Establishing an agenda for translational research on PTSD

High-field MRI reveals an acute impact on brain function in survivors of the magnitude 8.0 earthquake in China

Besides the enormous medical and economic consequences, national disasters, such as the Wenchuan 8.0 earthquake, also pose a risk to the mental health of survivors. In this context, a better understanding is needed of how functional brain systems adapt to severe emotional stress. Previous animal studies have demonstrated the importance of limbic, paralimbic, striatal, and prefrontal structures in stress and fear responses. Human studies, which have focused primarily on patients with clinically established posttraumatic stress disorders, have reported abnormalities in similar brain structures. At present, little is known about potential alterations of brain function in trauma survivors shortly after traumatic events. Here, we show alteration of brain function in a cohort of healthy survivors within 25 days after the Wenchuan earthquake by a recently discovered method known as "resting-state" functional MRI. The current investigation demonstrates that regional activity in frontolimbic and striatal areas increased significantly and connectivity among limbic and striatal networks was attenuated in our participants who had recently experienced severe emotional trauma. Trauma victims also had a reduced temporal synchronization within the "default mode" of resting-state brain function, which has been characterized in humans and other species. Taken together, our findings provide evidence that significant alterations in brain function, similar in many ways to those observed in posttraumatic stress disorders, can be seen shortly after major traumatic experiences, highlighting the need for early evaluation and intervention for trauma survivors.

MicroRNAs in mental health: from biological underpinnings to potential therapies

Psychiatric illnesses are disabling disorders with poorly understood underlying pathophysiologies. However, it is becoming increasingly evident that these illnesses result from disruptions across whole cellular networks rather than any particular monoamine system. Recent evidence continues to support the hypothesis that these illnesses arise from impairments in cellular plasticity cascades, which lead to aberrant information processing in the circuits that regulate mood, cognition, and neurovegetative functions (sleep, appetite, energy, etc.). As a result, many have begun to consider future therapies that would be capable of affecting global changes in cellular plasticity to restore appropriate synaptic function and neuronal connectivity. MicroRNAs (miRNAs) are non-coding RNAs that can repress the gene translation of hundreds of their targets and are therefore well-positioned to target a multitude of cellular mechanisms. Here, we review some properties of miRNAs and show they are altered by stress, glucocorticoids, mood stabilizers, and in a particular psychiatric disorder, schizophrenia. While this field is still in its infancy, we consider their potential for regulating behavioral phenotypes and targeting key predicted signaling cascades that are implicated in psychiatric illness. Clearly, considerable research is required to better determine any therapeutic potential of targeting miRNAs; however, these agents may provide the next generation of effective therapies for psychiatric illnesses.

Psychological and biological correlates of fatigue after mild-to-moderate traumatic brain injury

Relationships between chronic perceived stress, cortisol response (area under the curve) and posttraumatic brain injury fatigue were examined with persons from outpatient settings. Seventy-five injured persons with traumatic brain injury and their relatives/significant others participated in this cross-sectional study. Using interviews and self-reported data from the Neurofunctional Behavioral Inventory, the Perceived Stress Scale, the Profile of Mood States-Fatigue subscale, the McGill Pain Scale, as well as self-collection of salivary cortisol over a 12-hour period (N = 50), we found that perceived chronic stress explained 40% of the variance in fatigue until depressive symptoms and pain were in the model. Hypocortisolemia was evident. Somatic symptom frequency and perceived chronic stress represented 50% of the variability in post-TBI fatigue. Fatigue and stress management interventions, as suggested in the Centers for Disease Control Acute Concussion guidelines, may be beneficial in reducing this common symptom.

Diurnal cortisol amplitude and fronto-limbic activity in response to stressful stimuli

The development and exacerbation of many psychiatric and neurologic conditions are associated with dysregulation of the hypothalamic pituitary adrenal (HPA) axis as measured by aberrant levels of cortisol secretion. Here we report on the relationship between the amplitude of diurnal cortisol secretion, measured across 3 typical days in 18 healthy individuals, and blood oxygen level dependant (BOLD) response in limbic fear/stress circuits, elicited by in-scanner presentation of emotionally negative stimuli, specifically, images of the World Trade Center (WTC) attack. Results indicate that subjects who secrete a greater amplitude of cortisol diurnally demonstrate less brain activation in limbic regions, including the amygdala and hippocampus/parahippocampus, and hypothalamus during exposure to traumatic WTC-related images. Such initial findings can begin to link our understanding, in humans, of the relationship between the diurnal amplitude of a hormone integral to the stress response, and those neuroanatomical regions that are implicated as both modulating and being modulated by that response.

