ptsd Flashcards
what is the definition/ criteria of PTSD
an exposure to a traumatic event that involves actual or threatened death, serious injury or sexual violence through:
directly experiencing the trauma
witnessing the events occur to others
learning that traumatic events occurred to a close family member
experiencing extreme or repeated exposure of trauma to others
give some background on PTSD
occurs due to a traumatic event so severe that it breaks the stress response management
most people exposed to trauma do not develop PTSD
individuals with PTSD have underlying physiological differences that result in a failure to recover, the trauma unmasks the physiology
trauma itself also alters the physiology
some of the underlying physiological difference is genetic and epigenetics play a large role
rate of PTSD increases with intimacy of violence
higher rate for child abuse than natural disasters
what is the usual time course for a trauma response
after trauma most individuals have PTSD symptoms for days to weeks; usual response
up to one month: acute stress disorder
longer than one month: PTSD
most individuals symptoms resolve by 3 months
delayed onset PTSD is rare
PTSD can last months to lifetime
what is PTSD prevalence in american war veterans of iraq and afghan wars?
14-20% out of 2.7 million
what are symptoms required for PTSD
re experiencing the trauma; intrusive memories, flashbacks, nightmares, reacting to cues
avoidance and numbing; avoided thoughts, reminders, diminished interest in activities
negative cognitions and mood associated with the trauma
hyperarousal; hypervigilance, irritability, insomnia, startle, poor concentration
pathophysiology: increased heart rate and skin conductance in response to trauma related cues
low basal cortisol levels, raised catecholamine levels
how is fear conditioning associated w ptsd
fear conditioning is a behavioural paradigm in which organisms learn to predict aversive events; such as pavlovian conditioning, long after the precipitating traumatic event environmental cues will continue to serve as triggers for a similar physiologic response
just speaking about event can be trigger; may lead to avoidance of therapy
fear conditioning is adaptive to a dangerous environment; it is essential for survival, however the same behaviour is maladaptive when returned to safety, PTSD is the failure to unlearn adaptive thoughts and behaviours on the return to safety
what brain areas are involved in PTSD
amygdala, hypothalamus, hippocampus, brainstem etc
what neurotransmitters are involved in ptsd
CRH: wide circuit throughout brain
catecholamines: higher NA, flood of NA after traumatic event is key in encoding traumatic memories
serotonin, GABA, glutamate, NPY, endogenous opioids
describe some circuitry involved in ptsd in amygdala
in the amygdala: the basal nucleus of amygdala transmits to central nucleus of amygdala (NA flood), which transmits to VTA via DA pathways, raphe nuclei via 5HT , locus coeruleus via NA pathways
amygdala activity is exaggerated in individuals with ptsd, and is positively correlated with symptom severity
what structures other than the amygdala are altered in ptsd
the insular and dorsal anterior cingulate cortex are also hyper active in ptsd, these structures may modulate the amygdalas expression of fear
the ventromedial prefrontal cortex which also modulates (in this case reduces) the amygdalas expression of fear is diminished in ptsd
there are both hypo and hyper reactivity observed in hippocampus
compare mild stress to extreme stress in the prefrontal cortex
in mild stress the PFC inhibits the amygdala, there are optimum na, da and 5ht levels and there is increased alpha 1/2 activation
in extreme stress the amygdala dominates and there is increased alpha 1/2 activation and excessive DA1R and 5HT2R activation
activation in pfc is mediated by the amygdala through the VTA, raphe nuclei and locus coeruleus
what is the HPA axis
the hypothalamic-pituitary-adrenal axis; body’s fundemental stress response, hypothalamus releases cortocotropin releasing hormone, the anterior pituitar releases adrenocorticotropin causing the adrenal cortex to release cortisol, is the bodys fundemental stress response, people with higher levels of glucocorticoid receptor (for cortisol) are better at detecting cortisol and so recover from stress more quickly
how does cortisol change in ptsd
cortisol is lower in combat veterans than controls
hypothalamic corticotropin releasing hormone release increased in combat veterans
increased negative feedback inhibitions of HPA axis
overall reduced glucocorticoid signalling and exaggerated negative feedback
cortisol alterations in ptsd reflect pre existing conditions; genetic variants in genes NR3C1 and FKBP5 are key
describe memory reconsolidation in ptsd
every time a memory is recalled it is momentarily made labile and then needs to be reconsolidated, during this process the memory may be updated or changed based on new experience; can occur alone or within context of therapy, may lead to fear extinction (better) or memory made worse
what are risk factors for ptsd
severity and nature of trauma
history of childhood adversity/trauma
history of poor coping
low social support
family history of trauma (genetics?)
low heart rate variability, low cortisol, other physiologic variables
