High dose hydrocortisone immediately after trauma may alter the trajectory of PTSD: interplay between clinical and animal studies

Forebrain overexpression of type 1 adenylyl cyclase promotes molecular stability and behavioral resilience to physical stress

The ability to cope with stress is essential for emotional stability and mental health. It is also hypothesized that factors promoting resilience to stress may offer treatment strategies for maladaptive disorders such as anxiety and depression. Here, we find that physical restraint reduces the expression of type 1 adenylyl cyclase (Adcy1), a neurospecific synaptic enzyme that positively regulates the cAMP signaling cascade. Conversely, an increase of forebrain Adcy1 expression in transgenic mouse (i.e., Adcy1 ^tg mouse) predisposes individuals to molecular stability and behavioral resilience. Transgenic overexpression of Adcy1 prevents the physical restraint-induced down-regulation of brain-derived neurotrophic factor (BDNF) and neuropeptide Y (NPY). Further, Adcy1 ^tg mice maintain regular locomotive activity in novelty exploration and voluntary wheel running following physical restraint. Adcy1 ^tg mice show higher corticosterone and lower basal glucocorticoid receptor (GR) expression, along with a higher MR (mineralocorticoid receptor) to GR ratio in the hippocampus. Further, Adcy1 ^tg mice show reduced immobility under acute physical stress conditions in the forced swimming test and are more sensitive to the antidepressant desipramine. Our results demonstrate a novel function of Adcy1 in stress coping and suggest Adcy1 as a potential target to antagonize stress vulnerability and promote antidepressant efficacy.

Rodent models of post-traumatic stress disorder: behavioral assessment

Although the etiology and expression of psychiatric disorders are complex, mammals show biologically preserved behavioral and neurobiological responses to valent stimuli which underlie the use of rodent models of post-traumatic stress disorder (PTSD). PTSD is a complex phenotype that is difficult to model in rodents because it is diagnosed by patient interview and influenced by both environmental and genetic factors. However, given that PTSD results from traumatic experiences, rodent models can simulate stress induction and disorder development. By manipulating stress type, intensity, duration, and frequency, preclinical models reflect core PTSD phenotypes, measured through various behavioral assays. Paradigms precipitate the disorder by applying physical, social, and psychological stressors individually or in combination. This review discusses the methods used to trigger and evaluate PTSD-like phenotypes. It highlights studies employing each stress model and evaluates their translational efficacies against DSM-5, validity criteria, and criteria proposed by Yehuda and Antelman's commentary in 1993. This is intended to aid in paradigm selection by informing readers about rodent models, their benefits to the clinical community, challenges associated with the translational models, and opportunities for future work. To inform PTSD model validity and relevance to human psychopathology, we propose that models incorporate behavioral test batteries, individual differences, sex differences, strain and stock differences, early life stress effects, biomarkers, stringent success criteria for drug development, Research Domain Criteria, technological advances, and cross-species comparisons. We conclude that, despite the challenges, animal studies will be pivotal to advances in understanding PTSD and the neurobiology of stress.

The role of catecholamines in modulating responses to stress: Sex-specific patterns, implications, and therapeutic potential for post-traumatic stress disorder and opiate withdrawal

Emotional arousal is one of several factors that determine the strength of a memory and how efficiently it may be retrieved. The systems at play are multifaceted; on one hand, the dopaminergic mesocorticolimbic system evaluates the rewarding or reinforcing potential of a stimulus, while on the other, the noradrenergic stress response system evaluates the risk of threat, commanding attention, and engaging emotional and physical behavioral responses. Sex-specific patterns in the anatomy and function of the arousal system suggest that sexually divergent therapeutic approaches may be advantageous for neurological disorders involving arousal, learning, and memory. From the lens of the triple network model of psychopathology, we argue that post-traumatic stress disorder and opiate substance use disorder arise from maladaptive learning responses that are perpetuated by hyperarousal of the salience network. We present evidence that catecholamine-modulated learning and stress-responsive circuitry exerts substantial influence over the salience network and its dysfunction in stress-related psychiatric disorders, and between the sexes. We discuss the therapeutic potential of targeting the endogenous cannabinoid system; a ubiquitous neuromodulator that influences learning, memory, and responsivity to stress by influencing catecholamine, excitatory, and inhibitory synaptic transmission. Relevant preclinical data in male and female rodents are integrated with clinical data in men and women in an effort to understand how ideal treatment modalities between the sexes may be different.

Cannabinoids as therapeutics for PTSD

Post-traumatic stress disorder (PTSD) is a complex disorder that involves dysregulation of multiple neurobiological systems. The traumatic stressor plays a causal role in producing psychological dysfunction and the pattern of findings suggests that the hypothalamic-pituitary-adrenal (HPA) axis, which is instrumental for stress adaptation, is critically dysfunctional in PTSD. Given the lack of understanding of the basic mechanisms and underlying pathways that cause the disorder and its heterogeneity, PTSD poses challenges for treatment. Targeting the endocannabinoid (ECB) system to treat mental disorders, and PTSD in particular, has been the focus of research and interest in recent years. The ECB system modulates multiple functions, and drugs enhancing ECB signaling have shown promise as potential therapeutic agents in stress effects and other psychiatric and medical conditions. In this review, we focus on the interaction between the ECB-HPA systems in animal models for PTSD and in patients with PTSD. We summarize evidence supporting the use of cannabinoids in preventing and treating PTSD in preclinical and clinical studies. As the HPA system plays a key role in the mediation of the stress response and the pathophysiology of PTSD, we describe preclinical studies suggesting that enhancing ECB signaling is consistent with decreasing PTSD symptoms and dysfunction of the HPA axis. Overall, we suggest that a pharmacological treatment targeted at one system (e.g., HPA) may not be very effective because of the heterogeneity of the disorder. There are abnormalities across different neurotransmitter systems in the pathophysiology of PTSD and none of these systems function uniformly among all patients with PTSD. Hence, conceptually, enhancing ECB signaling may be a more effective avenue for pharmacological treatment.

Effects of agomelatine on behaviour, circadian expression of period 1 and period 2 clock genes and neuroplastic markers in the predator scent stress rat model of PTSD

Objectives: The therapeutic value of the antidepressant agomelatine in the aftermath of traumatic experience and early post-reminder has been questioned. Herein, agomelatine, its vehicle or melatonin agonist were administered either acutely 1 h post-stressor or repeatedly (7 days) after early post-reminder in a post-traumatic stress rat model (PSS) using the scent of predator urine.Methods: Behavioural responses, and brain molecular and morphological changes were evaluated after each treatment procedure in PSS-exposed and unexposed rats.Results: When administered immediately after PSS, agomelatine induced a significant reduction of anxiety-like behaviour as assessed in the elevated-plus-maze and acoustic startle response at 8 days post-administration. Concomitantly, agomelatine significantly decreased Per1/Per2 expression in the CA1/CA3 areas, suprachiasmatic nucleus and basolateral amygdala, thereby partially restoring genes expression overregulated by PSS. Agomelatine further significantly increased cell growth and facilitated dendritic growth and arbour in dentate gyrus (DG) granule and apical CA1 cells and upregulated brain-derived neurotrophic factor protein in the DG and cortex III versus vehicle. When administered early post-reminder over 7 days before testing, agomelatine was ineffective on behavioural responses pattern, molecular and morphological changes induced by PSS.Conclusions: These findings suggest that agomelatine may be a potential agent in the acute aftermath of traumatic stress exposure.

