Trauma reactivation under the influence of propranolol: an examination of clinical predictors

A brief treatment for veterans with PTSD: an open-label case-series study

Introduction

Despite the positive outcomes observed in numerous individuals undergoing trauma-focused psychotherapy for PTSD, veterans with this condition experience notably diminished advantages from such therapeutic interventions in comparison to non-military populations.

Methods

In a preliminary study we investigated the efficacy of an innovative treatment approach in a small sample of veterans (n = 7). Recognizing that accessing and targeting trauma memory in veterans with PTSD may be more challenging compared to other patient populations, we employed unique and personalized retrieval cues that engaged multiple senses and were connected to the context of their trauma. This was followed by a session focused on memory reconsolidation, which incorporated both psychological techniques (i.e., imagery rescripting) and a pharmacological component (i.e., 40 mg of propranolol).

Results

The findings from this small-scale case series cautiously indicate that this brief intervention, typically consisting of only one or two treatment sessions, shows promise in producing significant effects on symptoms of PTSD, distress and quality of life.This is particularly noteworthy given the complex symptomatology experienced by the veterans in this study.

Conclusion

To summarize, there are grounds for optimism regarding this brief treatment of combat-related PTSD. It appears that the potential for positive outcomes is far greater than commonly believed, as demonstrated by the encouraging results of this pilot study.

A paradigm shift in the treatment of emotional memory disorders: Lessons from basic science

Experiments demonstrating post-reactivation amnesia for learned fear in animals have generated a novel and influential hypothesis on the plasticity of memory, usually referred to as memory reconsolidation. The clinical potential of pharmacologically disrupting the process of memory reconsolidation has sparked a wave of interest into whether this phenomenon can also be demonstrated in humans, and ultimately harnessed for therapeutic purposes. In this essay we outline how the work of Karim Nader and colleagues has moved the field forward from a focus on extinction learning to the prospect of disrupting memory reconsolidation. We then review some promising findings on the necessary conditions, as well as potential boundary conditions, of pharmacologically disrupting the process of memory reconsolidation obtained in our laboratory. Even though laboratory experiments in animals and humans suggest that we may be at the brink of a breakthrough in fundamentally changing emotional memories, the necessary and sufficient conditions for targeting and disrupting memory reconsolidation in clinical practice are largely unknown. There is likely no universally effective reactivation procedure for triggering the reconsolidation of clinically significant emotional memories, and the impact of subtle boundary conditions observed in basic experiments compounds this issue. Notwithstanding these challenges, the discovery of changing emotional memory through disrupting the process of memory reconsolidation has unquestionably invigorated the field.

Examining the relationship between working memory consolidation and long-term consolidation

An emerging area of research is focused on the relationship between working memory and long-term memory and the likely overlap between these processes. Of particular interest is how some information first maintained in working memory is retained for longer periods and eventually preserved in long-term memory. The process of stabilizing transient memory representations for lasting retention is referred to as consolidation in both the working memory and long-term memory literature, although these have historically been viewed as independent constructs. The present review aims to investigate the relationship between working memory consolidation and long-term memory consolidation, which both have rich, but distinct, histories. This review provides an overview of the proposed models and neural mechanisms of both types of consolidation, as well as clinical findings related to consolidation and potential approaches for the manipulation of consolidation. Finally, two hypotheses are proposed to explain the relationship between working memory consolidation and long-term memory consolidation.

Reconsolidation-based treatment for fear of public speaking: a systematic pilot study using propranolol

