Amygdala In Posttraumatic Stress Disorder Research Articles

Post-traumatic stress disorder: the role of the amygdala and potential therapeutic interventions - a review.

Post-traumatic stress disorder (PTSD) is a psychiatric disorder triggered by exposure to a life-threatening or sexually violent traumatic event, and is characterized by symptoms involving intrusive re-experiencing, persistent avoidance of associated stimuli, emotional and cognitive disturbances, and hyperarousal for long periods after the trauma has occurred. These debilitating symptoms induce occupational and social impairments that contribute to a significant clinical burden for PTSD patients, and substantial socioeconomic costs, reaching approximately $20,000 dollars per individual with PTSD each year in the US. Despite increased translational research focus in the field of PTSD, the development of novel, effective pharmacotherapies for its treatment remains an important unmet clinical need. In this review, we summarize the evidence implicating dysfunctional activity of the amygdala in the pathophysiology of PTSD. We identify the transient receptor potential canonical (TRPC) ion channels as promising drug targets given their distribution in the amygdala, and evidence from animal studies demonstrating their role in fear response modulation. We discuss the evidence-based pharmacotherapy and psychotherapy treatment approaches for PTSD. In view of the prevalence and economic burden associated with PTSD, further investigation is warranted into novel treatment approaches based on our knowledge of the involvement of brain circuitry and the role of the amygdala in PTSD, as well as the potential added value of combined pharmacotherapy and psychotherapy to better manage PTSD symptoms.

Efficacy and acceptability of noninvasive brain stimulation for treating posttraumatic stress disorder symptoms: A network meta-analysis of randomized controlled trials.

Despite its high lifetime prevalence rate and the elevated disability caused by posttraumatic stress disorder (PTSD), treatments exhibit modest efficacy. In consideration of the abnormal connectivity between the dorsolateral prefrontal cortex (DLPFC) and amygdala in PTSD, several randomized controlled trials (RCTs) addressing the efficacy of different noninvasive brain stimulation (NIBS) modalities for PTSD management have been undertaken. However, previous RCTs have reported inconsistent results. The current network meta-analysis (NMA) aimed to compare the efficacy and acceptability of various NIBS protocols in PTSD management. We systematically searched ClinicalKey, Cochrane Central Register of Controlled Trials, Embase, ProQuest, PubMed, ScienceDirect, Web of Science, and ClinicalTrials.gov to identify relevant RCTs. The targeted RCTs was those comparing the efficacy of NIBS interventions, such as transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), and transcutaneous cervical vagal nerve stimulation, in patients with PTSD. The NMA was conducted using a frequentist model. The primary outcomes were changes in the overall severity of PTSD and acceptability (to be specific, rates of dropouts for any reason). We identified 14 RCTs that enrolled 686 participants. The NMA demonstrated that among the investigated NIBS types, high-frequency rTMS over bilateral DLPFCs was associated with the greatest reduction in overall PTSD severity. Further, in comparison with the sham controls, excitatory stimulation over the right DLPFC with/without excitatory stimulation over left DLPFC were associated with significant reductions in PTSD-related symptoms, including depression and anxiety symptoms, and overall PTSD severity. This NMA demonstrated that excitatory stimulation over the right DLPFC with or without excitatory stimulation over left DLPFC were associated with significant reductions in PTSD-related symptoms. PROSPERO CRD42023391562.

Amygdala Nuclei Volume and Shape in Military Veterans With Posttraumatic Stress Disorder