Significance of the orexinergic system in modulating stress-related responses in an animal model of post-traumatic stress disorder

Converging evidence indicates that orexins (ORXs), the regulatory neuropeptides, are implicated in anxiety- and depression-related behaviors via the modulation of neuroendocrine, serotonergic, and noradrenergic systems. This study evaluated the role of the orexinergic system in stress-associated physiological responses in a controlled prospective animal model. The pattern and time course of activation of hypothalamic ORX neurons in response to predator-scent stress (PSS) were examined using c-Fos as a marker for neuronal activity. The relationship between the behavioral response pattern 7 days post-exposure and expressions of ORXs was evaluated. We also investigated the effects of intracerebroventricular microinfusion of ORX-A or almorexant (ORX-A/B receptor antagonist) on behavioral responses 7 days following PSS exposure. Hypothalamic levels of ORX-A, neuropeptide Y (NPY), and brain-derived neurotrophic factor (BDNF) were assessed. Compared with rats whose behaviors were extremely disrupted (post-traumatic stress disorder [PTSD]-phenotype), those whose behaviors were minimally selectively disrupted displayed significantly upregulated ORX-A and ORX-B levels in the hypothalamic nuclei. Intracerebroventricular microinfusion of ORX-A before PSS reduced the prevalence of the PTSD phenotype compared with that of artificial cerebrospinal fluid or almorexant, and rats treated with almorexant displayed a higher prevalence of the PTSD phenotype than did untreated rats. Activated ORX neurons led to upregulated expressions of BDNF and NPY, which might provide an additional regulatory mechanism for the modulation of adaptive stress responses. The study indicates that the activated ORX system might promote adaptive responses to PSS probably via stimulation of BDNF and NPY secretion, and early intervention with ORX-A reduces the prevalence of the PTSD phenotype and increases the prevalence of adaptive phenotypes. The findings provide some insights into the mechanisms underlying the involvement of the ORX system in stress-related disorders.

Vulnerable and resilient cognitive performance related to early life stress: The potential mediating role of dopaminergic receptors in the medial prefrontal cortex of adult mice

RATIONALE

Exposure to early life stress (ELS) is known to have pronounced effects on the prefrontal cortex (PFC). However, not all individuals exposed to ELS manifest the same neurobiological and cognitive phenotypes when adults. Dopamine signaling could be a key factor in understanding the effects of stress on PFC-related cognitive function.

OBJECTIVES

We aimed to investigate the differential effects of ELS on cognitive performance of adult mice and the dopaminergic receptors expression in the PFC.

METHODS

BALB/c males were exposed to the maternal separation (MS) procedure and their cognitive performance on the eight-arm radial maze (8-RAM) were assessed during adulthood. For molecular-level assessments, we performed mRNA expression analyses for dopamine receptors-DRD1, DRD2, DRD3-and Hers1 expression in the medial PFC.

RESULTS

While MS produced an overall impairment on 8-RAM, the stressed animals could be divided in two groups based on their performance: those with impaired cognitive performance (vulnerable to maternal separation, V-MS) and those without any impairment (resilient to maternal separation, R-MS). V-MS animals showed increased DRD1 and DRD2 expression in comparison with other groups. Errors on 8-RAM were also positively correlated with DRD1 and DRD2 mRNA expression.

CONCLUSIONS

Our findings suggest a potential role of the dopaminergic system in the programming mechanisms of cognitive vulnerability and resilience related to ELS.

Pharmacological prevention and early treatment of post-traumatic stress disorder and acute stress disorder: a systematic review and meta-analysis

Post-traumatic stress disorder (PTSD) is a common mental disorder associated with significant distress and reduced functioning. Its occurrence after a severe traumatic event and association with characteristic neurobiological changes make PTSD a good candidate for pharmacological prevention and early treatment. The primary aim for this systematic review and meta-analysis was to assess whether pharmacological interventions when compared to placebo, or other pharmacological/psychosocial interventions resulted in a clinically significant reduction or prevention of symptoms, improved functioning or quality of life, presence of disorder, or adverse effects. A systematic search was undertaken to identify RCTs, which used early pharmacotherapy (within three months of a traumatic event) to prevent and treat PTSD and acute stress disorder (ASD) in children and adults. Using Cochrane Collaboration methodology, RCTs were identified and rated for risk of bias. Available data was pooled to calculate risk ratios (RR) for PTSD prevalence and standardised mean differences (SMD) for PTSD severity. 19 RCTs met the inclusion criteria; 16 studies with adult participants and three with children. The methodological quality of most trials was low. Only hydrocortisone in adults was found to be superior to placebo (3 studies, n = 88, RR: 0.21 (CI 0.05 to 0.89)) although this was in populations with severe physical illness, raising concerns about generalisability. No significant effects were found for the other pharmacotherapies investigated (propranolol, oxytocin, gabapentin, fish oil (1470 mg DHA/147 mg EPA), fish oil (224 mg DHA/22.4 mg EPA), dexamethasone, escitalopram, imipramine and chloral hydrate). Hydrocortisone shows the most promise, of pharmacotherapies subjected to RCTs, as an emerging intervention in the prevention of PTSD within three months after trauma and should be a target for further investigation. The limited evidence for hydrocortisone and its adverse effects mean it cannot be recommended for routine use, but, it could be considered as a preventative intervention for people with severe physical illness or injury, shortly after a traumatic event, as long as there are no contraindications. More research is needed using larger, high quality RCTs to establish the most efficacious use of hydrocortisone in different populations and optimal dosing, dosing window and route. There is currently a lack of evidence to suggest that other pharmacological agents are likely to be effective.

The effect of steroid treatment on whiplash associated syndrome: a controlled randomized prospective trial

PURPOSE

There is significant evidence in the literature that low or relatively low cortisol concentrations near the time of an accident are associated with more severe forms of whiplash-associated disorders. We hypothesized that treating patients that were involved in a motor vehicle accident with hydrocortisone would alleviate the incidence and severity of these disabling disorders.

METHODS

A prospective, randomized, double-blind, placebo-controlled clinical trial. Blunt trauma patients that underwent a motor vehicle crash were allocated into a study group that received a single bolus of hydrocortisone and a control group that received saline. The patients were followed for 1 month. The incidence and severity of whiplash associated disorder, functional disturbances, and post-traumatic stress disorder were compared between the two groups. The analyses were repeated for sub-divisions into groups of high and low admission cortisol.

RESULTS

The more severe forms of whiplash-associated disorders on the day of accident were associated with low cortisol levels; mean cortisol concentration of the lower grade of whiplash patients (13.09 ± 7.35 µg%) was higher than that of whiplash syndrome of the severe forms (8.33 ± 3.45 µg), p = 0.001. There were no differences between study and control groups regarding whiplash-associated disorders, functional tests, and severity of stress disorder 1 month after the accident. Significant differences were evident between high and low cortisol sub-groups. Those who had low cortisol level on admission and received hydrocortisone had worse outcomes.

