Posttraumatic stress disorder[1][2] (
PTSD) is an
anxiety disorder that can develop after exposure to one or more terrifying events that threatened or caused grave physical harm. It is a severe and ongoing emotional reaction to an extreme
psychological trauma.
[3] This stressor may involve someone's actual death, a threat to the patient's or someone else's life, serious physical injury, or threat to physical or psychological integrity, overwhelming
psychological defenses. In some cases it can also be from profound psychological and emotional trauma, apart from any actual physical harm. Often, however, the two are combined. PTSD is a condition distinct from
traumatic stress, which has less intensity and duration, and
combat stress reaction, which is transitory. PTSD has also been recognized in the past as
railway spine,
shell shock,
traumatic war neurosis, or
post-traumatic stress syndrome (
PTSS).
PTSD is believed to be caused by psychological trauma.[1] Possible sources of trauma includes encountering or witnessing childhood or adult physical, emotional or sexual abuse.[1] In addition, encountering or witnessing an event perceived as life-threatening such as physical assault, adult experiences of sexual assault, accidents, drug addiction, illnesses, medical complications, or the experience of, or employment in occupations exposed to war (such as soldiers) or disaster (such as emergency service workers). Traumatic events that may cause PTSD symptoms to develop include violent assault, kidnapping, torture, being a hostage, prisoner of war or concentration camp victim, experiencing a disaster, violent automobile accidents or getting a diagnosis of a life-threatening illness.[1] Children may develop PTSD symptoms by experiencing sexually traumatic events like age-inappropriate sexual experiences.[1] Witnessing traumatic experiences or learning about these experiences may also cause the development of PTSD symptoms.[1] The amount of dissociation that follows directly after a trauma predicts PTSD individuals who are more likely to dissociate during a traumatic event are considerably more likely to develop chronic PTSD.[4] Members of the Marines and Army are much more likely to develop PTSD than Air Force and Navy personnel, because of greater exposure to combat.[1] A preliminary study found that mutations in a stress-related gene interact with child abuse to increase the risk of PTSD in adults.[5][6][7]
PTSD displays biochemical changes in the brain and body that differ from other psychiatric disorders such as major depression. Individuals diagnosed with PTSD respond more strongly to a dexamethasone suppression test than individuals diagnosed with clinical depression.[citation needed] In addition, most PTSD also show a low secretion of cortisol and high secretion of catecholamine in urine, with a norepinephrine/cortisol ratio consequently higher than comparable non-diagnosed individuals.[8] This is in contrast to the normative fight-or-flight response, in which both catecholamine and cortisol levels are elevated after exposure to a stressor.[citation needed] Brain catecholamine levels are low,[citation needed] and corticotropin-releasing factor (CRF) concentrations are high.[9][10] 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.[11] 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.[citation needed] 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.[12]
Low cortisol levels may predispose individuals to PTSD; following war trauma, Swedish soldiers serving in Bosnia and Herzegovina with low pre-service salivary cortisol levels had a higher risk of reacting with PTSD symptoms, following war trauma, than soldiers with normal pre-service levels.[13] 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. However, 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.[14]