Pharmacological manipulation of memory reconsolidation opens up promising new avenues for anxiety disorder treatment. However, few studies have directly investigated reconsolidation-based approaches in subclinical or clinical populations, leaving optimal means of fear memory reactivation unknown. We conducted a systematic pilot study to assess whether a reconsolidation-based treatment could tackle public speaking anxiety in a subclinical sample (N = 60). As lab studies indicate that the duration of reactivation may be important for inducing reconsolidation, we investigated several speech lengths to help inform further translational efforts. Participants underwent a stress-inducing speech task composed of 3-min preparation, and from 0 to 9 min of public speaking, in 1-min increments. They then received either 40 mg of propranolol (n = 40) or placebo (n = 20), double-blind, allocated 4:2 for each speech duration. Participants performed a second speech 1 week post treatment, and were followed up with questionnaires 1- and 3 months later. Both self-reported speech distress and questionnaire measures of public speaking anxiety showed clear reductions following treatment. However, propranolol did not reliably outperform placebo, regardless of speech duration at treatment. Physiological responses (heart rate and salivary cortisol) to the public speaking task remained stable from treatment to test. These findings highlight the challenges facing the translation of laboratory research on memory reconsolidation into clinical interventions. Lack of explicit controls for factors beyond duration, such as 'prediction error', could explain these null findings, but positive results in clinical interventions are needed to demonstrate that taking such factors into account can deliver the promises of reconsolidation-based therapy.

Sex differences in fear extinction

Despite the exponential increase in fear research during the last years, few studies have included female subjects in their design. The need to include females arises from the knowledge gap of mechanistic processes underlying the behavioral and neural differences observed in fear extinction. Moreover, the exact contribution of sex and hormones in relation to learning and behavior is still largely unknown. Insights from this field could be beneficial as fear-related disorders are twice as prevalent in women compared to men. Here, we review an up-to-date summary of animal and human studies in adulthood that report sex differences in fear extinction from a structural and functional approach. Furthermore, we describe how these factors could contribute to the observed sex differences in fear extinction during normal and pathological conditions.

The surprising subtleties of changing fear memory: a challenge for translational science

Current pharmacological and psychological treatments for disorders of emotional memory only dampen the affective response while leaving the original fear memory intact. Under adverse circumstances, these original memories regain prominence, causing relapses in many patients. The (re)discovery in neuroscience that after reactivation consolidated fear memories may return to a transient labile state, requiring a process of restabilization in order to persist, offers a window of opportunity for modifying fear memories with amnestic agents. This process, known as memory reconsolidation, opens avenues for developing a revolutionary treatment for emotional memory disorders. The reconsolidation intervention challenges the dominant pharmacological and psychological models of treatment: it is only effective when the amnestic drug is given in conjunction with memory reactivation during a specific time window, and a modification of cognitive processes is a boundary condition for changing fear. Notwithstanding the dramatic effects of targeting memory reconsolidation in the laboratory (i.e. proof of principle), the greatest hurdle to overcome is that the success of the manipulation depends on subtle differences in the reactivation procedure. These experimental parameters cannot be easily controlled in clinical practice. In harnessing the clinical potential of memory reconsolidation, a heuristic for bi-directionally translating behavioural neuroscience and clinical science is proposed.

This article is part of a discussion meeting issue ‘Of mice and mental health: facilitating dialogue between basic and clinical neuroscientists’.

Voluntary exercise or systemic propranolol ameliorates stress-related maladaptive behaviors in female rats

Many people will experience at least one traumatic event in their lifetime, with up to 20% developing Post-Traumatic Stress Disorder (PTSD) or PTSD-like symptoms. In addition, the likelihood that females will develop PTSD after trauma is more than twice that of males. Despite its prevalence, current treatment strategies for trauma victims are limited and substantial portions of affected individuals remain resistant to treatment, suggesting that additional interventions are necessary. Using an animal model of traumatic stress, the present studies tested the hypothesis that either voluntary exercise and/or administration of the adrenergic beta-receptor antagonist propranolol, would ameliorate stress-related maladaptive behaviors. In Study 1 four groups of female rats were exposed to a sequence of stressors that included anesthesia, restraint, forced swim, exposure to predator scent and fear conditioning. Rats then underwent re-exposure sessions in which stress-related conditioned stimuli were presented. In addition to re-exposure, stressed rats were treated with propranolol (10 mg/kg) and/or given the opportunity to engage in voluntary wheel running intermittently for 4 weeks. Stress-associated maladaptive behavior was assessed using the elevated plus and open field mazes and fear memory tests. Cognitive ability was assessed using a novel odor recognition task. A main effect of exercise on behaviors related to anxiety and resilience was observed, but neither a main effect of propranolol nor a synergistic effect of propranolol and exercise were observed. Neither stress induction nor treatment influenced recognition memory. In contrast, in Study 2 in which the timing and dosage of propranolol (0.25-2.0 mg/kg), and the number and timing of re-exposure sessions were adjusted, propranolol produced both a reduction in anxiety-like behaviors as well as resilience to a subsequent stressor. These results are consistent with the notion that combining re-exposure therapy with additional interventions is beneficial for female trauma victims. Furthermore, the findings support the view that in pre-clinical models, voluntary exercise, which bolsters hippocampal function and propranolol, which affects amygdala-dependent memory reconsolidation and peripheral noradrenergic signaling, can ameliorate stress-related symptoms.