CONCLUSION

Steroid treatment of patients with whiplash might be harmful to those who present with low cortisol concentrations (< 9.5 μg/dL).

TRIAL REGISTRATION

Clinical Trials: Association between low cortisol levels and whiplash syndrome. Date of registration: March 18, 2014. Date the first participant was enrolled: May 10, 2014.

TRIAL REGISTRATION NUMBER

NCT02090309. URL: https://clinicaltrials.gov/ct2/show/NCT02090309 .

Post-traumatic stress disorder: a state-of-the-art review of evidence and challenges

Post-traumatic stress disorder (PTSD) is arguably the most common psychiatric disorder to arise after exposure to a traumatic event. Since its formal introduction in the DSM-III in 1980, knowledge has grown significantly regarding its causes, maintaining mechanisms and treatments. Despite this increased understanding, however, the actual definition of the disorder remains controversial. The DSM-5 and ICD-11 define the disorder differently, reflecting disagreements in the field about whether the construct of PTSD should encompass a broad array of psychological manifestations that arise after trauma or should be focused more specifically on trauma memory phenomena. This controversy over clarifying the phenotype of PTSD has limited the capacity to identify biomarkers and specific mechanisms of traumatic stress. This review provides an up-to-date outline of the current definitions of PTSD, its known prevalence and risk factors, the main models to explain the disorder, and evidence-supported treatments. A major conclusion is that, although trauma-focused cognitive behavior therapy is the best-validated treatment for PTSD, it has stagnated over recent decades, and only two-thirds of PTSD patients respond adequately to this intervention. Moreover, most people with PTSD do not access evidence-based treatment, and this situation is much worse in low- and middle-income countries. Identifying processes that can overcome these major barriers to better management of people with PTSD remains an outstanding challenge.

The Biology of Human Resilience: Opportunities for Enhancing Resilience Across the Life Span

Recent scientific and technological advances have brought us closer to being able to apply a true biopsychosocial approach to the study of resilience in humans. Decades of research have identified a range of psychosocial protective factors in the face of stress and trauma. Progress in resilience research is now advancing our understanding of the biology underlying these protective factors at multiple phenotypic levels, including stress response systems, neural circuitry function, and immune responses, in interaction with genetic factors. It is becoming clear that resilience involves active and unique biological processes that buffer the organism against the impact of stress, not simply involve a reversal of pathological mechanisms. Here, we provide an overview of recent progress in the field, highlighting key psychosocial milestones and accompanying biological changes during development, and into adulthood and old age. Continued advances in our understanding of psychological, social, and biological determinants of resilience will contribute to the development of novel interventions and help optimize the type and timing of intervention for those most at risk, resulting in a possible new framework for enhancing resilience across the life span.

Translating Molecular and Neuroendocrine Findings in Posttraumatic Stress Disorder and Resilience to Novel Therapies

Many biological systems are altered in association with posttraumatic stress disorder (PTSD) and resilience. However, there are only few approved pharmacological treatments for PTSD, and no approved medications to enhance resilience. This article provides a critical review of select neurobiological findings in PTSD and resilience, and also of pharmacologic approaches that have emerged from this work. The medications summarized involve engagement with targets in the adrenergic, hypothalamic-pituitary-adrenal axis, and neuropeptide Y systems. Other highlighted approaches involve the use of ketamine and 3,4-methylenedioxymethamphetamine-assisted psychotherapy, which recently surfaced as promising strategies for PTSD, though the neurobiological mechanisms underlying their actions, including for promoting resilience, are not yet fully understood. The former approaches fall within the broad concept of "rational pharmacotherapy," in that they attempt to directly target dysregulated systems known to be associated with posttraumatic symptoms. To the extent that use of ketamine and 3,4-methylenedioxymethamphetamine promotes symptom improvement and resilience in PTSD, this provides an opportunity for reverse translation and identification of relevant targets and mechanisms of action through careful study of biological changes resulting from these interventions. Promoting resilience in trauma-exposed individuals may involve more than pharmacologically manipulating dysregulated molecules and pathways associated with developing and sustaining PTSD symptom severity, but also producing a substantial change in mental state that increases the ability to engage with traumatic material in psychotherapy. Neurobiological examination in the context of treatment studies may yield novel targets and promote a greater understanding of mechanisms of recovery from trauma.

Early intervention with electroacupuncture prevents PTSD-like behaviors in rats through enhancing hippocampal endocannabinoid signaling

Electroacupuncture (EA) is a clinically useful physiological therapy that has been recently adopted to treat several brain disorders. However, the potential role of early EA intervention in the prevention of posttraumatic stress disorder (PTSD) as well as its potential cellular and molecular mechanism has never been investigated previously. In the present study, we used an enhanced single prolonged stress (ESPS) model to access the effects of early EA intervention on the prevention of anxiety-like and fear learning behaviors, as well as the influence of the expression of post-synaptic density protein 95 (PSD95), synaptophysin (Syn), brain derived neurotrophic factor (BDNF), diacylglycerol lipase alpha (DAGLα) and cannabinoid type 1 receptor (CB1R) in the hippocampus with or without DAGLα or CB1R knockdown by a short hairpin RNA (shRNA) in the hippocampus. Moreover, the effects of electrical stimulation with different parameters on the expression of DAGLα and CB1R in the hippocampal astrocytes were also observed. The results showed that Early EA intervention improved hippocampal synaptic plasticity and ameliorated PTSD-like behaviors and also increased expression of BDNF, DAGLα and CB1R. However, either DAGLα or CB1R knockdown by a short hairpin RNA (shRNA) eliminated the neuroprotective effects of early EA intervention. Furthermore, electrical stimulation with 2/15 Hz 1 mA elevated the expression of DAGLα and CB1R. Altogether, our findings provide new insights regarding the possibility of using early EA intervention in the prevention of PTSD, and the protective effects of EA is involving the activation of DAGLα and CB1R.

PTSD as a Public Mental Health Priority

PURPOSE OF REVIEW

This article reviews recent evidence related to public health epidemiology and intervention for traumatic stress and PTSD. Recent evidence is presented regarding incidence of traumatic stress worldwide, as well as most frequent types of traumas, indicators of the public health burden of PTSD, and prevalence, predictors, and correlates of PTSD. Public health perspectives on intervention and treatment are delineated, and innovations in both psychosocial and psychopharmacological interventions are highlighted.

RECENT FINDINGS

PTSD has been associated with substantial medical and economic burden. Recent public health preventive innovations include integrated medical/behavioral health care, acute CBT and attention interventions, modifications to CBT protocols, use of novel and augmentative psychopharmacological agents, and use of technology. Recent research regarding the scope and impact of traumatic stress, as well as prevention strategies for PTSD, have resulted in an improved understanding of its impact and more effective public health interventions.

