The percentage of cases in which PTSD "co-occurs with mood, anxiety, or substance-use disorders," according to a statistic cited in a recent review article in the New England Journal of Medicine -- Post-Traumatic Stress Disorder. This relatively short but comprehensive article is well worth a look.
Abstract: Reports of violence, injury, and death appear daily on headline news. More than 70% of adults worldwide experience a traumatic event at some time in their lives, and 31% experience four or more events. Post-traumatic stress disorder (PTSD) is the most prevalent psychopathological consequence of exposure to traumatic events. The lifetime prevalence of PTSD varies according to social background and country of residence, ranging from 1.3 to 12.2%, and the 1-year prevalence is 0.2 to 3.8%. The core features of PTSD are the persistence of intense, distressing, and fearfully avoided reactions to reminders of the triggering event, alteration of mood and cognition, a pervasive sense of imminent threat, disturbed sleep, and hypervigilance. This report outlines our current understanding of the diagnosis, prevalence, neurobiologic characteristics, and treatment of PTSD, as well as the clinical implications of this knowledge.