Involvement of thyroid hormones in the alterations of T-cell immunity and tumor progression induced by chronic stress

BACKGROUND

Stress alters the neuroendocrine system, immunity, and cancer. Although the classic stress hormones are glucocorticoids and catecholamines, thyroid hormones have also been related to stress. We recently reported that chronic restraint stress impairs T-cell mediated immunity and enhances tumor growth in mice.

METHODS

To study the participation of these hormones on the stress-induced alterations of the immune function and lymphoma growth, mice were subjected to acute or chronic stress, with or without thyroxin supplementation. Hormone levels, immune status, and cancer progression were evaluated.

RESULTS

Differential endocrine alterations were observed in response to acute and chronic stress. Although corticosterone and noradrenaline levels were increased by acute stress, they were restored after prolonged exposure to the stressor. Instead, thyroid hormone levels were only reduced in chronically stressed animals in comparison with control subjects. Correlating, chronic but not acute stress impaired T-cell reactivity. Thyroxin replacement treatment of chronic restraint stress-exposed mice, which restored the euthyroid status, reversed the observed reduction of T-cell lymphoproliferative responses. Moreover, therapeutic thyroid replacement also reversed the alterations of lymphoma growth induced by chronic stress in syngeneic mice bearing tumors as well as Interleukin-2 production and specific cytotoxic response against tumor cells. Finally, we found that the isoforms theta and alpha of the protein kinase C are involved in these events.

CONCLUSIONS

These results show for the first time that thyroid hormones are important neuroendocrine regulators of tumor evolution, most probably acting through the modulation of T-cell mediated immunity affected by chronic stress.

Preclinical assessment for selectively disrupting a traumatic memory via postretrieval inhibition of glucocorticoid receptors

BACKGROUND

Traumatic experiences may lead to debilitating psychiatric disorders including acute stress disorder and posttraumatic stress disorder. Current treatments for these conditions are largely ineffective, and novel therapies are needed. A cardinal symptom of these pathologies is the reexperiencing of the trauma through intrusive memories and nightmares. Studies in animal models indicate that memories can be weakened by interfering with the postretrieval restabilization process known as memory reconsolidation. We previously reported that, in rats, intraamygdala injection of the glucocorticoid receptor antagonist RU38486 disrupts the reconsolidation of a traumatic memory. Here we tested parameters important for designing novel clinical protocols targeting the reconsolidation of a traumatic memory with RU38486.

METHODS

Using rat inhibitory avoidance, we tested the efficacy of postretrieval systemic administration of RU38486 on subsequent memory retention and evaluated several key preclinical parameters.

RESULTS

Systemic administration of RU38486 before or after retrieval persistently weakens inhibitory avoidance memory retention in a dose-dependent manner, and memory does not reemerge following a footshock reminder. The efficacy of treatment is a function of the intensity of the initial trauma, and intense traumatic memories can be disrupted by changing the time and number of interventions. Furthermore, one or two treatments are sufficient to disrupt the memory maximally. The treatment selectively targets the reactivated memory without interfering with the retention of another nonreactivated memory.

CONCLUSIONS

RU38486 is a potential novel treatment for psychiatric disorders linked to traumatic memories. Our data provide the parameters for designing promising clinical trials for the treatment of flashback-type symptoms of PTSD.