Individual variability in behavior and functional networks predicts vulnerability using an animal model of PTSD

Only a minority of individuals experiencing trauma subsequently develop post-traumatic stress disorder (PTSD). However, whether differences in vulnerability to PTSD result from a predisposition or trauma exposure remains unclear. A major challenge in differentiating these possibilities is that clinical studies focus on individuals already exposed to trauma without pre-trauma conditions. Here, using the predator scent model of PTSD in rats and a longitudinal design, we measure pre-trauma brain-wide neural circuit functional connectivity, behavioral and corticosterone responses to trauma exposure, and post-trauma anxiety. Freezing during predator scent exposure correlates with functional connectivity in a set of neural circuits, indicating pre-existing circuit function can predispose animals to differential fearful responses to threats. Counterintuitively, rats with lower freezing show more avoidance of the predator scent, a prolonged corticosterone response, and higher anxiety long after exposure. This study provides a framework of pre-existing circuit function that determines threat responses, which might directly relate to PTSD-like behaviors.

Glucocorticoids and resilience

All organisms endure frequent challenges to homeostasis, or stressors, that require adaptation. Depending on the individual, the context, and the magnitude of stress, this active adaptation can lead to behavioral susceptibility or resilience. The latter is an under-appreciated consequence of stress, as the damaging effects of chronic stress and chronically elevated glucocorticoids have received much more attention. We suggest here that neural pathways promoting resilience are initiated at the time of stress, and that they involve glucocorticoid signaling. By focusing on the neurobiology of resilience induction and the identification of vulnerable individuals, we may be able to intervene in the future at the time of stress to promote positive adaptation.

Interventions after acute stress prevent its delayed effects on the amygdala

Stress is known to elicit contrasting patterns of plasticity in the amygdala and hippocampus. While chronic stress leads to neuronal atrophy in the rodent hippocampus, it has the opposite effect in the basolateral amygdala (BLA). Further, even a single episode of acute stress is known to elicit delayed effects in the amygdala. For example, 2 h of immobilisation stress has been shown to cause a delayed increase in dendritic spine density on BLA principal neurons 10 days later in young rats. This is paralleled by higher anxiety-like behaviour at the same delayed time point. This temporal build-up of morphological and behavioural effects 10 days later, in turn, provides a stress-free time window of intervention after exposure to acute stress. Here, we explore this possibility by specifically testing the efficacy of an anxiolytic drug in reversing the delayed effects of acute immobilisation stress. Oral gavage of diazepam 1 h after immobilisation stress prevented the increase in anxiety-like behaviour on the elevated plus-maze 10 days later. The same post-stress intervention also prevented delayed spinogenesis in the BLA 10 days after acute stress. Surprisingly, gavage of only the vehicle also had a protective effect on both the behavioural and synaptic effects of stress 10 days later. Vehicle gavage was found to trigger a significant rise in corticosterone levels that was comparable to that elicited by acute stress. This suggests that a surge in corticosterone levels, caused by the vehicle gavage 1 h after acute stress, was capable of reversing the delayed enhancing effects of stress on anxiety-like behaviour and BLA synaptic connectivity. These findings are consistent with clinical reports on the protective effects of glucocorticoids against the development of symptoms of post-traumatic stress disorder. Taken together, these results reveal strategies, targeted 1 h after stress, which can prevent the delayed effects of a brief exposure to a severe physical stressor.

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Acute immobilisation stress increases anxiety and BLA spinogenesis 10 days later.

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Oral gavage of diazepam 1 h after stress prevents both these delayed effects.

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Oral gavage of vehicle also has a similar protective effect on anxiety and spines.

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Vehicle-gavage administration leads to an increase in levels of corticosterone.

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This post-stress corticosterone surge may have prevented stress-effects 10 days later.

Inflammation and post-traumatic stress disorder

While post-traumatic stress disorder (PTSD) is currently diagnosed based solely on classic psychological and behavioral symptoms, a growing body of evidence has highlighted a link between this disorder and alterations in the immune and inflammatory systems. Epidemiological studies have demonstrated that PTSD is associated with significantly increased rates of physical comorbidities in which immune dysregulation is involved, such as metabolic syndrome, atherosclerotic cardiovascular disease, and autoimmune diseases. In line with this, a number of blood biomarker studies have reported that compared to healthy controls, individuals with PTSD exhibit significantly elevated levels of proinflammatory markers, such as interleukin-1β, interleukin-6, tumor necrosis factor-α, and C-reactive protein. Moreover, various lines of animal and human research have suggested that inflammation is not only associated with PTSD but also can play an important role in its pathogenesis and pathophysiology. In this review, we first summarize evidence suggestive of increased inflammation in PTSD. We then examine findings that suggest possible mechanisms of inflammation in this disorder in terms of two different but interrelated perspectives: putative causes of increased proinflammatory activities and potential consequences that inflammation generates. Given that there is currently a dearth of treatment options for PTSD, possibilities of new therapeutic approaches using pharmacological and non-pharmacological treatments/interventions that have anti-inflammatory effects are also discussed. Despite the increasing attention given to the inflammatory pathology of PTSD, there remains much to be elucidated, including more detailed mechanisms of inflammation, potential usefulness of inflammatory biomarkers as diagnostic and prognostic markers, and efficacy of novel treatment strategies targeting inflammation.

Attachment style moderates effects of FKBP5 polymorphisms and childhood abuse on post-traumatic stress symptoms: Results from the National Health and Resilience in Veterans Study

Objectives: To determine the main and interactive effects of four FKBP5 polymorphisms (rs9296158, rs3800373, rs1360780 and rs9470080), childhood abuse and attachment style in predicting severity of PTSD symptoms in two independent, nationally representative samples of US military veterans. Methods: Data were analysed from two independent samples of European-American US military veterans who participated in the National Health and Resilience in Veterans Study (N = 1,585 and 577 respectively). Results: Results revealed that carriage of two FKBP5 minor alleles, childhood abuse and insecure attachment style were associated with greater severity of PTSD symptoms. Gene × environment interactions were also observed, with the interaction of FKBP5 homozygous minor allele carriage and history of childhood abuse associated with greater severity of PTSD symptoms; however, these effects were fully counteracted by secure attachment style. Conclusions: Results of this study build on prior work demonstrating a gene × environment interaction between FKBP5 polymorphisms and childhood abuse in predicting risk for PTSD by suggesting that attachment style may moderate this effect. This study has implications for prevention and treatment efforts designed to promote a secure attachment style in veterans with high-risk FKBP5 genotypes and childhood abuse histories.

The physiological significance of the circadian dynamics of the HPA axis: Interplay between circadian rhythms, allostasis and stress resilience

Circadian time-keeping mechanisms preserve homeostasis by synchronizing internal physiology with predictable variations in the environment and temporally organize the activation of physiological signaling mechanisms to promote survival and optimize the allocation of energetic resources. In this paper, we highlight the importance of the robust circadian dynamics of allostatic mediators, with a focus on the hypothalamic-pituitary-adrenal (HPA) axis, for the optimal regulation of host physiology and in enabling organisms to adequately respond and adapt to physiological stressors. We review studies showing how the chronic disruption of circadian rhythms can result in the accumulation of allostatic load, which impacts the appropriate functioning of physiological systems and diminishes the resilience of internal systems to adequately respond to subsequent stressors. A careful consideration of circadian rhythm dynamics leads to a more comprehensive characterization of individual variability in allostatic load and stress resilience. Finally, we suggest that the restoration of circadian rhythms after pathological disruption can enable the re-engagement of allostatic mechanisms and re-establish stress resilience.

