The dominant features of posttraumatic stress disorder are emotional numbing (i.e., emotional nonresponsiveness), hyperarousal (e.g., irritability, on constant alert for danger), and reexperiencing of the trauma (e.g., flashbacks, intrusive emotions).

Trauma

A trauma is an intensely stressful event during which a person suffers serious harm or the threat of serious harm or death or witnesses an event during which another person (or persons) is killed, seriously injured, or threatened. 

Thus the essential characteristics of a traumatic event include (but are not restricted to):

• A serious threat to one's life
• A serious threat to one's physical integrity
• A serious threat or possible harm to one's children/spouse/close relative/friends
• Sudden destruction of one's home or community
• Seeing another person who has recently been / is being seriously injured or killed
• Physical violence
• Learning about serious threat / harm to relative / family

Traumatic events are commonly classified as follows:

• Abuse
  • Mental
  • Physical
  • Sexual
  • Verbal (i.e., sexual and/or violent content)
• Catastrophe
  • Harmful and fatal accidents
  • Natural disasters (floods, earthquakes, tornadoes)
  • Terrorism (including hostage taking)
• Violent attack
  • Animal attack
  • Assault
  • Battery and domestic violence
  • Rape
• War, battle, and combat
  • Death
  • Explosion
  • Gunfire

Some classic examples include:

• Concentration camps of Nazi Germany
• Bombing of Hiroshima and Nagasaki
• Vietnam War
• Hyatt Regency Hotel disaster
• Buffalo Creek Catastrophe
• Hills and Coconut Graves fire

Types of PTSD

Depending on the onset and duration of symptoms there are four types of PTSD.

So the essential characteristics of each are:

• Acute PTSD: Early onset, early resolution (both within first 6 months)
• Chronic PTSD: Early onset, prolonged course (lasting more than 6 months - necessitating a re-diagnosis from the acute type.
• Delayed PTSD: Onset of symptoms after first 6 months of the traumatic incident.
• Delayed and Chronic PTSD: Although not delineated in DSM III and IV, this is another logical subtype in which the patient has delayed onset of symptoms (6 months after the traumatic event) and has already manifested PTSD symptoms for a period of greater than 6 months prior to daignosis.

Incidence and Prevalence

Kessler et al estimated that the lifetime prevalence of PTSD is 7.8 %. Women had a higher prevalence than men ( 10.4 versus 5.0). This was due to both a greater exposure of high-impact trauma (Rapes, sexual molestation, childhood neglect and childhood physical abuse) and a greater likelihood of developing PTSD when exposed to a traumatic event. 

PTSD is more prevalent among war veterans than among any other group. The National Vietnam Veterans Readjustment Survey reports that approximately 25% of U.S. veterans, men and women, were suffering from PTSD in the early 1990s.
Men with PTSD identify combat and witnessing someone else's injury or death most often as the cause of their condition. Women identify physical attack or threat most often as the cause of their PTSD.

Someone with PTSD is at risk for developing other mental health disorders such as panic disorder, phobias, major depressive disorder, and obsessive-compulsive disorder. Substance use and somatization were also found to be common.

The current epidemiological data stem mainly from studies conducted in United States. As PTSD is commoner in countries where long-term war, widespread social upheaval, and frequent natural disasters are prevalent, namely the developing world, it is possible that the current statistics is a gross understatement of the morbidity caused.

Next: Aetiology - Psychological Processes