Noradrenergic Modulation of Fear Conditioning and Extinction

The locus coeruleus norepinephrine (LC-NE) system plays a broad role in learning and memory. Here we begin with an overview of the LC-NE system. We then consider how both direct and indirect manipulations of the LC-NE system affect cued and contextual aversive learning and memory. We propose that NE dynamically modulates Pavlovian conditioning and extinction, either promoting or impairing learning aversive processes under different levels of behavioral arousal. We suggest that under high levels of stress (e.g., during/soon after fear conditioning) the locus coeruleus (LC) promotes cued fear learning by enhancing amygdala function while simultaneously blunting prefrontal function. Under low levels of arousal, the LC promotes PFC function to promote downstream inhibition of the amygdala and foster the extinction of cued fear. Thus, LC-NE action on the medial prefrontal cortex (mPFC) might be described by an inverted-U function such that it can either enhance or hinder learning depending on arousal states. In addition, LC-NE seems to be particularly important for the acquisition, consolidation and extinction of contextual fear memories. This may be due to dense adrenoceptor expression in the hippocampus (HPC) which encodes contextual information, and the ability of NE to regulate long-term potentiation (LTP). Moreover, recent work reveals that the diversity of LC-NE functions in aversive learning and memory are mediated by functionally heterogeneous populations of LC neurons that are defined by their projection targets. Hence, LC-NE function in learning and memory is determined by projection-specific neuromodulation that accompanies various states of behavioral arousal.

Does Beta-Blockade Reduce the Risk of Depression in Patients with Isolated Severe Extracranial Injuries?

Background

Approximately half of trauma patients develop post-traumatic depression. It is suggested that beta-blockade impairs trauma memory recollection, reducing depressive symptoms. This study investigates the effect of early beta-blockade on depression following severe traumatic injuries in patients without significant brain injury.

Methods

Patients were identified by retrospectively reviewing the trauma registry at an urban university hospital between 2007 and 2011. Severe extracranial injuries were defined as extracranial injuries with Abbreviated Injury Scale score ≥3, intracranial Abbreviated Injury Scale score <3 and an Injury Severity Score ≥16. In-hospital deaths and patients prescribed antidepressant therapy ≤1 year prior to admission were excluded. Patients were stratified into groups based on pre-admission beta-blocker status. The primary outcome was post-traumatic depression, defined as receiving antidepressants ≤1 year following trauma.

Results

Five hundred and ninety-six patients met the inclusion criteria with 11.4% prescribed pre-admission beta-blockade. Patients receiving beta-blockers were significantly older (57 ± 18 vs. 42 ± 17 years, p < 0.001) with lower Glasgow Coma Scale score (12 ± 3 vs. 14 ± 2, p < 0.001). The beta-blocked cohort spent significantly longer in hospital (21 ± 20 vs. 15 ± 17 days, p < 0.01) and intensive care (4 ± 7 vs. 3 ± 5 days, p = 0.01). A forward logistic regression model was applied and predicted lack of beta-blockade to be associated with increased risk of depression (OR 2.7, 95% CI 1.1–7.2, p = 0.04). After adjusting for group differences, patients lacking beta-blockers demonstrated an increased risk of depression (AOR 3.3, 95% CI 1.2–8.6, p = 0.02).

Conclusions

Pre-admission beta-blockade is associated with a significantly reduced risk of depression following severe traumatic injury. Further investigation is needed to determine the beneficial effects of beta-blockade in these instances.

