Post-traumatic stress disorder
Post-traumatic stress disorder (PTSD) can occur after any major traumatic event.
To fulfil the Diagnostic and Statistical Manual-IV (DSM-IV) criteria for PTSD:
An individual must have been exposed to a traumatic event
Have at least one re-experiencing, three avoidance, and two hyperarousal phenomena
Have had the symptoms for at least 1 month
The symptoms must cause clinically important distress or reduced day-to-day functioning.
It is labelled as acute for the first 3 months and chronic if it lasts beyond 3 months.
People with subsyndromal PTSD have all the criteria for PTSD except one of the re-experiencing, avoidance, or hyperarousal phenomena.
Acute stress disorder occurs within the first month after a major traumatic event and requires the presence of symptoms for at least 2 days.
It is similar to PTSD, but dissociative symptoms are required to make the diagnosis.
Treatments for PTSD may have similar effects, regardless of the traumatic event that precipitated PTSD.
However, great caution should be applied when generalising from one type of trauma to another.
Major trauma (such as rape)
A history of psychiatric disorders
Acute distress and depression after the trauma
Lack of social support
One large cross-sectional study in the USA found that 1/10 (10%) women and 1/20 (5%) men experience PTSD at some stage in their lives.
The cause of PTSD is unknown, but psychological, genetic, physical, and social factors are involved. PTSD changes the body’s response to stress.
It affects the stress hormones and chemicals that carry information between the nerves (neurotransmitters).
Having been exposed to trauma in the past may increase the risk of PTSD.
Repeated "reliving" of the event, which disturbs day-to-day activity
Flashback episodes, where the event seems to be happening again and again
Recurrent distressing memories of the event
Repeated dreams of the event
Physical reactions to situations that remind you of the traumatic event
Emotional "numbing," or feeling as though you don’t care about anything
Feelings of detachment
Inability to remember important aspects of the trauma
Lack of interest in normal activities
Less expression of moods
Staying away from places, people, or objects that remind you of the event
Sense of having no future
Exaggerated response to things that startle you
Excess awareness (hypervigilance)
Irritability or outbursts of anger
May also feel a sense of guilt about the event (including "survivor guilt"), and the following symptoms, which are typical of anxiety, stress, and tension:
Agitation, or excitability
Feeling your heart beat in your chest (palpitations)
PTSD displays biochemical changes in the brain and body that differ from other psychiatric disorders such as major depression.
In addition, most people with PTSD also show a low secretion of cortisol and high secretion of catecholamines in urine, with a norepinephrine/cortisol ratio consequently higher than comparable non-diagnosed individuals.
Together, these findings suggest abnormality in the hypothalamic-pituitary-adrenal (HPA) axis.
Given the strong cortisol suppression to dexamethasone in PTSD, HPA axis abnormalities are likely predicated on strong negative feedback inhibition of cortisol, itself likely due to an increased sensitivity of glucocorticoid receptors.
Some researchers have associated the response to stress in PTSD with long-term exposure to high levels of norepinephrine and low levels of cortisol, a pattern associated with improved learning in animals
Translating this reaction to human conditions gives a pathophysiological explanation for PTSD by a maladaptive learning pathway to fear response through a hypersensitive, hyperreactive and hyperresponsive HPA axis.
Low cortisol levels may predispose individuals to PTSD
Because cortisol is normally important in restoring homeostasis after the stress response, it is thought that trauma survivors with low cortisol experience a poorly contained—that is, longer and more distressing—response, setting the stage for PTSD.
There is considerable controversy within the medical community regarding the neurobiology of PTSD.
A review of existing studies on this subject showed no clear relationship between cortisol levels and PTSD.
Only a slight majority have found a decrease in cortisol levels while others have found no effect or even an increase.
Three areas of the brain whose function may be altered in PTSD have been identified
In human studies, the amygdala has been shown to be strongly involved in the formation of emotional memories, especially fear-related memories.
The amygdalocentric model of PTSD proposes that it is associated with hyperarousal of the amygdala and insufficient top-down control by the medial prefrontal cortex and the hippocampus particularly during extinction.
Further animal and clinical research into the amygdala and fear conditioning may suggest additional treatments for the condition.
There are no tests that can be done to diagnose PTSD.
The diagnosis is made based on a set of symptoms that continue after extreme trauma.
Stepped collaborative care
One large cross-sectional study in the USA found that over a third of people with previous PTSD continued to satisfy the criteria for PTSD 6 years after initial diagnosis.
However, cross-sectional studies provide weak evidence about prognosis.