Functional Status, Chronic Stress, and Cortisol Response After Mild-to-Moderate Traumatic Brain Injury

It is well known that individuals experience difficulties with depressive symptoms and functional status after traumatic brain injury. However, it is unclear what the relationship is between these 2 phenomena and whether there is a biological explanation for. In this secondary analysis, we examined whether depressive symptoms explained postinjury functional status and whether chronic stress and salivary cortisol influenced this relationship. Participants included 75 persons within 24 months of their injury dates who were evaluated or treated in specialty clinics. All participants and a family member or significant other completed survey data, and 50 of the participants provided cortisol data. Results indicated that chronic stress, measured using Cohen's Perceived Stress Scale, completely mediated the relationship between depressive symptoms, measured using the Center for Epidemiological Studies Depression Scale, and psychological functioning, measured using the Patient Competency Rating Scale. Furthermore, those who provided cortisol data displayed hypocortisolemia in their 12-hr profile. Results from this analysis suggest that interventions focused on addressing the chronic stress experience may be important in limiting depressive symptoms and improving psychological functioning. Longitudinal study of this phenomenon is required to understand the progression of chronic stress after traumatic brain injury.

A deficit of brain dystrophin impairs specific amygdala GABAergic transmission and enhances defensive behaviour in mice

Duchenne muscular dystrophy (DMD) is accompanied by cognitive deficits and psychiatric symptoms. In the brain, dystrophin, the protein responsible for DMD, is localized to a subset of GABAergic synapses, but its role in brain function has not fully been addressed. Here, we report that defensive behaviour, a response to danger or a threat, is enhanced in dystrophin-deficient mdx mice. Mdx mice consistently showed potent defensive freezing responses to a brief restraint that never induced such responses in wild-type mice. Unconditioned and conditioned defensive responses to electrical footshock were also enhanced in mdx mice. No outstanding abnormality was evident in the performances of mdx mice in the elevated plus maze test, suggesting that the anxiety state is not altered in mdx mice. We found that, in mdx mice, dystrophin is expressed in the amygdala, and that, in the basolateral nucleus (BLA), the numbers of GABA(A) receptor alpha2 subunit clusters are reduced. In BLA pyramidal neurons, the frequency of norepinephrine-induced GABAergic inhibitory synaptic currents was reduced markedly in mdx mice. Morpholino oligonucleotide-induced expression of truncated dystrophin in the brains of mdx mice, but not in the muscle, ameliorated the abnormal freezing response to restraint. These results suggest that a deficit of brain dystrophin induces an alteration of amygdala local inhibitory neuronal circuits and enhancement of fear-motivated defensive behaviours in mice.

Lasting changes in social behavior and amygdala function following traumatic experience induced by a single series of foot-shocks

Neuronal plasticity within the amygdala mediates many behavioral effects of traumatic experience, and this brain region also controls various aspects of social behavior. However, the specific involvement of the amygdala in trauma-induced social deficits has never been systematically investigated. We exposed rats to a single series of electric foot-shocks--a frequently used model of trauma--and studied their behavior in the social avoidance and psychosocial stimulation tests (non-contact versions of the social interaction test) at different time intervals. Social interaction-induced neuronal activation patterns were studied in the prefrontal cortex (orbitofrontal and medial), amygdala (central, medial, and basolateral), dorsal raphe and locus coeruleus. Shock exposure markedly inhibited social behavior in both tests. The effect lasted at least 4 weeks, and amplified over time. As shown by c-Fos immunocytochemistry, social interactions activated all the investigated brain areas. Traumatic experience exacerbated this activation in the central and basolateral amygdala, but not in other regions. The tight correlation between the social deficit and amygdala activation patterns suggest that the two phenomena were associated. A real-time PCR study showed that CRF mRNA expression in the amygdala was temporarily reduced 14, but not 1 and 28 days after shock exposure. In contrast, amygdalar NK1 receptor mRNA expression increased throughout. Thus, the trauma-induced social deficits appear to be associated with, and possibly caused by, plastic changes in fear-related amygdala subdivisions.

Narrative exposure therapy for the treatment of traumatized children and adolescents (KidNET): from neurocognitive theory to field intervention

Many children in war-affected and refugee populations have experienced multiple traumatic experiences, and high rates of psychologic disorders, especially posttraumatic stress disorder (PTSD), are found. Intervention strategies require pragmatic and effective approaches to treatment. This article describes the rationale for and the use of narrative exposure therapy in children (KidNET). KidNET is a short-term treatment for PTSD based on a neurocognitive theory of traumatic memory. Early treatment trials, including randomized controlled studies, show promising results for the treatment of children and adolescents who have PTSD living in war-affected countries and refugee communities.