Memory Reconsolidation Interference as an Emerging Treatment for Emotional Disorders: Strengths, Limitations, Challenges, and Opportunities

Experimental research on emotional memory reconsolidation interference, or the induction of amnesia for previously established emotional memory, has a long tradition, but the potential of that research for the development of novel interventions to treat psychological disorders has been recognized only recently. Here we provide an overview of basic research and clinical studies on emotional memory reconsolidation interference. We point out specific advantages of interventions based on memory reconsolidation interference over traditional treatment for emotional disorders. We also explain how findings from basic research suggest limitations and challenges to clinical translation that may help to understand why clinical trials have met with mixed success so far and how their success can be increased. In closing, we preview new intervention approaches beyond the induction of amnesia that the phenomenon of memory reconsolidation may afford for alleviating the burden imposed by emotional memories and comment on theoretical controversies regarding the nature of memory reconsolidation.

Does reactivation trigger episodic memory change? A meta-analysis

According to the reconsolidation hypothesis, long-term memories return to a plastic state upon their reactivation, leaving them vulnerable to interference effects and requiring re-storage processes or else these memories might be permanently lost. The present study used a meta-analytic approach to critically evaluate the evidence for reactivation-induced changes in human episodic memory. Results indicated that reactivation makes episodic memories susceptible to physiological and behavioral interference. When applied shortly after reactivation, interference manipulations altered the amount of information that could be retrieved from the original learning event. This effect was more pronounced for remote memories and memories of narrative structure. Additionally, new learning following reactivation reliably increased the number of intrusions from new information into the original memory. These findings support a dynamic view of long-term memory by showing that memories can be changed long after they were acquired.

New avenues for treating emotional memory disorders: towards a reconsolidation intervention for posttraumatic stress disorder

The discovery that fear memories may change upon retrieval, a process referred to as memory reconsolidation, opened avenues to develop a revolutionary new treatment for emotional memory disorders. Reconsolidation is a two-phase process in which retrieval of a memory initiates a transient period of memory destabilization, followed by a protein synthesis-dependent restabilization phase. This reconsolidation window offers unique opportunities for amnesic agents to interfere with the process of memory restabilization, thereby weakening or even erasing the emotional expression from specific fear memories. Here we present four uncontrolled case descriptions of patients with symptoms of posttraumatic stress disorder (PTSD) who received a reconsolidation intervention. The intervention basically involves a brief reactivation of the trauma memory aimed to trigger memory destabilization, followed by the intake of one pill of 40 mg propranolol HCl (i.e. a noradrenergic beta-blocker) that should disrupt the process of memory restabilization. We present three cases who showed a steep decline of fear symptoms after only one or two intervention sessions. To illustrate that the translation from basic science to clinical practice is not self-evident, we also present a description of a noneffective intervention in a relatively complex case. Even though the reconsolidation intervention is very promising, the success of the treatment depends on whether the memory reactivation actually triggers memory reconsolidation. Obviously the uncontrolled observations described here warrant further study in placebo-controlled designs.

Revisiting propranolol and PTSD: Memory erasure or extinction enhancement?

Posttraumatic stress disorder (PTSD) has been described as the only neuropsychiatric disorder with a known cause, yet effective behavioral and pharmacotherapies remain elusive for many afflicted individuals. PTSD is characterized by heightened noradrenergic signaling, as well as a resistance to extinction learning. Research aimed at promoting more effective treatment of PTSD has focused on memory erasure (disrupting reconsolidation) and/or enhancing extinction retention through pharmacological manipulations. Propranolol, a β-adrenoceptor antagonist, has received considerable attention for its therapeutic potential in PTSD, although its impact on patients is not always effective. In this review, we briefly examine the consequences of β-noradrenergic manipulations on both reconsolidation and extinction learning in rodents and in humans. We suggest that propranolol is effective as a fear-reducing agent when paired with behavioral therapy soon after trauma when psychological stress is high, possibly preventing or dampening the later development of PTSD. In individuals who have already suffered from PTSD for a significant period of time, propranolol may be less effective at disrupting reconsolidation of strong fear memories. Also, when PTSD has already developed, chronic treatment with propranolol may be more effective than acute intervention, given that individuals with PTSD tend to experience long-term, elevated noradrenergic hyperarousal.

