The diagnosis of Post-Traumatic Stress Disorder

Great post outlining the diagnosis of Post-Traumatic Stress Disorder and the application of James and Gilliland's Six-Step Crisis model. Within your post you discussed that, "The diagnosis is defined as a condition that is influenced by terrifying events by experiencing, sustaining, enduring, or witnessing." What are additional presenting symptoms and how does a professional arrive at a differential diagnosis of PTSD versus Acute Stress Disorder (ASD) or other and Unspecified Trauma- and Stressor-Related Disorders?