Acute Stress Disorder

Acute Stress Disorder (Also Known As Mental Shock)

Acute stress disorder (ASD) – also known as acute stress reaction, psychological shock, mental shock or simply shock – is a psychological response to a terrifying, traumatic or surprising experience. Acute stress disorder is not fatal, but it may bring about delayed stress reactions (better known as Post-Traumatic Stress Disorder or PTSD) if not correctly addressed.

Types of ASD

 Sympathetic (also known as ‘fight or flight’ response)

Sympathetic Acute Stress Disorder is caused by the release of excessive adrenaline and norepinephrine into the nervous system. These hormones may speed up a person’s pulse and respiratory rate, dilate pupils or temporarily mask pain.

This type of ASD developed as an evolutionary advantage to help humans survive dangerous situations. The ‘fight or flight’ response may allow for temporarily-enhanced physical output, even in the face of severe injury. However, other physical illnesses become more difficult to diagnose, as ASD masks the pain and other vital signs that would otherwise be symptomatic.


Parasympathetic Acute Stress Disorder is characterized by feeling faint and nauseous. This response is fairly often triggered by the sight of blood. In this stress response the body releases acetylcholine. In many ways this reaction is the opposite of the sympathetic response, in that it slows the heart rate and can cause the patient to either regurgitate or temporarily lose consciousness. The evolutionary value of this is unclear, although it may have allowed for prey to appear dead to avoid being eaten.

Signs and symptoms

The Acute Stress Disorder must be accompanied by the presence of dissociative symptoms, which largely differentiates it from PTSD.

Dissociative symptoms include

  • a sense of numbing or detachment from emotional reactions,
  • a sense of physical detachment – such as seeing oneself from another perspective, decreased awareness of one’s surroundings, the perception that one’s environment is unreal or dreamlike,
  • and the inability to recall critical aspects of the traumatic event (dissociative amnesia).

In addition to these characteristics, ASD can be present in the following four distinct symptom clusters;

  • Intrusion symptom cluster – (1) Recurring and distressing dreams, flashbacks, and/or memories related to the traumatic event. (2) Intense/prolonged psychological distress or somatic reactions to internal or external traumatic cues.
  • Negative mood cluster – A persistent inability to experience positive emotions such as happiness, loving feelings, or satisfaction.
  • Avoidance symptom cluster – The avoidance of distressing memories, thoughts, feelings (or external reminders of them) that are closely associated with the traumatic event.
  • Arousal symptom cluster – Sleep disturbances, hyper-vigilance, difficulties with concentration, easily startled, and irritability/anger/aggression.


There are several theoretical perspectives on trauma response, including cognitive, biological, and psycho-biological. While PTSD-specific, these theories are still useful in understanding Acute Stress Disorder as the two disorders share many symptoms. A recent study found that even a single stressful event may have long-term consequences on cognitive function. This result calls the traditional distinction between the effects of acute and chronic stress into question.


Symptoms must last for three consecutive days to be classified as Acute Stress Disorder. If symptoms persist past one month, the diagnosis of PTSD is explored. There must be a clear temporal connection between the impact of an exceptional stressor and the onset of symptoms.

Onset is usually within a few minutes or days but may occur up to one month after the stressor. Also, the symptoms show a mixed and rapidly changing picture; although ‘daze’ depression, anxiety, anger, despair, hyper-activity, and withdrawal may all be seen, no one symptom dominates for long.

The symptoms usually resolve rapidly where removal from the stressful environment is possible. In cases where the stress continues, the symptoms usually begin to diminish after 24–48 hours and are usually minimal after about three days.


This disorder may resolve itself with time or may develop into a more severe disorder – such as PTSD. However, results of the Creamer, O’Donnell and Pattison’s (2004) study of 363 patients suggests that a diagnosis of Acute Stress Disorder had only limited predictive validity for PTSD.

Studies have been conducted to assess the efficacy of counselling and psychotherapy for people with Acute Stress Disorder. Cognitive Behavioural Therapy, which includes exposure and cognitive restructuring, was found to be effective in preventing PTSD in patients diagnosed with Acute Stress Disorder.

A combination of relaxation, cognitive restructuring, imaginal exposure was superior to supportive counselling. Mindfulness-based stress reduction programs also appear to be effective for stress management.

If therapy is not available then the treatment for Acute Stress Reaction is very similar to the treatment of cardiogenic shock and vascular shock. That is, allowing the patient to lie down, providing reassurance and removing the stimulus that prompted the reaction. In traditional shock cases, this generally means relieving injury pain or stopping blood loss.

In an acute stress reaction, this may mean pulling a rescuer away from the emergency to calm down or blocking the sight of an injured friend from a patient.



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