To be diagnosed with PTSD, using the DSM-5 (2013), a person has to experience or be a witness to a traumatic event, or be aware of violent or accidental death or threatened death of a close friend or family member. It can also relate to experiencing repeated or contact with repelling details of a traumatic event such in the case of first responders, or police officers.

There also needs to be one of more of the following intrusive symptoms, beginning after the traumatic event:

• Repeated, involuntary and intrusive upsetting memories of the trauma
• Repeated frightening dreams related to the traumatic event
• Dissociative responses such as flashback, where the person feels, or behaves as if they are back in the traumatic situation
• Significant distress when exposed to any reminder of the traumatic event
• Continued avoidance of things associated with the traumatic event. This might be avoiding memories related to the event, or of specific places and people. This is in an attempt to avoid distressing emotions.

It is estimated that 800,000 to 1 million Australians will experience PTSD in a 12 month period, and 12% will experience PTSD in their lifetime.

• Psychological treatment of PTSD targets confronting the traumatic memory, via the thoughts and beliefs that have developed around it. Trauma-focused therapy has been found to reduce symptoms including depression that can also occur with PTSD.
• Medication might be used if symptoms are severe.