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BackgroundAlthough numerous studies have investigated the neurobiology and neuroendocrinology of posttraumatic stress disorder (PTSD) after single finished trauma, studies on PTSD under ongoing threat are scarce and it is still unclear whether these individuals present similar abnormalities.ObjectiveThe purpose of this review is to present the neurobiological and neuroendocrine findings on PTSD under ongoing threat. Ongoing threat considerably affects PTSD severity and treatment response and thus disentangling its neurobiological and neuroendocrine differences from PTSD after finished trauma could provide useful information for treatment.MethodEighteen studies that examined brain functioning and cortisol levels in relation to PTSD in individuals exposed to intimate partner violence, police officers, and fire fighters were included.ResultsHippocampal volume was decreased in PTSD under ongoing threat, although not consistently associated with symptom severity. The neuroimaging studies revealed that PTSD under ongoing threat was not characterized by reduced volume of amygdala or parahippocampal gyrus. The neurocircuitry model of PTSD after finished trauma with hyperactivation of amygdala and hypoactivation of prefrontal cortex and hippocampus was also confirmed in PTSD under ongoing threat. The neuroendocrine findings were inconsistent, revealing increased, decreased, or no association between cortisol levels and PTSD under ongoing threat.ConclusionsAlthough PTSD under ongoing threat is characterized by abnormal neurocircuitry patterns similar to those previously found in PTSD after finished trauma, this is less so for other neurobiological and in particular neuroendocrine findings. Direct comparisons between samples with ongoing versus finished trauma are needed in future research to draw more solid conclusions before administering cortisol to patients with PTSD under ongoing threat who may already exhibit increased endogenous cortisol levels.Highlights of the articleWe reviewed the neurobiological and neuroendocrine findings in PTSD under ongoing threat.PTSD under ongoing threat demonstrated similar brain abnormalities as PTSD after finished trauma.Several studies found increased cortisol levels in PTSD under ongoing threat.Hydrocortisone administration might not be beneficial for individuals with PTSD under ongoing threat with elevated endogenous cortisol levels.Direct comparisons between ongoing versus finished trauma are needed to provide robust conclusions and clinical recommendations.

Besides fight and flight responses, animals and humans may respond to threat with freezing, a response characterized by bradycardia and physical immobility. Risk assessment is proposed to be enhanced during freezing to promote optimal decision making. Indeed, healthy participants showed freezing-like responses to threat cues. Posttraumatic stress disorder (PTSD) patients are characterized by hypervigilance and increased threat responsiveness. We propose that threat responses will be characterized by decreased freezing in PTSD, eliminating possibilities for rejecting cognitive distortions, such as harm expectancy, and thereby contributing to the maintenance of the disorder. However, freezing responses have hardly been investigated in PTSD. Using a stabilometric platform to assess body sway as an indicator of freezing-like behavior, we examined whether veterans with PTSD would show diminished freezing responses to unpleasant versus neutral and pleasant pictures. Fourteen PTSD patients and 14 healthy matched controls watched the pictures, while body sway and heart rate (HR) were continuously assessed. Replicating previous findings, healthy controls showed decreased body sway and HR in response to unpleasant pictures, indicative of freezing-like behavior. In contrast, this response pattern was not observed in PTSD patients. The results may indicate a reduced freezing response in PTSD. As reduced freezing may hinder appropriate risk assessment, it may be an important factor in the maintenance of PTSD. Future research might clarify whether impaired freezing is a PTSD-specific or a transdiagnostic symptom, being present in threat-related disorders.

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Background: Tonic immobility (TI) is a state of physical immobility associated with extreme stress and the development of posttraumatic stress disorder (PTSD). However, it is unknown whether TI is associated with a distinct actual stress response, i.e., objective immobility measured by a stabilometric platform. This study made a first step in exploring this as well as differences in body sway responses between PTSD patients and healthy controls. We hypothesized that PTSD would be related to increased body sway under stress, whereas TI would be related to decreased body sway under stress.Methods: Eye closure was selected as a PTSD-relevant stress induction procedure.Body sway and heart rate (HR) were measured in 12 PTSD patients and 12 healthy controls in four conditions: (1) maintaining a stable stance with eyes open, (2) with eyes closed, (3) during a mental arithmetic task with eyes open, and (4) with eyes closed. Results: As predicted, PTSD patients showed increased body sway from eyes open toeyes closed compared to controls and this effect was eliminated by executing the arithmetic task. Most importantly, retrospective self-reported TI was associated with lower body sway increases in PTSD and higher body sway decreases in controls from eyes-open to eyes-closed conditions. Conclusions:These preliminary findings suggest that eye closure has a different effect on PTSD patients than controls and that high self-reported TI might indicate a distinct stress response pattern, i.e., a proneness for immobility. It may be relevant to take such individual differences in stress-response into account in PTSD treatment. K E Y W O R D Sbehavioral activation, life events, PTSD, stress, trauma