Reactivating addiction-related memories under propranolol to reduce craving: A pilot randomized controlled trial

BACKGROUND

The reconsolidation blocker propranolol abolishes alcohol and drug-seeking behavior in rodents and attenuates conditioned emotional responses to drug-cues in humans in experimental settings. This suggests a role for its use in the treatment of substance dependence. In this translational pilot study, we explored the feasibility and efficacy of this procedure as an adjunct treatment for addiction. We hypothesized that guided addiction-related memory reactivation under propranolol would significantly attenuate tonic craving, a central element in relapse following addiction treatment.

METHODS

Seventeen treatment-seeking adults diagnosed with substance dependence were randomized to receive double-blind propranolol (n = 9) or placebo (n = 8) on six occasions prior to reading a personalized script detailing a drug-using experience. The primary outcome measure was self-reported craving intensity.

RESULTS

After controlling for baseline craving scores, intent-to-treat analysis revealed a time by group interaction, F(1, 14) = 5.68, p = .03, η(2) = 0.29; craving was reduced in the propranolol-treated group (Cohen's d = 1.40, p < .05) but not in the placebo group (d = 0.06, n.s.).

LIMITATIONS

The usual limitations related to small sample size and the lack of a follow-up apply here.

CONCLUSION

Drug-related memory reactivation under propranolol can subsequently reduce craving among substance-dependent individuals. Considering the relapse rate among individuals treated for substance dependence, our study highlights the feasibility of, and need for, more comprehensive trials of this treatment approach.

Emotional face processing in post-traumatic stress disorder after reconsolidation impairment using propranolol: A pilot fMRI study

Individuals with post-traumatic stress disorder (PTSD) exhibit exaggerated emotional reactions to threatening stimuli, which may represent deregulated fear-conditioning, associated with long-term adaptations in the sympathetic nervous system. Within a repeated measures design, functional magnetic resonance imaging (fMRI) was employed to investigate neural responses to threat in PTSD participants (N=7), during the presentation of emotional facial expressions. Scans were separated by 6 weekly reconsolidation impairment treatment sessions, consisting of traumatic memory reactivation under the influence of propranolol. Greater activation before versus after treatment emerged in the thalamus and amygdala during fearful versus neutral face processing. Furthermore, participants showed greater activation after versus before treatment in the right anterior cingulate, during fearful relative to happy face processing. PTSD symptoms significantly improved (d=1.75), post-treatment. These preliminary results suggest that aberrant emotional responding is modulated by noradrenergic plasticity within the amygdala-prefrontal cortex circuit, a neural substrate for the pharmacological treatment of PTSD.

Sleep-dependent memory consolidation and its implications for psychiatry

Both sleep disturbance and memory impairment are very common in psychiatric disorders. Since sleep has been shown to play a role in the process of transferring newly acquired information into long-term memory, i.e., consolidation, it is important to highlight this link in the context of psychiatric disorders. Along these lines, after providing a brief overview of healthy human sleep, current neurobiological models on sleep-dependent memory consolidation and resultant opportunities to manipulate the memory consolidation process, recent findings on sleep disturbances and sleep-dependent memory consolidation in patients with insomnia, major depression, schizophrenia, and post-traumatic stress disorder are systematically reviewed. Furthermore, possible underlying neuropathologies and their implications on therapeutic strategies are discussed. This review aims at sensitizing the reader for recognizing sleep disturbances as a potential contributor to cognitive deficits in several disorders, a fact which is often overlooked up to date.

Single dose propranolol does not affect physiologic or emotional reactivity to smoking cues

BACKGROUND

Smoking cue exposure reactivates salient smoking-related memories, triggering craving to smoke, a phenomenon associated with maintenance of smoking behavior and relapse after periods of abstinence. Acute β-adrenergic blockade with propranolol reduces physiologic reactivity during subsequent recollection of traumatic events by inhibiting reconsolidation of reactivated memories in a process called memory reconsolidation blockade.

OBJECTIVE

The objective of this study is to determine whether a single dose of propranolol prior to retrieval of smoking-related memories reduces subsequent physiologic reactivity to personally salient smoking imagery scripts in current smokers.

