The term comorbidity refers to co-occurring psychological diagnoses. Posttraumatic stress disorder (PTSD) certainly can exist in the absence of any other psychological syndromes. However, it is very common for people meeting diagnostic criteria for PTSD to simultaneously manifest one or more other diagnoses. Where PTSD is accompanied by other diagnoses, their detection is essential in the development of an appropriate treatment plan. Such a plan can either be primarily behavioral health treatment approaches that are evidence-based or based on a theory that is evidence-based if no treatment exists.

According to the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR), PTSD comorbidity includes co-occurring anxiety in the form of a specific phobia (diagnostic code 300.29), agoraphobia (300.22), or panic disorder ...