Understanding Resilience and Preventing and Treating PTSD

Resilience is defined as the dynamic ability to adapt successfully in the face of adversity, trauma, or significant threat. Some of the key early studies of resilience were observational studies in children. They were followed by research in adults, studies testing interventions to promote resilience in different populations, and a recent upsurge of studies on the underlying genomic and neurobiological mechanisms. Neural and molecular studies in preclinical models of resilience are also increasingly identifying active stress adaptations in resilient animals. Knowledge gained from animal and human studies of resilience can be harnessed to develop new preventive interventions to enhance resilience in at-risk populations. Further, treatment interventions focused on enhancing potentially modifiable protective factors that are consistently linked to psychological resilience can enrich currently available treatment interventions for individuals with posttraumatic stress disorder (PTSD). Translating our expanding knowledge of the neurobiology of resilience additionally promises to yield novel therapeutic strategies for treating this disabling condition. This review summarizes the vast field of resilience research spanning genomic, psychosocial, and neurobiological levels, and discusses how findings have led and can lead to new preventive and treatment interventions for PTSD.

Glucocorticoids and Hippocampal Structure and Function in PTSD

This review examines the putative link between glucocorticoid and hippocampal abnormalities in posttraumatic stress disorder (PTSD). Increased glucocorticoid receptor (GR) sensitivity in PTSD may permit enhanced negative feedback inhibition of cortisol at the pituitary, hypothalamus, or other brain regions comprising the hypothalamic-pituitary-adrenal (HPA) axis and would be expected to affect other physiological systems that are regulated by glucocorticoids. Molecular and transcriptional studies of cortisol are consistent with the hypothesis that cortisol actions may be amplified in PTSD as a result of enhanced GR sensitivity in monocytes and some brain regions, although cortisol levels themselves are unchanged and oftentimes lower than normal. Concurrently, magnetic resonance imaging studies have demonstrated that individuals with PTSD have smaller hippocampal volume than individuals without PTSD. Initial hypotheses regarding the mechanism underlying hippocampal alterations in PTSD focused on elevated glucocorticoid levels in combination with extreme stress as the primary cause, but this explanation has not been well supported in human studies. Lack of data from neuroimaging studies preclude a firm link between PTSD onset and hippocampal volume changes. Rather, the available evidence is consistent with the possibility that smaller hippocampal volume (like reduced cortisol levels and enhanced GR sensitivity) may be a vulnerability factor for developing the disorder; limitations of hippocampal-based models of PTSD are described. We further review neuroimaging studies examining hippocampal structure and function following manipulation of glucocorticoid levels and also examining changes in the hippocampus in relationship to other brain regions. Evidence that the GR may be an important therapeutic target for the treatment of PTSD, especially for functions subserved by the hippocampus, is discussed. Implications of the current review for future research are described, with an emphasis on the need to integrate findings of glucocorticoid abnormalities with functional-imaging paradigms to formulate a comprehensive model of HPA-axis functioning in PTSD.

The hypothalamic-pituitary-adrenal axis in PTSD: Pathophysiology and treatment interventions

Questions of how altered functioning of the hypothalamic pituitary adrenal (HPA) axis contribute to the development and maintenance of posttraumatic stress disorder (PTSD) have been the focus of extensive animal and human research. As a rule, results have been inconsistent across studies, likely due to a variety of confounding variables that have received inadequate attention. Important confounding factors include the effects of early life stress, biological sex, and the glucocorticoid used for interventions. In this manuscript we review: 1) the literature on identified abnormalities of HPA axis function in PTSD, both in terms of basal functioning and as part of challenge paradigms; 2) the role of HPA axis function pre- and immediately post-trauma as a risk factor for PTSD development; 3) the impact of HPA axis genes' allelic variants and epigenetic modifications on PTSD risk; 4) the contributions of HPA axis components to fear learning and extinction; and 5) therapeutic manipulations of the HPA axis to both prevent and treat PTSD, including the role of glucocorticoids as part of medication enhanced psychotherapy.

Theranostic pharmacology in PTSD: Neurobiology and timing

Recent reviews and treatment guidelines regard trauma-focused cognitive-behavior therapies as the treatments of choice for chronic post-traumatic stress disorder (PTSD). However, many patients do not engage in this treatment when it is available, drop out before completion, or do not respond. Medications remain widely used, alone and in conjunction with psychotherapy, although the limitations of traditional monoamine-based pharmacotherapy are increasingly recognized. This article will review recent developments in psychopharmacology for PTSD, with a focus on current clinical data that apply putative neurobiologic mechanisms to medication use-i.e., a theranostic approach. A theranostic approach however, also requires consideration of timing, pre, peri or post trauma in conjunction with underlying dynamic processes affecting synaptic plasticity, the HPA axis, hippocampal activation, PFC-amygdala circuitry and fear memory.

Neuroendocrinological treatment targets for posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is prevalent, disabling, and frequently becomes chronic. Despite this, only two selective serotonergic reuptake inhibitors have been approved to date for its treatment by the United States Food and Drug Administration, and treatment results are often disappointing, with a remission rate of <30%. Certain neuroendocrinological systems are currently gaining attention with respect to their use for PTSD prevention and treatment as standalone options or medication-enhanced psychotherapy due to their involvement in physiological stress reactions, memory consolidation and extinction, cognitive appraisal to stress, and attachment and resilient coping strategies, which are important in the pathogenesis of PTSD. The hypothalamic-pituitary-adrenal axis system takes the most important role in stress reactions. Hydrocortisone has been studied for the prevention of PTSD, and some meta-analyses have suggested its possible efficacy; furthermore, it has been considered both as monotherapy and as an augmentation to psychotherapy in PTSD patients, with some positive results. Glucocorticoid receptor antagonists and corticotropin-releasing factor type 1 antagonists have also been considered for clinical use in PTSD treatment. Additionally, other neuroendocrinological systems have been studied in PTSD including the use of oxytocin for PTSD prevention and augmentation to psychotherapy, allopregnanolone, and neuropeptide Y (NPY) for PTSD treatment. For now, however, these studies offer only limited evidence of efficacy, thus it is prudent to study this issue more vigorously.

Glucocorticoid-induced enhancement of extinction-from animal models to clinical trials

Extensive evidence from both animal model and human research indicates that glucocorticoid hormones are crucially involved in modulating memory performance. Glucocorticoids, which are released during stressful or emotionally arousing experiences, enhance the consolidation of new memories, including extinction memory, but reduce the retrieval of previously stored memories. These memory-modulating properties of glucocorticoids have recently received considerable interest for translational purposes because strong aversive memories lie at the core of several fear-related disorders, including post-traumatic stress disorder and phobias. Moreover, exposure-based psychological treatment of these disorders relies on successful fear extinction. In this review, we argue that glucocorticoid-based interventions facilitate fear extinction by reducing the retrieval of aversive memories and enhancing the consolidation of extinction memories. Several clinical trials have already indicated that glucocorticoids might be indeed helpful in the treatment of fear-related disorders.

