 2012. doi: 10.1016 / j. cpr.2011.12.001 Key Points ASD typically begins immediately after the trauma and lasts from 3 days to 1 month; PTSD lasts for > 1 month and can be a continuation of ASD or may manifest up to 6 months after the trauma.