Dysfunctional or hyperfunctional? The amygdala in posttraumatic stress disorder is the bull in the evolutionary China shop

Abstract

Our motivation in writing this Review arose not only from the great value in contributing to this special issue of the Journal of Neuroscience Research but also from the desire to express our opinion that the description of the amygdala as "dysfunctional" in posttraumatic stress disorder (PTSD) might not be appropriate. We acknowledge that excessive activation of the amygdala contributes to the cluster of PTSD symptoms, including hypervigilance, intrusive memories, and impaired sleep, that underlies the devastating mental and physical outcomes in trauma victims. The issue that we address is whether the symptoms of PTSD represent an impaired (dysfunctional) or sensitized (hyperfunctional) amygdala status. We propose that the amygdala in PTSD is hyperfunctional rather than dysfunctional in recognition of the fact that the individual has already survived one life-threatening attack and that another may be forthcoming. We therefore consider PTSD to be a state in which the amygdala is functioning optimally if the goal is to ensure a person's survival. The misery caused by a hyperfunctional amygdala in PTSD is the cost of inheriting an evolutionarily primitive mechanism that considers survival more important than the quality of one's life.

The Anti-Inflammatory Effects of Blueberries in an Animal Model of Post-Traumatic Stress Disorder (PTSD)

“…It is the 4 th most common psychiatric disorder, with a lifetime prevalence rate of 6.8% in the US [4]. The clinical manifestations of PTSD are characterized by intense fear, helplessness and horror following repeated experience of flashback memories and leads to elusive behavior [5, 6]. In the past decade extraordinary progress has been made to understand the pathogenesis of PTSD, but it is not yet completely clear [7].…”

Predator-based psychosocial stress animal model of PTSD: Preclinical assessment of traumatic stress at cognitive, hormonal, pharmacological, cardiovascular and epigenetic levels of analysis

“…If we consider BDNF production as an important component of local synaptic structure, plasticity and overall functioning, then the imbalance of BDNF production between the hippocampus and amygdala would be consistent with our recent speculation regarding PTSD as an imbalance between amygdala and prefrontal cortical functioning (Diamond and Zoladz, 2016) We hypothesized that the hyper-functional status of the amygdala in PTSD is adaptive, from an evolutionary perspective, as a means with which to maintain heightened vigilance in a potentially hostile environment. The resistance of the amygdala to exhibit hypermethylation of the BDNF gene, and therefore to generate normal levels of BDNF, would enable this structure to continue to serve the function of maximizing one's vigilance, and to maintain memories of the trauma in an active state, following exposure to a life-threatening event.…”

“…The resistance of the amygdala to exhibit hypermethylation of the BDNF gene, and therefore to generate normal levels of BDNF, would enable this structure to continue to serve the function of maximizing one's vigilance, and to maintain memories of the trauma in an active state, following exposure to a life-threatening event. The differential expression of epigenetic modification to the hippocampus and prefrontal cortex versus amygdala may underlie the combination of amygdala-based hypervigilance and intrusive memories of trauma in conjunction with impaired hippocampal-prefrontal based processing of new information in people with PTSD (Diamond and Zoladz, 2016;Samuelson, 2011;.…”

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“…Diamond and Zoladz described the amygdala in PTSD as ''the bull in the evolutionary China shop.'' 16 The misery experienced by the victim is a hyperfunctioning survival state that is abnormal under calm conditions. 16 In a 2008 article, Bryant, et al reported that approximately half of patients with PTSD did not respond to cognitive-behavioral therapy (CBT), which was considered the conventional treatment of choice at the time.…”

“…16 The misery experienced by the victim is a hyperfunctioning survival state that is abnormal under calm conditions. 16 In a 2008 article, Bryant, et al reported that approximately half of patients with PTSD did not respond to cognitive-behavioral therapy (CBT), which was considered the conventional treatment of choice at the time. The researchers cited an excessive amygdala response to fear as a key factor in the suboptimal CBT success rate.…”