METHODS

Fifty-four overnight-abstinent, adult smokers received a single-dose propranolol or placebo prior to reactivation of smoking-related memories in a randomized, double-blind, placebo-controlled trial and resumed smoking afterward. One week later, skin conductance (SC), heart rate (HR), left corrugator electromyogram (EMG), self-reported emotional state, and craving were assessed following script-driven imagery with neutral and personalized smoking-related scripts.

RESULTS

Smoking scripts were associated with increased physiologic activation (SC, HR, EMG), craving, and negative emotional state compared with neutral scripts. Propranolol did not moderate the effect of script type on any outcome.

CONCLUSION

Personalized smoking script-driven imagery robustly increased physiologic activation, negative emotional state, and craving, and a single dose of propranolol prior to memory reactivation did not moderate this effect.

Psychopharmacological strategies in the management of posttraumatic stress disorder (PTSD): what have we learned?

There have been significant advancements in the pharmacologic management of posttraumatic stress disorder (PTSD) in the past two decades. Multisite randomized clinical trials (RCTs) have noted the efficacy of selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNR Is) for PTSD treatment. Unfortunately, there have been no new medications approved to treat PTSD in the past 10 years. Although there have been exciting new findings in our knowledge of the neurobiology of PTSD, clinical trials testing new medications have lagged. This review summarizes recent research that builds on the unique pathophysiology of PTSD and suggests ways to move the field forward.

Noradrenergic regulation of fear and drug-associated memory reconsolidation

Emotional and traumatic experiences lead to the development of particularly strong memories that can drive neuropsychiatric disorders, such as posttraumatic stress disorder (PTSD) and drug addiction. Disruption of these memories would therefore serve as a powerful treatment option, and targeting the pathologic emotional, but not declarative, component of a memory would be ideal for clinical intervention. Research reveals that after retrieval of a consolidated memory, the memory can be destabilized, and must then be reconsolidated through synaptic plasticity to allow subsequent retrieval. Disruption of reconsolidation-related plasticity would therefore impair specific, reactivated memories. Noradrenergic signaling strengthens synaptic plasticity and is essential for encoding the emotional components of memory. Consistent with this, investigations have now revealed that noradrenergic signaling is a critical mechanism for reconsolidation of emotional memories in rodent and human models. Here, we discuss these investigations and promising clinical trials indicating that disruption of noradrenergic signaling during reconsolidation may abolish the pathologic emotional, but not declarative, component of memories allowing alleviation of neuropsychiatric disorders including PTSD and drug addiction.

Pharmacological disruption of maladaptive memory

Many psychiatric disorders are characterized by intrusive, distracting, and disturbing memories that either perpetuate the illness or hinder successful treatment. For example, posttraumatic stress disorder (PTSD) involves such strong reemergence of memories associated with a traumatic event that the individual feels like the event is happening again. Furthermore, drug addiction is characterized by compulsive use and repeated relapse that is often driven by internal memories of drug use and/or by exposure to external stimuli that were associated with drug use. Therefore, identifying pharmacological methods to weaken the strength of maladaptive memories is a major goal of research efforts aimed at finding new treatments for these disorders. The primary mechanism by which memories could be pharmacologically disrupted or altered is through manipulation of memory reconsolidation. Reconsolidation occurs when an established memory is remembered or reactivated, reentering a labile state before again being consolidated into long-term memory storage. Memories are subject to disruption during this labile state. In this chapter we will discuss the preclinical and clinical studies identifying potential pharmacological methods for disrupting the integrity of maladaptive memory to treat mental illness.

