About 10 percent of women and 4 percent of men will develop Post-Traumatic Stress Disorder (PTSD) over their lifetimes. Men and women who have experienced sexual trauma are at increased risk, especially if the trauma occurred at a young age or was repeated.
PTSD is a mental health condition that may involve disturbances in threat perception, threat sensitivity, self-image, and emotional functioning. It can cause serious disruption in the ability to have healthy, satisfying relationships or tolerate life’s uncertainties, failures, and rejections without excess distress. It can also cause phobias, sleep disturbance, negative mood, anxiety, and attention/concentration difficulties that interfere with academic or career success. Research in neuroscience suggests impaired functioning in brain areas responsible for threat detection/response and emotion regulation account for many PTSD symptoms.
What Is PTSD?
PTSD is a mental health condition that can develop in response to a trauma that may have occurred recently or in the distant past. Generally, the trauma would involve some sense of threat to life or threat of bodily harm affecting either you or a loved one. Core symptoms of PTSD include some type of re-experiencing (e.g., nightmares, flashbacks, or emotional flooding), attempts to avoid reminders of the event or associated emotions, hyper-arousal (e.g., feeling constantly on edge), and distressing thoughts or emotional reactions. These symptoms need to last for at least two weeks and interfere with functioning or cause significant distress.
What Brain Areas are Implicated in PTSD?
PTSD symptoms develop due to dysfunction in two key regions:
This is a small almond-shaped structure located deep in the middle of the temporal lobe. The amygdala is designed to:
- Detect threats in the environment and activate the “fight or flight” response
- Activate the sympathetic nervous system to help you deal with the threat
- Help you store new emotional or threat-related memories
The Prefrontal Cortex (PFC)
The Prefrontal Cortex is located in the frontal lobe just behind your forehead. The PFC is designed to:
- Regulate attention and awareness
- Make decisions about the best response to a situation
- Initiate conscious, voluntary behavior
- Determine the meaning and emotional significance of events
- Regulate emotions
- Inhibit or correct dysfunctional reactions
When your brain detects a threat, the amygdala initiates a quick, automatic defensive (“fight or flight”) response involving the release of adrenaline, norepinephrine, and glucose to rev up your brain and body. Should the threat continue, the amygdala communicates with the hypothalamus and pituitary gland to release cortisol. Meanwhile, the medial part of the prefrontal cortex consciously assesses the threat and either accentuates or calms down the “fight or flight” response.
Studies of response to threat in people with PTSD show:
- A hyper reactive amygdala
- A less activated medial PFC
In other words, the amygdala reacts too strongly to a potential threat while the medial PFC is impaired in its ability to regulate the threat response.
Consequences of Brain Dysfunctions in PTSD
Because the amygdala is overactive, more norepinephrine is released in response to threat and its release is not well-regulated by the PFC.
Effects of excess norepinephrine include:
- Increased wakefulness and sleep disruption
As a result of hyperarousal, people with PTSD can get emotionally triggered by anything that resembles the original trauma (e.g., a sexual assault survivor telling her story on TV, a loud noise, or passing somebody who looks like their assailant). Symptoms of hypervigilance means they are frequently keyed up and on edge, while increased wakefulness means they may have difficulty sleeping or wake up in the middle of the night.
Reactive Anger and Impulsivity
A reactive amygdala keeps people with PTSD on the alert and ready for quick action when they face a threat, leading them to be more impulsive. The orbital PFC is a part of the PFC that can inhibit motor behavior (physical action) when it is not appropriate or necessary. In people with PTSD, the orbital PFC has lower volume and is less activated. This means that people with PTSD have less control over reactive anger and impulsive behaviors when they are emotionally triggered. Reactive anger can cause damage to career success and interfere with relationship functioning.
Increased Fear and Anger and Decreased Positive Emotionality
People with PTSD often report feeling an excess of negative emotion and little positive emotion. They may have difficulty enjoying their day-to-day activities and interactions. This could be the result of a hyperactive amygdala communicating with the insula, an area of the brain associated with introspection and emotional awareness. The amygdala-insula circuit also impacts the medial PFC, an area associated with assigning meaning to events and regulating emotions. Research shows overactivity of the amygdala-amygdala-insult circuit can suppress the medial PFC, thereby interfering with the ability to regulate negative emotions and assign more positive meaning to events.
How Treatments Affect the Brains of People with PTSD
Some studies show that psychotherapies which include repeated exposure to trauma cues can enhance the ability of the PFC to assign less threatening or more positive meanings to trauma-related events. Antidepressants seem to have a similar effect. Mindfulness interventions lasting 10 to 12 weeks have been shown to decrease amygdala volume and increase the connectivity between the amygdala and PFC. Mindfulness seems to make the amygdala less reactive and the PFC more able to calm down the threat response. But some people with PTSD may have difficulty tolerating being mindful or confronting their trauma actively. Avoidance is a hallmark of PTSD and some patients may need more support and relationship-building before they are ready to face their distressing feelings.
Research suggests that the brains of people with PTSD differ from brains of those without PTSD in two main ways:
- They are hyperactive to threat (amygdala).
- They have difficulty regulating or damping down anxiety and anger (medial PFC).
Effective treatments for PTSD seem to address these brain dysfunctions by either decreasing the reactivity of the amygdala or increasing the ability of the PFC to calm it down. Therapists who are trained to recognize and treat the signs of PTSD can be much more effective in reducing the considerable suffering associated with their trauma experience. Educating patients about their symptoms and the neurobiology of PTSD can be de-shaming and increase their self-compassion and sense of control.
Southwick, S. M., Davis., L. L., Aikins, D. E., Rasmusson, A., Barron, J., Morgan, C. A. (2007) Neurobiological alterations associated with PTSD in Handbook of PTSD: Science and practice . Edited by Friedman MJ;
Keane TM; Resick PA. New York, Guilford Press, 2007, pp165-189
Shin LM, Rauch SL, Pitman RK. Amygdala, medial prefrontal cortex, and hippocampal function in PTSD. Ann N Y Acad Sci. 2006;1071:67–79. [PubMed]
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