The Current Evidence for Acute Stress Disorder

PURPOSE OF REVIEW

The aim of this review is to provide a summary of the current evidence pertaining to the course of acute and chronic posttraumatic stress, the diagnosis of acute stress disorder (ASD), and treatment of acute stress disorder and prevention of posttraumatic stress disorder (PTSD).

RECENT FINDINGS

Although acute stress disorder was introduced partly to predict subsequent PTSD, longitudinal studies indicate that ASD is not an accurate predictor of PTSD. Recent analytic approaches adopting latent growth mixture modeling have shown that trauma-exposed people tend to follow one of four trajectories: (a) resilient, (b) worsening, (c) recovery, and (d) chronically distressed. The complexity of the course of posttraumatic stress limits the capacity of the ASD diagnosis to predict subsequent PTSD. Current evidence indicates that the treatment of choice for ASD is trauma-focused cognitive behavior therapy, and this intervention results in reduced chronic PTSD severity. Recent attempts to limit subsequent PTSD by early provision of pharmacological interventions have been promising, especially administration of corticosterone to modulate glucocorticoid levels. Although the ASD diagnosis does not accurately predict chronic PTSD, it describes recently trauma-exposed people with severe distress. Provision of CBT in the acute phase is the best available strategy to limit subsequent PTSD.

Role of Endogenous and Exogenous Corticosterone on Behavioral and Cognitive Responses to Low-Pressure Blast Wave Exposure

The complex interactions and overlapping symptoms of comorbid post-traumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) induced by an explosive blast wave have become a focus of attention in recent years, making clinical distinction and effective intervention difficult. Because dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is thought to underlie trauma-related (psycho)pathology, we evaluated both the endogenous corticosterone response and the efficacy of exogenous hydrocortisone treatment provided shortly after blast exposure. We employed a controlled experimental blast-wave paradigm in which unanesthetized animals were exposed to visual, auditory, olfactory, and tactile effects of an explosive blast wave produced by exploding a thin copper wire. Endogenous corticosterone concentrations were evaluated at different time points (before, and 3 h, 5 h and 17 days) after blast exposure. Subsequently, the efficacy of exogenous hydrocortisone (25 mg/kg^-1 or 125 mg/kg^-1) injected intraperitoneally 1 h after exposure was compared with that of a similarly timed saline injection. Validated cognitive and behavioral tests were used to assess both PTSD and mTBI phenotypes on days 7-14 following the blast. Retrospective analysis revealed that animals demonstrating the PTSD phenotype exhibited a significantly blunted endogenous corticosterone response to the blast compared with all other groups. Moreover, a single 125 mg/kg^-1 dose of hydrocortisone administered 1 h after exposure significantly reduced the occurrence of the PTSD phenotype. Hydrocortisone treatment did not have a similar effect on the mTBI phenotype. Results of this study indicate that an inadequate corticosteroid response following blast exposure increases risk for PTSD phenotype, and corticosteroid treatment is a potential clinical intervention for attenuating PTSD. The differences in patterns of physiological and therapeutic response between PTSD and mTBI phenotypes lend credence to the retrospective behavioral and cognitive classification criteria we designed, and is in keeping with the assumption that mTBI and PTSD phenotypes may reflect distinct underlying biological and clinical profiles.

Neurotransmitter, Peptide, and Steroid Hormone Abnormalities in PTSD: Biological Endophenotypes Relevant to Treatment

PURPOSE OF REVIEW

This review summarizes neurotransmitter, peptide, and other neurohormone abnormalities associated with posttraumatic stress disorder (PTSD) and relevant to development of precision medicine therapeutics for PTSD.

RECENT FINDINGS

As the number of molecular abnormalities associated with PTSD across a variety of subpopulations continues to grow, it becomes clear that no single abnormality characterizes all individuals with PTSD. Instead, individually variable points of molecular dysfunction occur within several different stress-responsive systems that interact to produce the clinical PTSD phenotype. Future work should focus on critical interactions among the systems that influence PTSD risk, severity, chronicity, comorbidity, and response to treatment. Effort also should be directed toward development of clinical procedures by which points of molecular dysfunction within these systems can be identified in individual patients. Some molecular abnormalities are more common than others and may serve as subpopulation biological endophenotypes for targeting of currently available and novel treatments.

What Acute Stress Protocols Can Tell Us About PTSD and Stress-Related Neuropsychiatric Disorders

Posttraumatic stress disorder (PTSD), the fifth most prevalent mental disorder in the United States, is a chronic, debilitating mental illness with as yet limited options for treatment. Hallmark symptoms of PTSD include intrusive memory of trauma, avoidance of reminders of the event, hyperarousal and hypervigilance, emotional numbing, and anhedonia. PTSD is often triggered by exposure to a single traumatic experience, such as a traffic accident, a natural catastrophe, or an episode of violence. This suggests that stressful events have a primary role in the pathogenesis of the disorder, although genetic background and previous life events are likely involved. However, pathophysiology of this mental disorder, as for major depression and anxiety disorders, is still poorly understood. In particular, it is unknown how can a single traumatic, stressful event induce a disease that can last for years or decades. A major shift in the conceptual framework investigating neuropsychiatric disorders has occurred in recent years, from a monoamine-oriented hypothesis (which dominated pharmacological research for over half a century) to a neuroplasticity hypothesis, which posits that structural and functional changes in brain circuitry (largely in the glutamate system) mediate psychopathology and also therapeutic action. Rodent stress models are very useful to understand pathophysiology of PTSD. Recent studies with acute or subacute stress models have shown that exposure to short-time stressors (from several minutes to a few hours) can induce not only rapid, but also sustained changes in synaptic function (glutamate release, synaptic transmission/plasticity), neuroarchitecture (dendritic morphology, synaptic spines), and behavior (cognitive functions). Some of these changes, e.g., stress-induced increased glutamate release and dendrite retraction, are likely connected and occur more rapidly than previously thought. We propose here to use a modified version of a simple and validated protocol of footshock stress to explore different trajectories in the individual response to acute stress. This new conceptual framework may enable us to identify determinants of resilient versus vulnerable response as well as new targets for treatment, in particular for rapid-acting antidepressants. It will be interesting to investigate the putative prophylactic action of ketamine toward the maladaptive effects of acute stress in this new protocol.

