40 Post-Traumatic Stress Disorder

What is Post-Traumatic Stress Disorder (PTSD)?

PTSD is an anxiety-like disorder that develops after experiencing or witnessing some form of trauma. It is the only psychiatric disorder with a definitive known cause – traumatic stress. PTSD causes an altered, exaggerate stress response. Those individuals diagnosed with PTSD may feel stressed or frightened even when they are in a safe environment, and they may have triggers that activate their stress response.

Who can get PTSD?

Anyone can be diagnosed with PTSD at any point in their lives. Some of the most common events that lead to a PTSD diagnosis include combat experience, physical, emotional, or sexual assault or abuse, accidents, and natural disasters. Women are twice as likely as men to be diagnosed with PTSD. Genetic influence appears to account for approximately 30-40% of risk.

Symptoms of PTSD

The symptoms of PTSD are usually divided into three categories:

  • Re-experiencing
  • Avoidance
  • Hyper-arousal

Re-experiencing symptoms arise when stimuli cause PTSD patients to relive their traumatic experience in flashbacks, frightening thoughts, or nightmares.

Avoidance symptoms arise when PTSD patients feel lack or emotion, lose interest in activities they once enjoyed, or withdraw from family and friends. These symptoms may be a result of trying to avoid reminders or triggers of the traumatic event.

Hyper-arousal symptoms appear as increased anxiety or feeling tense in safe environments. PTSD patients can be easily frightened, may have trouble sleeping, and may have frequent angry outbursts.

Nervous System Dysfunction

PTSD patients show differences in structure and function of certain brain regions compared to healthy controls. Not surprisingly, areas critical for the stress response are often altered. The hippocampus is involved in the recognition of environmental cues. The amygdala has a crucial role in the detection of threat, fear learning, fear expression and heightening memory for emotional events. The prefrontal cortex is involved in executive functions and decision making. In PTSD, these three regions are altered structurally and functionally. The hippocampus and prefrontal cortex show reduced activity and volume, and the amygdala has increased activity. These changes lead to the hippocampus and prefrontal cortex being less effective at inhibiting the stress response while the amygdala becomes more effective at activating it, resulting in increased stress sensitivity and a generalization of the fear response to non-threatening stimuli.

A sagittal brain section showing altered brain regions in PTSD. Details in text and caption.
Figure 40.1. PTSD patients show an underactive prefrontal cortex and hippocampus and an overactive amygdala. The sagittal section is taken slightly lateral to the midline of the brain. ‘PTSD Sagittal’ by Casey Henley is licensed under a Creative Commons Attribution Non-Commercial Share-Alike (CC BY-NC-SA) 4.0 International License.


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Foundations of Neuroscience Copyright © 2021 by Casey Henley is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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