然而大多数经历创伤性事件的人在应激的情况下会经历一个简短的急性反应且从不会形成持久的病理反应，一小部分人将患上创伤后应激障碍或同时合并如抑郁症、广泛性焦虑症或药物滥用等共患病。[26]Neria Y, Gross R, Olfson M, et al. Posttraumatic stress disorder in primary care one year after the 9/11 attacks. Gen Hosp Psychiatry. 2006;28:213-222.http://www.ncbi.nlm.nih.gov/pubmed/16675364?tool=bestpractice.com[29]Kessler RC, Sonnega A, Bromet E, et al. Posttraumatic stress disorder in the National Comorbidity Survey. Arch Gen Psychiatry. 1995;52:1048-1060.http://www.ncbi.nlm.nih.gov/pubmed/7492257?tool=bestpractice.com[106]Shalev AY, Freedman S, Peri T, et al. Prospective study of posttraumatic stress disorder and depression following trauma. Am J Psychiatry. 1998;155:630-637.http://www.ncbi.nlm.nih.gov/pubmed/9585714?tool=bestpractice.com
受危险因素和保护因素的影响，可以由急性病程转变为长期慢性病程。例如，获得治疗，社会支持，有效的应对策略可能对其康复产生影响。暴露和生命财产损失的严重程度可能与漫长而复杂的疾病过程相关联。[107]Galea S, Ahern J, Resnick H, et al. Psychological sequelae of the September 11 terrorist attacks in New York City. N Engl J Med. 2002;346:982-987.http://www.nejm.org/doi/full/10.1056/NEJMsa013404#t=articlehttp://www.ncbi.nlm.nih.gov/pubmed/11919308?tool=bestpractice.com
症状的平均持续时间，如果经过治疗是 36 个月，若未经治疗则症状的平均持续时间为 64 个月。此外，虽然有近 50％的患者症状会显著缓解，仍有三分之一以上从未完全缓解。[29]Kessler RC, Sonnega A, Bromet E, et al. Posttraumatic stress disorder in the National Comorbidity Survey. Arch Gen Psychiatry. 1995;52:1048-1060.http://www.ncbi.nlm.nih.gov/pubmed/7492257?tool=bestpractice.com