On the Developmental Timing of Stress: Delineating Sex-Specific Effects of Stress across Development on Adult Behavior

Stress, and the chronic overactivation of major stress hormones, is associated with several neuropsychiatric disorders. However, clinical literature on the exact role of stress either as a causative, triggering, or modulatory factor to mental illness remains unclear. We suggest that the impact of stress on the brain and behavior is heavily dependent on the developmental timing at which the stress has occurred, and as such, this may contribute to the overall variability reported on the association of stress and mental illness. Here, animal models provide a way to comprehensively assess the temporal impact of stress on behavior in a controlled manner. This review particularly focuses on the long-term impact of stress on behavior in various rodent stress models at three major developmental time points: early life, adolescence, and adulthood. We characterize the various stressor paradigms into physical, social, and pharmacological, and discuss commonalities and differences observed across these various stress-inducing methods. In addition, we discuss here how sex can influence the impact of stress at various developmental time points. We conclude here that early postnatal life and adolescence represent particular periods of vulnerability, but that stress exposure during early life can sometimes lead to resilience, particularly to fear-potentiated memories. In the adult brain, while shorter periods of stress tended to enhance spatial memory, longer periods caused impairments. Overall, males tended to be more vulnerable to the long-term effects of early life and adolescent stress, albeit very few studies incorporate both sexes, and further well-powered sex comparisons are needed.

Redefining neuroendocrinology: Epigenetics of brain-body communication over the life course

The brain is the central organ of stress and adaptation to stress that perceives and determines what is threatening, as well as the behavioral and physiological responses to the stressor, and it does so somewhat differently in males and females. The expression of steroid hormone receptors throughout the brain has broadened the definition of 'neuroendocrinology' to include the reciprocal communication between the entire brain and body via hormonal and neural pathways. Mediated in part via systemic hormonal influences, the adult and developing brain possess remarkable structural and functional plasticity in response to stress, including neuronal replacement, dendritic remodeling, and synapse turnover. This article is both an account of an emerging field elucidating brain-body interactions at multiple levels, from molecules to social organization, as well as a personal account of my laboratory's role and, most importantly, the roles of trainees and colleagues, along with my involvement in interdisciplinary groups working on this topic.

Expression of the PPM1F Gene Is Regulated by Stress and Associated With Anxiety and Depression

BACKGROUND

Molecular mechanisms underlying psychological sequelae of exposure to stressful experiences, such as posttraumatic stress disorder (PTSD) and depression, are not well understood.

METHODS

Using convergent evidence from animal and human transcriptomic and genomic studies, we aimed to identify genetic mechanisms underlying depression and anxiety after traumatic experiences.

RESULTS

From a transcriptome-wide analysis in mice, we found the Ppm1f gene to be differentially expressed in the amygdala and medial prefrontal cortex (mPFC) a week after immobilization stress. Next, we found that PPM1F messenger RNA levels in human blood were downregulated in cases with symptoms of comorbid PTSD and depression and consistently in cases with anxiety symptoms in a separate human dataset. Furthermore, we showed that a genetic variant of PPM1F, rs17759843, was associated with comorbid PTSD and depression and with PPM1F expression in both human brain and blood. Given prior reported mechanistic links between PPM1F and CAMK2 (CAMKII), we examined blood messenger RNA level of CAMK2G in humans and found it to be lower in cases with comorbid PTSD and depression. We also found that PPM1F protein levels and colocalization with CAMK2G were altered in amygdala and mPFC of male mice. Additionally, we found that a systemic dose of corticosterone blocked the depressive-like phenotype elicited by stress in female mice. Lastly, corticosterone rescued the anxiety-like phenotype and messenger RNA levels of Ppm1f in amygdala and mPFC in male mice and in mPFC of female mice.

CONCLUSIONS

Taken together, our data suggest a mechanistic pathway involving PPM1F and CAMK2G in stress- and trauma-related manifestation of anxiety and depression across species.

Integrating Endocannabinoid Signaling and Cannabinoids into the Biology and Treatment of Posttraumatic Stress Disorder

Exposure to stress is an undeniable, but in most cases surmountable, part of life. However, in certain individuals, exposure to severe or cumulative stressors can lead to an array of pathological conditions including posttraumatic stress disorder (PTSD), characterized by debilitating trauma-related intrusive thoughts, avoidance behaviors, hyperarousal, as well as depressed mood and anxiety. In the context of the rapidly changing political and legal landscape surrounding use of cannabis products in the USA, there has been a surge of public and research interest in the role of cannabinoids in the regulation of stress-related biological processes and in their potential therapeutic application for stress-related psychopathology. Here we review the current state of knowledge regarding the effects of cannabis and cannabinoids in PTSD and the preclinical and clinical literature on the effects of cannabinoids and endogenous cannabinoid signaling systems in the regulation of biological processes related to the pathogenesis of PTSD. Potential therapeutic implications of the reviewed literature are also discussed. Finally, we propose that a state of endocannabinoid deficiency could represent a stress susceptibility endophenotype predisposing to the development of trauma-related psychopathology and provide biologically plausible support for the self-medication hypotheses used to explain high rates of cannabis use in patients with trauma-related disorders.

Blunted basal corticosterone pulsatility predicts post-exposure susceptibility to PTSD phenotype in rats

The basal activity of the hypothalamic-pituitary-adrenal axis is highly dynamic and is characterized by both circadian and ultradian (pulsatile) patterns of hormone secretion. Pulsatility of glucocorticoids has been determined to be critical for optimal transcriptional, neuroendocrine, and behavioral responses. We used an animal model of post-traumatic stress disorder (PTSD) to assess whether stress-induced impairment of behavioral responses is correlated with aberrant secretion of corticosterone. Serial blood samples were collected manually via the jugular vein cannula during the light-(inactive)-phase in conscious male rats at 20-min intervals for a period of 5h before and 6.5h after exposure to predator scent stress. The outcome measures included behavior in an elevated plus-maze and acoustic startle response 7days after exposure. Individual animals were retrospectively classified as having "extreme", "partial", or "minimal" behavioral responses according to pre-set cut-off criteria for behavioral response patterns. Corticosterone secretion patterns were analyzed retrospectively. Under basal conditions, the amplitude of ultradian oscillations of corticosterone levels, rather than the mean corticosterone level or the frequency of corticosterone pulsatility, was significantly reduced in individuals who displayed PTSD-phenotype 8days later. In addition, extreme disruption of behavior on day 8 post-exposure was also characterized by a blunting of corticosterone response to the stressor. Animals with behavior that was only partially affected or unaffected displayed none of the above changes. Blunted basal corticosterone pulse amplitude is a pre-existing susceptibility or risk factor for PTSD, which originates from prior (life) experiences and may therefore predict post-exposure PTSD-phenotype in rats.

Intensive Care Unit Delirium and Intensive Care Unit-Related Posttraumatic Stress Disorder

Delirium is one of the most common behavioral manifestations of acute brain dysfunction in the intensive care unit (ICU) and is a strong predictor of worse outcome. Routine monitoring for delirium is recommended for all ICU patients using validated tools. In delirious patients, a search for all reversible precipitants is the first line of action and pharmacologic treatment should be considered when all causes have been ruled out, and it is not contraindicated. Long-term morbidity has significant consequences for survivors of critical illness and for their caregivers. ICU patients may develop posttraumatic stress disorder related to their critical illness experience.