BackgroundThe amygdala is a subcortical structure involved in socioemotional and associative fear learning processes relevant for understanding the mechanisms of posttraumatic stress disorder (PTSD). Research in animals indicates that the amygdala is a heterogeneous structure in which the basolateral and centromedial divisions are susceptible to stress. While the amygdala complex is implicated in the pathophysiology of PTSD, little is known about the specific contributions of the individual nuclei that constitute the amygdala complex. MethodsMilitary veterans (n = 355), including military veterans with PTSD (n = 149) and trauma-exposed control subjects without PTSD (n = 206), underwent high-resolution T1-weighted anatomical scans. Automated FreeSurfer segmentation of the amygdala yielded 9 structures: basal, lateral, accessory basal, anterior amygdaloid, and central, medial, cortical, and paralaminar nuclei, along with the corticoamygdaloid transition zone. Subregional volumes were compared between groups using ordinary-least-squares regression with relevant demographic and clinical regressors followed by 3-dimensional shape analysis of whole amygdala. ResultsPTSD was associated with smaller left and right lateral and paralaminar nuclei, but with larger left and right central, medial, and cortical nuclei (p < .05, false discovery rate corrected). Shape analyses revealed lower radial distance in anterior bilateral amygdala and lower Jacobian determinant in posterior bilateral amygdala in PTSD compared with control subjects. ConclusionsAlterations in select amygdala subnuclear volumes and regional shape distortions are associated with PTSD in military veterans. Volume differences of the lateral nucleus and the centromedial complex associated with PTSD demonstrate a subregion-specific pattern that is consistent with their functional roles in fear learning and fear expression behaviors.

Effects of calcium-dependent molecular chaperones and endoplasmic reticulum in the amygdala in rats under single‑prolonged stress.

The purpose of the present study was to investigate the role of endoplasmic reticulum (ER)‑resident molecular chaperone proteins to identify whether these proteins were involved in post‑traumatic stress disorder (PTSD). The present study detected changes of calreticulin (CRT), calnexin (CNX) and ERp57 in the amygdala of rats, which may with aim of providing a novel insight into the modulation effect of amygdala in PTSD. Single‑prolonged stress (SPS) was applied to create the models of PTSD in rats. The expression levels of CRT, CNX and ERp57 were examined using immunohistochemistry or immunofluorescence, western blot analysis and reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). The results showed that SPS induced significant changes in CRT, CNX and ERp57 expression levels. Furthermore, the expression levels of CRT, CNX and ERp57 were significantly upregulated when compared to that in the control group after SPS exposure by western blot analysis (P<0.05). RT‑qPCR analysis supported these results, indicating an upregulation of mRNA expression level. Taken together, the present findings suggest that SPS may induce changes to the expression of CRT, CNX and ERp57 in the amygdala of rats. The present study provides an insight into the effects of ER‑resident molecular chaperones in the amygdala participating in PTSD, and provides the experimental basis and a mechanism for the pathophysiology of PTSD.

Alterations in cyclinD1 and cyclin‑dependent kinase 4 expression in the amygdalae of post‑traumatic stress disorder rats.

The amygdalae are an important component of the human limbic system and exhibit a key role in emotional and behavioral reactions. Previous studies have demonstrated abnormal function and morphology in the amygdalae of post‑traumatic stress disorder (PTSD)‑like animal models, however the underlying molecular mechanisms remain elusive. The authors have previously demonstrated that PTSD induced increased apoptosis in the amygdala of PTSD‑like animals. CyclinD1 and cyclin‑dependent kinase4 (CDK4) are two important regulators of the cell cycle. The study explored the expression of cyclinD1 and CDK4 in the amygdala in PTSD. The single‑prolonged stress (SPS) rat model was used as a PTSD‑like model. Ultrastructural alterations of cells in the amygdala were observed using transmission electron microscopy (TEM). 4',6‑Diamidino‑2‑phenylindole (DAPI) fluorescence was employed to detect nuclear pycnosis. CyclinD1 and CDK4 expression in the amygdala cells was examined using immunofluorescence, Western blotting and reverse transcription‑quantitative polymerase chain reaction. TEM revealed morphological alterations to the amygdala cells of the SPS rats. DAPI‑stained nuclear brightness levels differed between the control and SPS groups. Expression of cyclinD1 and CDK4 in the amygdala increased gradually 1day and 4days following SPS stimulation, and peaked 7days following SPS stimulation at the protein and mRNA levels, in comparison with the control rats. These findings suggest that SPS resulted in increased cyclinD1 and CDK4 expression, which may accelerate cell apoptosis. This may be associated with SPS‑induced abnormal function and structure of the amygdala.

Intranasal Oxytocin Normalizes Amygdala Functional Connectivity in Posttraumatic Stress Disorder.

