Post-traumatic stress disorder, or PTSD, is a disorder that develops after someone experiences a traumatic event; it involves a variety of intrusive symptoms related to the trauma. In this video, I discuss hypotheses about what might be going on in the brain to cause PTSD.
TRANSCRIPT:
Post-traumatic stress disorder, or PTSD, is a condition that develops after someone experiences a traumatic event. It involves the occurrence of intrusive symptoms like nightmares or distressing memories that are linked to the trauma and may cause the person to feel like they are reliving aspects of the traumatic event. These symptoms also lead to the avoidance of things that remind a person of the trauma. PTSD may cause various other issues such as difficulty sleeping, negative emotions like fear, guilt, or sadness, trouble concentrating, and irritability.
Although the neurocircuitry underlying PTSD is still not completely clear, one supported hypothesis suggests that PTSD involves decreased activity in the medial prefrontal cortex and increased activity in subnuclei of the amygdala that are involved in the identification of threats. According to this hypothesis, the medial prefrontal cortex normally acts to regulate amygdala function, inhibiting it when there is not an immediate threat to devote attention to. In an individual with PTSD, however, the amygdala might be hyperactive and provoke a fearful reaction in response to trauma-related stimuli. The medial prefrontal cortex fails to inhibit this unnecessary amygdala activation, causing patients to experience responses that are disproportionate to the threat that trauma-related stimuli currently pose.
Some patients with PTSD, however, also experience the suppression of emotions, which causes symptoms like social detachment and emotional numbness. This might be caused by an opposing mechanism where increased activity in the medial prefrontal cortex dampens activity in regions such as the amygdala and other areas involved in emotional expression. Thus, the neuroscience of the disorder is complex and the neurocircuitry involved likely depends on the symptoms a particular patient displays. Additionally, more recent research has suggested a role for other networks that span larger areas of the brain in bringing about the symptoms of PTSD.
REFERENCES:
Etkin A, Wager TD. Functional neuroimaging of anxiety: a meta-analysis of emotional processing in PTSD, social anxiety disorder, and specific phobia. Am J Psychiatry. 2007 Oct;164(10):1476-88. doi: 10.1176/appi.ajp.2007.07030504. PMID: 17898336; PMCID: PMC3318959.
Rauch SL, Shin LM, Whalen PJ, Pitman RK. Neuroimaging and the Neuroanatomy of Posttraumatic Stress Disorder. CNS Spectrums. 1998 July/August;3(7):31-41.
Yehuda R, Hoge CW, McFarlane AC, Vermetten E, Lanius RA, Nievergelt CM, Hobfoll SE, Koenen KC, Neylan TC, Hyman SE. Post-traumatic stress disorder. Nat Rev Dis Primers. 2015 Oct 8;1:15057. doi: 10.1038/nrdp.2015.57. PMID: 27189040.