Gene-environment interaction in posttraumatic stress disorder: review, strategy and new directions for future research

The purpose of this article is to encourage research investigating the role of measured gene-environment interaction (G x E) in the etiology of posttraumatic stress disorder (PTSD). PTSD is uniquely suited to the study of G x E as the diagnosis requires exposure to a potentially-traumatic life event. PTSD is also moderately heritable; however, the role of genetic factors in PTSD etiology has been largely neglected both by trauma researchers and psychiatric geneticists. First, we summarize evidence for genetic influences on PTSD from family, twin, and molecular genetic studies. Second, we discuss the key challenges in G x E studies of PTSD and offer practical strategies for addressing these challenges and for discovering replicable G x E for PTSD. Finally, we propose some promising new directions for PTSD G x E research. We suggest that G x E research in PTSD is essential to understanding vulnerability and resilience following exposure to a traumatic event.

Response variation following trauma: a translational neuroscience approach to understanding PTSD

Exposure to traumatic stress is a requirement for the development of posttraumatic stress disorder (PTSD). However, because the majority of trauma-exposed persons do not develop PTSD, examination of the typical effects of a stressor will not identify the critical components of PTSD risk or pathogenesis. Rather, PTSD represents a specific phenotype associated with a failure to recover from the normal effects of trauma. Thus, research must focus on identifying pre- and posttraumatic risk factors that explain the development of the disorder and the failure to reinstate physiological homeostasis. In this review, we summarize what is known about the clinical and biological characteristics of PTSD and articulate some of the gaps in knowledge that can be addressed by basic neuroscience research. We emphasize how knowledge about individual differences related to genetic and epigenetic factors in behavioral and brain responses to stress offers the hope of a deeper understanding of PTSD.

IL-1beta is an essential mediator of the antineurogenic and anhedonic effects of stress

Stress decreases neurogenesis in the adult hippocampus, and blockade of this effect is required for the actions of antidepressants in behavioral models of depression. However, the mechanisms underlying these effects of stress have not been identified. Here, we demonstrate an essential role for the proinflammatory cytokine IL-1beta. Administration of IL-1beta or acute stress suppressed hippocampal cell proliferation. Blockade of the IL-1beta receptor, IL-1RI, by using either an inhibitor or IL-1RI null mice blocks the antineurogenic effect of stress and blocks the anhedonic behavior caused by chronic stress exposure. In vivo and in vitro studies demonstrate that hippocampal neural progenitor cells express IL-1RI and that activation of this receptor decreases cell proliferation via the nuclear factor-kappaB signaling pathway. These findings demonstrate that IL-1beta is a critical mediator of the antineurogenic and depressive-like behavior caused by acute and chronic stress.

Persistent disruption of a traumatic memory by postretrieval inactivation of glucocorticoid receptors in the amygdala

BACKGROUND

Posttraumatic stress disorder (PTSD) is characterized by acute and chronic changes in the stress response, which include alterations in glucocorticoid secretion and critically involve the limbic system, in particular the amygdala. Important symptoms of PTSD manifest as a classical conditioning to fear, which recurs each time trauma-related cues remind the subject of the original insult. Traumatic memories based on fear conditioning can be disrupted if interfering events or pharmacological interventions are applied following their retrieval.

METHODS AND RESULTS

Using an animal model, here we show that a traumatic memory is persistently disrupted if immediately after its retrieval glucocorticoid receptors are inactivated in the amygdala. The disruption of the memory is long lasting and memory retention does not re-emerge following strong reminders of the conditioned fear.

CONCLUSIONS

We propose that a combinatorial approach of psychological and pharmacological intervention targeting the glucocorticoid system following memory retrieval may represent a novel direction for the treatment of PTSD.

Resilience and aging

This article summarizes the literature on resilience to stress and aging. Key concepts and definitions of resilience are identified, and psychosocial and biological factors contributing to resilience that are universal across ages, as well as those that are unique to aging, are reviewed. Current and potentially useful intervention approaches to promote resilience and wellbeing are also reviewed. Views on future directions in resilience research and interventions targeting resilience are offered.