Pharmacotherapy as prophylactic treatment of post-traumatic stress disorder: a review of the literature

Post-traumatic stress disorder has a lifetime prevalence of almost 9% in the United States. The diagnosis is associated with increased rates of comorbid substance abuse and increased rates of depression. Providers are taught how to diagnose and treat PTSD, but little discussion is devoted to how to prevent the disorder. Behavioral research in animal studies has provided some evidence for the use of medications in decreasing the fear response and the reconsolidation of memories. A heightened fear response and the re-experience of traumatic memory are key components for diagnosis. The purpose of this literature review is to examine the evidence for pharmacotherapy as prophylactic treatment in acute stress/trauma in order to prevent the development of post-traumatic stress disorder. The body of the review includes discussions on medications, medications as adjunct to script-driven imagery, and special considerations for military, first responders, and women. This article concludes with implications for practice and recommendations for future research. The key words used for the literature search were "prophylactic treatment of PTSD," "pharmacotherapy and trauma," "pharmacological prevention of PTSD," "beta blockers and the prevention of PTSD," "acute stress and prevention of PTSD," "propranolol and PTSD," "secondary prevention of PTSD," and "medications used to prevent PTSD." Findings were categorized by medications and medications as adjunct to script-driven imagery. The literature suggests that hydrocortisone, propranolol, and morphine may decrease symptoms and diagnosis of post-traumatic stress disorder.

Memory as a new therapeutic target

This review aims to demonstrate how an understanding of the brain mechanisms involved in memory provides a basis for; (i) reconceptualizing some mental disorders; (ii) refining existing therapeutic tools; and (iii) designing new ones for targeting processes that maintain these disorders. First, some of the stages which a memory undergoes are defined, and the clinical relevance of an understanding of memory processing by the brain is discussed. This is followed by a brief review of some of the clinical studies that have targeted memory processes. Finally, some new insights provided by the field of neuroscience with implications for conceptualizing mental disorders are presented.

Young and old Pavlovian fear memories can be modified with extinction training during reconsolidation in humans

Extinction training during reconsolidation has been shown to persistently diminish conditioned fear responses across species. We investigated in humans if older fear memories can benefit similarly. Using a Pavlovian fear conditioning paradigm we compared standard extinction and extinction after memory reactivation 1 d or 7 d following acquisition. Participants who underwent extinction during reconsolidation showed no evidence of fear recovery, whereas fear responses returned in participants who underwent standard extinction. We observed this effect in young and old fear memories. Extending the beneficial use of reconsolidation to older fear memories in humans is promising for therapeutic applications.

Treatment of pediatric anxiety disorders

This article provides a brief review of the current available data concerning present treatment and potential new treatment advances for pediatric anxiety disorders, such as generalized anxiety disorder, separation anxiety disorder, social phobia, obsessive-compulsive disorder, and posttraumatic stress disorder. Disorder-specific treatment methods and innovations, particularly computer-assisted methods of delivery for cognitive behavioral therapy (CBT) will be reviewed. Additionally, the paper will discuss novel psychopharmacological compounds (e.g., D-cycloserine, riluzole, memantine, and anticonvulsant medications). Available evidence for the efficacy of novel medication strategies in adult studies and implications for their use in pediatrics will be discussed.

Human reconsolidation: a reactivation and update

The reconsolidation hypothesis states that memories, when reactivated, enter a transient, labile state followed by a re-stabilization termed reconsolidation. By affecting the reconsolidation process, memory persistence can be influenced, leading to memory enhancement or decrement. This is a time-dependent process and the result of modulating reconsolidation is present only after the reconsolidation process is completed. Historically, reconsolidation research has been performed on non-human animals, since the methods originally used for reconsolidation disruption are not safe. However, there now exist several techniques safe for humans, and consequently, in recent years, papers on human reconsolidation have emerged. Here, the existing literature on human reconsolidation is reviewed and discussed, including studies on fear memories, appetitive memories, procedural memories, and declarative memories. Methods of memory reactivation are compared between studies, and the consistency and lack of consistency in results over reactivation methods and memory types are discussed. These results provide future challenges, both experimental and clinical, in defining the boundary conditions and mechanisms governing the reconsolidation phenomenon. This article is part of a Special Issue entitled 'Memory Enhancement'.

