This chapter focuses on the diagnosis and assessment of PTSD beginning with the accepted diagnostic criteria for PTSD (Box 2.1) as described in the American Psychiatric Association’s DSM-IV (APA 2000). The chapter presents additional information that might be useful for a comprehensive assessment of a PTSD patient, such as determining comorbidity, symptom severity, functional status, and neuropsychologic impairments. The chapter concludes with a comment about biomarkers that might be of future use in the diagnosis of PTSD.

Although there is a long history of descriptions of posttraumatic syndromes, the modern era of diagnosing PTSD began in 1980 with the introduction of PTSD in the third edition of APA DSM (DSM-III). Formal recognition of PTSD led to a large body of systematic research on its features and research findings led to modification and refinement of the diagnostic criteria. But many of the diagnostic criteria in DMS-III are largely unchanged in the latest edition of the diagnostic manual, DSM-IV.

The evidence-based diagnosis of PTSD, according to DSM-IV (see Box 2.1) has several components: exposure to a traumatic event, intrusive re-experiencing of the event, avoidance and numbing, hyperarousal, at least a month of symptoms, and clinically significant distress or impairment that was not present before the trauma.

The World Health Organization disease classification system, the 10th edition of International Classification of Diseases (ICD-10), also includes diagnostic criteria for PTSD. The ICD diagnostic criteria for PTSD are similar to those in DSM-IV but do not include the DSM-IV criterion A2, that a response to a traumatic event involves intense fear, helplessness, or horror.