The neuropeptide oxytocin (OT) has been suggested as a promising pharmacological agent for medication-enhanced psychotherapy in posttraumatic stress disorder (PTSD) because of its anxiolytic and prosocial properties. We therefore investigated the behavioral and neurobiological effects of a single intranasal OT administration (40 IU) in PTSD patients. We conducted a randomized, placebo-controlled, cross-over resting-state fMRI study in male and female police officers with (n=37, 21 males) and without PTSD (n=40, 20 males). We investigated OT administration effects on subjective anxiety and functional connectivity of basolateral (BLA) and centromedial (CeM) amygdala subregions with prefrontal and salience processing areas. In PTSD patients, OT administration resulted in decreased subjective anxiety and nervousness. Under placebo, male PTSD patients showed diminished right CeM to left ventromedial prefrontal cortex (vmPFC) connectivity compared with male trauma-exposed controls, which was reinstated after OT administration. Additionally, female PTSD patients showed enhanced right BLA to bilateral dorsal anterior cingulate cortex (dACC) connectivity compared with female trauma-exposed controls, which was dampened after OT administration. Although caution is warranted, our findings tentatively suggest that OT has the potential to diminish anxiety and fear expression of the amygdala in PTSD, either via increased control of the vmPFC over the CeM (males) or via decreased salience processing of the dACC and BLA (females). Our findings add to accumulating evidence that OT administration could potentially enhance treatment response in PTSD.

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

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.

Decreased regional cerebral blood flow in medial prefrontal cortex during trauma-unrelated stressful imagery in Vietnam veterans with post-traumatic stress disorder

Neuroimaging research has demonstrated medial prefrontal cortex (mPFC) hyporesponsivity and amygdala hyperresponsivity to trauma-related or emotional stimuli in post-traumatic stress disorder (PTSD). Relatively few studies have examined brain responses to the recollection of stressful, but trauma-unrelated, personal events in PTSD. In the current study, we sought to determine whether regional cerebral blood flow (rCBF) abnormalities in mPFC and amygdala in PTSD could be observed during the recollection of trauma-unrelated stressful personal events. Participants were 35 right-handed male combat veterans (MCVs) and female nurse veterans (FNVs) who served in Vietnam: 17 (seven male, 10 female) with current military-related PTSD and 18 (nine male, nine female) with no current or lifetime PTSD. We used positron emission tomography (PET) and script-driven imagery to study rCBF during the recollection of trauma-unrelated stressful versus neutral and traumatic events. Voxelwise tests revealed significant between-group differences for the trauma-unrelated stressful versus neutral comparison in mPFC, specifically in the anterior cingulate cortex (ACC). Functional region of interest (ROI) analyses demonstrated that this interaction in mPFC represented greater rCBF decreases in the PTSD group during trauma-unrelated stressful imagery relative to neutral imagery compared to the non-PTSD group. No differential amygdala activation was observed between groups or in either group separately. Veterans with PTSD, compared to those without PTSD, exhibited decreased rCBF in mPFC during mental imagery of trauma-unrelated stressful personal experiences. Functional neuroanatomical models of PTSD must account for diminished mPFC responses that extend to emotional stimuli, including stressful personal experiences that are not directly related to PTSD.

Role of phosphorylated ERK in amygdala neuronal apoptosis in single-prolonged stress rats

Studies have shown that single-prolonged stress (SPS) can induce the apoptotic process in the amygdala. In the present study, we aimed to detect expression of phosphorylated p44/42 extracellular signal-regulated kinase (pERK1/2) and apoptosis-related Bax and Bcl-2 and apoptotic cell death in the amygdala region in SPS rats as well as the relation between pERK1/2 and apoptosis. A total of 75 male Wistar rats were randomly divided into control, SPS and PD98059-SPS groups. Rats in the SPS and PD98059-SPS groups were treated with the SPS procedure and were injected with solvent or PD98059 (an inhibitor of ERK), respectively, into the amygdala 30min before exposure to SPS. The expression of pERK1/2 was detected using immunohistochemistry and Western blotting. The expression of Bax and Bcl-2 was detected using Western blotting and RT-PCR; TUNEL-staining was employed for the detection of apoptotic cells in the amygdala. The results showed that the expression of pERK1/2, the ratio of Bax/Bcl-2 and the TUNEL-positive cell rate significantly increased in the SPS group. After the rats were infused with PD98059, these indices were abolished. In the SPS rat brain, we found that the apoptotic process in the amygdala region was induced by pERK1/2, and this may be related to the abnormal function of the amygdala in post-traumatic stress disorder.

