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In PTSD patients, the dexamethasone cortisol suppression is strong, while it is weak in patients with major depression. In most PTSD patients the urine secretion of cortisol is low, at the same time as the catecholamine secretion is high, and the norepinephrine/cortisol ratio is increased. Brain catecholamine levels are low, and corticotropin-releasing factor (CRF) concentrations are high. There is also an increased sensitivity of the Hypothalamic-pituitary-adrenal axis (HPA axis), with a strong negative feedback of cortisol, due to a generally increased sensitivity of cortisol receptors (Yehuda, 2001).
The response to stress in PTSD is abnormal with long-term high levels of norepinephrine, at the same time as cortisol levels are low, a pattern associated with facilitated learning in animals. Translating this reaction to human conditions gives a pathophysiological explanation for PTSD by a maladaptive learning pathway to fear response (Yehuda 2002). With this deduction follows that the clinical picture of hyperreactivity and hyperresponsiveness in PTSD is consistent with the sensitive HPA-axis.
Swedish United Nations soldiers serving in Bosnia 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 (Aardal-Eriksson 2001).
Another possible factor in PTSD is that a persistence of depressive symptoms may be caused by an underlying biochemical disorder, associated with insulin resistance (dysglycemia), that can be treated by a hypoglycemic diet.