PTSD explained

Post-traumatic stressRelating to injury or concern. disorder (PTSD) is an anxiety disorder that is precipitated by the occurrence of a traumatic event.[1] It is believed that the enormous stressRelating to injury or concern. levels associated with such events can overwhelm normal coping responses.[2]

The symptoms of PTSD significantly disrupt the normal activities of daily living. Symptoms must last for at least six weeks before a diagnosisThe process of determining which condition a patient may have. can be made; those who have symptoms for less than this are diagnosed with 'acuteHas a sudden onset. stressRelating to injury or concern. disorder'.[1]

PTSD may occur at any age. The symptoms vary from person to person, and according to the intensity and duration of the traumatic event, but may include:[1-3]

  • Persistent re-experiencing of the precipitating traumatic event
  • Avoidance of usual activities, particularly those that may trigger memory of the traumatic event
  • Symptoms of increased arousal.

A key differentiating factor between PTSD and a healthy fear response is the failure of the body to return to its pretraumatic state. The 'fight-or-flight' response persists for a long time after the threat has passed.[1,2]

Biologic responses seen with PTSD may include:[1,2]

  • Increased activity of the adrenal glands (two small organs that sit above the kidneys)
  • Altered levels of the stressRelating to injury or concern. hormoneA substance produced by a gland in one part of the body and carried by the blood to the organs or tissues where it has an effect. cortisolA steroid hormone important for helping to regulate carbohydrate metabolism and the stress response.
  • Increased thyroid activity.

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The type of traumatic events that may trigger PTSD

Criteria for PTSD specify that the precipitating traumatic event must be 'outside the range of usual human experience'. However, stressors that are not that uncommon, such as road traffic accidents, can trigger this condition.[4]

Medical conditions can also trigger PTSD, although this is a less common precipitating event than those are more traditionally viewed as traumatic events, for example natural disasters or shootings.[5]

The causes of PTSD

There is no single accepted theory of the underlying cause of PTSD.[4]

One possible explanation is conditioning. Certain stimuli that were present at the time of the trauma, for example sights or sounds, may become associated with the trauma. This leads to the avoidance of these stimuli.[4]

Traumatic events can change a person's view of the world, themselves, and their future. It has been suggested that such an event can 'shatter' previously held beliefs, for example, that the world is a safe place.[4]

Another possible theory of the underlying cause of PTSD is the poor recall of the event. Some have suggested that re-experiencing in PTSD occurs because there is poor memory of the trauma event, and it is not well placed in time and place.[4]

Biological processes make people with PTSD hyper-responsive to stressful stimuli, particularly those that bring about memories of the traumatic event.[4]

People with PTSD may have a chronicA disease of long duration generally involving slow changes. stressRelating to injury or concern. reaction. This leads to persistent elevation of the hormones adrenalineA hormone produced by the adrenal glands, which stimulates increases in the heart rate, breathing and metabolic rate. and noradrenaline, with higher heart rates and bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. pressure, and enhanced startle responses.[4]

Other hormones that may have altered levels in PTSD include cortisolA steroid hormone important for helping to regulate carbohydrate metabolism and the stress response. (reduced levels) and corticotrophin-­releasing factor (increased levels). Increased levels of thyroid hormones have also been noted, which may be correlated with the severity of symptoms of arousal.[4]

Imaging studies have shown a reduced volume of an area of the brain called the hippocampus among veterans. Some believe that this reduction in volume may lead to an enhanced reactivity to stressRelating to injury or concern., and possibly memory deficits as well.[4]

Finally, some studies involving twins have found that identical twins ('monozygotic twins') are more likely to both experience PTSD after experiencing similar stressors than non-identical ('dizygotic') twins.[4]

The behaviours that can perpetuate the symptoms of PTSD

Certain behaviours can maintain the symptoms of PTSD, preventing recovery. These may include:[5]

  • Avoidance of reminders
  • Suppression of memories of the event
  • Rumination (intent contemplation)
  • Dissociation
  • Use of alcohol or drugs.

These behaviours, for example rumination, are often unintentional.[4]

  1. Last accessed July 14, 2010
  2. Schoenfeld FB, Marmar CR and Neylan TC. Current concepts in pharmacotherapy for posttraumatic stressRelating to injury or concern. disorder. Psychiatric Services 2004; 55: 519-31.
  3. Layton B and Krikorian R. Memory mechanisms in posttraumatic stressRelating to injury or concern. disorder. J Neuropsychiatry Clin Neurosci 2002; 14: 254-61.
  4. Semple D and Smyth R. Oxford Handbook of Psychiatry 2009; 2nd Edition.
  5. Budur K, Falcone T and Franco K. Diagnosing and managing posttraumatic stressRelating to injury or concern. disorder. Cleveland Clinic Journal of Medicine 2006; 73: 121-9.