Dysfunction of Ca2+/CaM kinase IIα cascades in the amygdala in post-traumatic stress disorder

Single-prolonged stress (SPS) is an established animal model for post-traumatic stress disorder (PTSD). The calcium (Ca2+)-calmodulin (CaM)-CaM kinase (K)IIalpha signal passage plays an important role in the plasticity of central nervous, learning and memory, mind and behavior and other types of cognitive activities. The amygdala is known to play an important role in fear, rage and emotional memory. In this study, we investigated changes in Ca2+-CaM-CaMKIIalpha in the basolateral amygdala of rats after SPS which may reveal part of the pathogenesis of PTSD. The intracellular free calcium level in the basolateral amygdala was examined by fluorescence spectrophotometry. CaM and CaMKIIalpha expression in basolateral amygdala was examined using immunohistochemistry, Western blotting and reverse transcription-polymerase chain reaction. The intracellular free calcium level in the basolateral amygdala was increased when compared to that in the control group 1 day after SPS exposure (P<0.05). CaM expression significantly increased, and CaMKIIalpha expression significantly decreased (P<0.05) in the basolateral amygdala after SPS. These findings suggest dysfunction of Ca2+-CaM-CaMKIIalpha in the basolateral amygdala of SPS rats, which may play important roles in the pathogenesis of PTSD rats.

An fMRI investigation of memory encoding in PTSD: Influence of symptom severity

Previous studies have shown memory deficits in Post-Traumatic Stress Disorder (PTSD) patients, as well as abnormal patterns of brain activity, especially when retrieving trauma-related information. This study extended previous findings by investigating the neural correlates of successful memory encoding of trauma-unrelated stimuli and their relationship with PTSD symptom severity. We used the subsequent memory paradigm, in the context of event-related functional magnetic resonance imaging, in 27 PTSD patients to identify the brain regions involved in the encoding of fearful and neutral faces. Symptom severity was assessed by the Clinically Administered PTSD Scale (CAPS) scores. It was found that memory performance was negatively correlated with CAPS scores. Furthermore, a negative correlation was observed between CAPS scores and ventral medial prefrontal cortex (vmPFC) activity elicited by the subsequently forgotten faces. Finally, symptom severity predicted the contribution of the amygdala to the successful encoding of fearful faces. These results confirm the roles of the vmPFC and the amygdala in PTSD and highlight the importance of taking into account individual differences when assessing the behavioural and neural correlates of the disorder.

Functional connectivity of the prefrontal cortex and the amygdala in posttraumatic stress disorder

Functional connectivity of the prefrontal cortex and the amygdala in posttraumatic stress disorder

Functional connectivity of the prefrontal cortex and the amygdala in posttraumatic stress disorder

Background Persistent, intrusive re-experiencing in posttraumatic stress disorder (PTSD) is commonly construed as a failure of cingulate inhibition (i.e., extinction) over a hyperresponsive amygdala, based primarily on animal research of fear conditioning and the finding of cingulate hypoperfusion in PTSD. Methods We examined functional connectivity in patients with PTSD and healthy trauma survivors during repeated symptom provocation using H 2O 15 positron emission tomography. Results Memory retrieval networks (right prefrontal cortex, hippocampus, and visual cortex) were common to both groups. Networks supporting autonomic and emotional control and preparatory motor action (amygdala, anterior cingulate, subcallosal gyrus, and premotor cortex) differed between the two groups and became progressively disparate with successive presentations of the traumatic script. Patterns of effective connectivity demonstrated the predominance of direct influences of the amygdala on visual cortex, subcallosal gyrus, and anterior cingulate in PTSD but not in control subjects. There was little evidence for failure of inhibition of cingulate or subcallosal cortex over the amygdala. Conclusions These patterns might represent excessive influences of the amygdala over regions involved in autonomic, and higher-order visual memory processing in PTSD. The present data suggest that inferences of direct correspondence between animal studies and pathophysiology of PTSD should be made with caution.