Acute stress reaction (ASR), also known as psychological shock, mental shock, or simply shock, as well as acute stress disorder (ASD), is a psychological response to a terrifying, traumatic, or surprising experience. The reactions may include but are not limited to intrusive thoughts, or dissociation, and reactivity symptoms such as avoidance or hyperarousal. It may be exhibited for days or weeks after the traumatic event. If the condition is not correctly addressed, it may develop into post-traumatic stress disorder (PTSD).
Diagnosis
The International Classification of Diseases (ICD) treats this condition differently from the Diagnostic and Statistical Manual of Mental Disorders (DSM).
According to the ICD-11, acute stress reaction refers to the symptoms experienced a few hours to a few days after exposure to a traumatic event. In contrast, DSM-5 defines acute stress disorder by symptoms experienced 48 hours to one month following the event. Symptoms experienced for longer than one month are consistent with a diagnosis of PTSD per both classifications.
ICD-11 criteria
The ICD-11 MMS gives the following description:
DSM-5 criteria
According to the DSM-5, acute stress disorder requires the exposure to actual or threatened death, serious injury, or sexual violation by either directly experiencing it, witnessing it in person, learning it occurred to a close family or friend, or experiencing repeated exposure to aversive details of a traumatic event. In addition to the initial exposure, individuals may also present with a variety of different symptoms that fall within several clusters including intrusion, negative mood, dissociation, avoidance of distressing memories and emotional arousal. Intrusion symptoms include recurring and distressing dreams, flashbacks, or memories related to the traumatic event and related somatic symptoms. Emotional arousal symptoms include sleep disturbances, hypervigilance, difficulties with concentration, more common startle response, and irritability.
The sympathetic branch of the autonomic nervous system gives rise to a specific set of physiological responses to physical or psychological stress. The body's response to stress is also termed a "fight or flight" response, and it is characterised by an increase in blood flow to the skeletal muscles, heart, and brain, a rise in heart rate and blood pressure, dilation of pupils, and an increase in the amount of glucose released by the liver.
The onset of an acute stress response is associated with specific physiological actions in the sympathetic nervous system, both directly and indirectly through the release of adrenaline and, to a lesser extent, noradrenaline from the medulla of the adrenal glands. These catecholamine hormones facilitate immediate physical reactions by triggering increases in heart rate and breathing, constricting blood vessels. An abundance of catecholamines at neuroreceptor sites facilitates reliance on spontaneous or intuitive behaviours often related to combat or escape.
Normally, when a person is in a serene, non-stimulated state, the firing of neurons in the locus ceruleus is minimal. A novel stimulus, once perceived, is relayed from the sensory cortex of the brain through the thalamus to the brain stem. That route of signalling increases the rate of noradrenergic activity in the locus ceruleus, and the person becomes more alert and attentive to their environment.
If a stimulus is perceived as a threat, a more intense and prolonged discharge of the locus ceruleus activates the sympathetic division of the autonomic nervous system. The activation of the sympathetic nervous system leads to the release of norepinephrine from nerve endings acting on the heart, blood vessels, respiratory centers, and other sites. The ensuing physiological changes constitute a major part of the acute stress response. The other major player in the acute stress response is the hypothalamic-pituitary-adrenal axis. Stress activates this axis and produces neuro-biological changes. These chemical changes increase the chances of survival by bringing the physiological system back to homeostasis.
The autonomic nervous system controls all automatic functions in the body and contains two subsections within it that aid the response to an acute stress reaction. These two subunits are the sympathetic nervous system and the parasympathetic nervous system. The sympathetic response is colloquially known as the "fight-or-flight response," indicated by accelerated pulse and respiration rates, pupil dilation, and a general feeling of anxiety and hyper-awareness. This is caused by the release of epinephrine and norepinephrine from the adrenal glands. The epinephrine and norepinephrine strike the beta receptors of the heart, which feeds the heart's sympathetic nerve fibres to increase the strength of heart muscle contraction; as a result, more blood gets circulated, increasing the heart rate and respiratory rate. The sympathetic nervous system also stimulates the skeletal system and muscular system to pump more blood to those areas to handle the acute stress. Simultaneously, the sympathetic nervous system inhibits the digestive system and the urinary system to optimize blood flow to the heart, lungs, and skeletal muscles. This plays a role in the alarm reaction stage. The parasympathetic response is colloquially known as the "rest and digest" response, indicated by reduced heart and respiration rates, and, more obviously, by a temporary loss of consciousness if the system is fired at a rapid rate. The parasympathetic nervous system stimulates the digestive system and urinary system to send more blood to those systems to increase the process of digestion. To do this, it must inhibit the cardiovascular system and respiratory system to optimise blood flow to the digestive tract, causing low heart and respiratory rates. The parasympathetic nervous system plays no role in acute stress response.
Studies have shown that patients with acute stress disorder have overactive right amygdalae and prefrontal cortices; both structures are involved in the fear-processing pathway. Early pharmacotherapy may prevent the development of post-traumatic symptoms. Additionally, early trauma-focused cognitive behavioural therapy (TF-CBT) for those with a diagnosis of ASD can protect an individual from developing chronic 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 with clinically significant results at six-month follow-up appointments. A combination of relaxation, cognitive restructuring, imaginal exposure, and in-vivo exposure was superior to supportive counselling. Mindfulness-based stress reduction programmes also appear to be effective for stress management.
The pharmacological approach has made some progress in lessening the effects of acute stress disorder. To relax patients and allow for better sleep, prazosin can be given to patients, which regulates their sympathetic response. Hydrocortisone has shown some success as an early preventative measure following a traumatic event, typically in the treatment of PTSD.
In a context where counseling, psychotherapy, and cognitive behavioral therapy is unlikely to be available, the treatment for acute stress reaction 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.
Since its addition to the DSM-IV, questions about the efficacy and purpose of the ASD diagnosis have been raised. The diagnosis of ASD was criticized as an unnecessary addition to the progress of diagnosing PTSD, as some considered it more akin to a sign of PTSD than an independent issue requiring diagnosis. Also, the terms ASD and ASR have been criticized for not fully covering the range of stress reactions.