Genomic and epigenomic mechanisms of glucocorticoids in the brain

Following the discovery of glucocorticoid receptors in the hippocampus and other brain regions, research has focused on understanding the effects of glucocorticoids in the brain and their role in regulating emotion and cognition. Glucocorticoids are essential for adaptation to stressors (allostasis) and in maladaptation resulting from allostatic load and overload. Allostatic overload, which can occur during chronic stress, can reshape the hypothalamic-pituitary-adrenal axis through epigenetic modification of genes in the hippocampus, hypothalamus and other stress-responsive brain regions. Glucocorticoids exert their effects on the brain through genomic mechanisms that involve both glucocorticoid receptors and mineralocorticoid receptors directly binding to DNA, as well as by non-genomic mechanisms. Furthermore, glucocorticoids synergize both genomically and non-genomically with neurotransmitters, neurotrophic factors, sex hormones and other stress mediators to shape an organism's present and future responses to a stressful environment. Here, we discuss the mechanisms of glucocorticoid action in the brain and review how glucocorticoids interact with stress mediators in the context of allostasis, allostatic load and stress-induced neuroplasticity.

Synaptic Loss and the Pathophysiology of PTSD: Implications for Ketamine as a Prototype Novel Therapeutic

PURPOSE OF REVIEW

Studies of the neurobiology and treatment of PTSD have highlighted many aspects of the pathophysiology of this disorder that might be relevant to treatment. The purpose of this review is to highlight the potential clinical importance of an often-neglected consequence of stress models in animals that may be relevant to PTSD: the stress-related loss of synaptic connectivity.

RECENT FINDINGS

Here, we will briefly review evidence that PTSD might be a "synaptic disconnection syndrome" and highlight the importance of this perspective for the emerging therapeutic application of ketamine as a potential rapid-acting treatment for this disorder that may work, in part, by restoring synaptic connectivity. Synaptic disconnection may contribute to the profile of PTSD symptoms that may be targeted by novel pharmacotherapeutics.

Intranasal Oxytocin to Prevent Posttraumatic Stress Disorder Symptoms: A Randomized Controlled Trial in Emergency Department Patients

BACKGROUND

There are currently few preventive interventions available for posttraumatic stress disorder (PTSD). Intranasal oxytocin administration early after trauma may prevent PTSD, because oxytocin administration was previously found to beneficially impact PTSD vulnerability factors, including neural fear responsiveness, peripheral stress reactivity, and socioemotional functioning. Therefore, we investigated the effects of intranasal oxytocin administration early after trauma on subsequent clinician-rated PTSD symptoms. We then assessed whether baseline characteristics moderated the intervention's effects.

METHODS

We performed a multicenter, randomized, double-blind, placebo-controlled clinical trial. Adult emergency department patients with moderate to severe acute distress (n = 120; 85% accident victims) were randomized to intranasal oxytocin (8 days/40 IU twice daily) or placebo (8 days/10 puffs twice daily), initiated within 12 days posttrauma. The Clinician-Administered PTSD Scale (CAPS) was administered at baseline (within 10 days posttrauma) and at 1.5, 3, and 6 months posttrauma. The intention-to-treat sample included 107 participants (oxytocin: n = 53; placebo: n = 54).

RESULTS

We did not observe a significant group difference in CAPS total score at 1.5 months posttrauma (primary outcome) or across follow-up (secondary outcome). Secondary analyses showed that participants with high baseline CAPS scores receiving oxytocin had significantly lower CAPS scores across follow-up than participants with high baseline CAPS scores receiving placebo.

CONCLUSIONS

Oxytocin administration early after trauma did not attenuate clinician-rated PTSD symptoms in all trauma-exposed participants with acute distress. However, participants with high acute clinician-rated PTSD symptom severity did show beneficial effects of oxytocin. Although replication is warranted, these findings suggest that oxytocin administration is a promising preventive intervention for PTSD for individuals with high acute PTSD symptoms.

Altered Pituitary Gland Structure and Function in Posttraumatic Stress Disorder

OBJECTIVES

Posttraumatic stress disorder (PTSD) is associated with hypothalamus-pituitary-adrenal (HPA) axis response to stressors, but links to neurophysiological and neuroanatomical changes are unclear. The purpose of this study was to determine whether stress-induced cortisol alters negative feedback on pituitary corticotroph function and pituitary volume.

DESIGN

Prospective controlled study in an outpatient clinic.

METHODS

Subjects with PTSD and matched control subjects underwent pituitary volume measurement on magnetic resonance imaging, with pituitary function assessed by 24-hour urine free cortisol (UFC), 8:00 am cortisol, and adrenocorticotropic hormone (ACTH) levels, and ACTH levels after 2-day dexamethasone/corticotropin-releasing hormone test. Primary outcome was pituitary volume; secondary outcomes were ACTH area under the curve (AUC) and 24-hour UFC.

RESULTS

Thirty-nine subjects were screened and 10 subjects with PTSD were matched with 10 healthy control subjects by sex and age. Mean pituitary volume was 729.7 mm3 [standard deviation (SD), 227.3 mm3] in PTSD subjects vs 835.2 mm3 (SD, 302.8 mm3) in control subjects. ACTH AUC was 262.5 pg/mL (SD, 133.3 pg/mL) L in PTSD vs 244.0 pg/mL (SD, 158.3 pg/mL) in control subjects (P = 0.80). In PTSD subjects, UFC levels and pituitary volume inversely correlated with PTSD duration; pituitary volume correlated with ACTH AUC in control subjects (Pearson correlation coefficient, 0.88, P = 0.0009) but not in PTSD subjects.

CONCLUSIONS

The HPA axis may be downregulated and dysregulated in people with PTSD, as demonstrated by discordant pituitary corticotroph function and pituitary volume vs intact HPA feedback and correlation of pituitary volume with ACTH levels in healthy control subjects. The results suggest a link between pituitary structure and function in PTSD, which may point to endocrine targeted therapeutic approaches.

Neurobiological and Systemic Effects of Chronic Stress

The brain is the central organ of stress and adaptation to stress because it perceives and determines what is threatening, as well as the behavioral and physiological responses to the stressor, which promote adaptation ("allostasis") but also contribute to pathophysiology ("allostatic load/overload") when overused and dysregulated. The adult as well as developing brain possesses a remarkable ability to show structural and functional plasticity in response to stressful and other experiences, including neuronal replacement, dendritic remodeling and synapse turnover. Stress can cause an imbalance of neural circuitry subserving cognition, decision making, anxiety and mood that can increase or decrease expression of those behaviors and behavioral states. This imbalance, in turn, affects systemic physiology via neuroendocrine, autonomic, immune and metabolic mediators. In the short term, these changes may be adaptive; but, if the threat passes and the behavioral state persists along with the changes in neural circuitry, such maladaptation requires intervention with a combination of pharmacological and behavioral therapies. There are important sex differences in how the brain responds to stressors. Moreover, adverse early life experience, interacting with alleles of certain genes, produces lasting effects on brain and body via epigenetic mechanisms. While prevention is key, the plasticity of the brain gives hope for therapies that utilize brain-body interactions. Policies of government and the private sector are important to promote health and increase "healthspan."