A possible mechanism for PTSD symptoms in patients with traumatic brain injury: central autonomic network disruption

Patients with traumatic brain injuries (TBI) often develop post traumatic stress disorder (PTSD). This syndrome, defined and diagnosed by psychological and behavioral features, is associated with symptoms such as anxiety and anger with an increase of arousal and vigilance, as well as flashbacks and nightmares. Many of these features and symptoms observed in PTSD may be in part the result of altered autonomic nervous system (ANS) activity in response to psychological and physical challenges. Brain imaging has documented that TBI often induces white matter damage to pathways associated with the anterior limb of the internal capsule and uncinate fasciculus. Since these white matter structures link neocortical networks with subcortical and limbic structures that regulate autonomic control centers, injury to these pathways may induce a loss of inhibitory control of the ANS. In this review, the autonomic features associated with PTSD are discussed in the context of traumatic brain injury. We posit that TBI induced damage to networks that regulate the ANS increase vulnerability to PTSD. The means by which the vulnerability can be measured and tested are also discussed.

Pain and suicidality: insights from reward and addiction neuroscience

Suicidality is exceedingly prevalent in pain patients. Although the pathophysiology of this link remains unclear, it may be potentially related to the partial congruence of physical and emotional pain systems. The latter system's role in suicide is also conspicuous during setbacks and losses sustained in the context of social attachments. Here we propose a model based on the neural pathways mediating reward and anti-reward (i.e., allostatic adjustment to recurrent activation of the reward circuitry); both are relevant etiologic factors in pain, suicide and social attachments. A comprehensive literature search on neurobiology of pain and suicidality was performed. The collected articles were critically reviewed and relevant data were extracted and summarized within four key areas: (1) physical and emotional pain, (2) emotional pain and social attachments, (3) pain- and suicide-related alterations of the reward and anti-reward circuits as compared to addiction, which is the premier probe for dysfunction of these circuits and (4) mechanistically informed treatments of co-occurring pain and suicidality. Pain-, stress- and analgesic drugs-induced opponent and proponent states of the mesolimbic dopaminergic pathways may render reward and anti-reward systems vulnerable to sensitization, cross-sensitization and aberrant learning of contents and contexts associated with suicidal acts and behaviors. These findings suggest that pain patients exhibit alterations in the brain circuits mediating reward (depressed function) and anti-reward (sensitized function) that may affect their proclivity for suicide and support pain and suicidality classification among other "reward deficiency syndromes" and a new proposal for "enhanced anti-reward syndromes". We suggest that interventions aimed at restoring the balance between the reward and anti-reward networks in patients with chronic pain may help decreasing their suicide risk.

[Prophylaxis and therapy of post-traumatic stress disorder with propranolol: evidence and ethical analysis]

The beta-antagonistic agent propranolol is increasingly being used in clinical trials for the prophylaxis and treatment of post-traumatic stress disorder (PTSD). This article discusses the evidence for the effectiveness of propranolol in the prophylaxis and treatment of PTSD and the ethical implications of research on these treatment approaches. The efficacy of a prophylactic or therapeutic use could not be shown during the last decade. Both treatment approaches raise ethical questions that should already be addressed during the clinical trials.

Memory reconsolidation in aversive and appetitive settings

Memory reconsolidation has been observed across species and in a number of behavioral paradigms. The majority of memory reconsolidation studies have been carried out in Pavlovian fear conditioning and other aversive memory settings, with potential implications for the treatment of post-traumatic stress disorder. However, there is a growing literature on memory reconsolidation in appetitive reward-related memory paradigms, including translational models of drug addiction. While there appears to be substantial similarity in the basic phenomenon and underlying mechanisms of memory reconsolidation across unconditioned stimulus valence, there are also notable discrepancies. These arise both when comparing aversive to appetitive paradigms and also across different paradigms within the same valence of memory. We review the demonstration of memory reconsolidation across different aversive and appetitive memory paradigms, the commonalities and differences in underlying mechanisms and the conditions under which each memory undergoes reconsolidation. We focus particularly on whether principles derived from the aversive literature are applicable to appetitive settings, and also whether the expanding literature in appetitive paradigms is informative for fear memory reconsolidation.

Propranolol's effects on the consolidation and reconsolidation of long-term emotional memory in healthy participants: a meta-analysis

BACKGROUND

Considering the pivotal role of negative emotional experiences in the development and persistence of mental disorders, interfering with the consolidation/reconsolidation of such experiences would open the door to a novel treatment approach in psychiatry. We conducted a meta-analysis on the experimental evidence regarding the capacity of the ß-blocker propranolol to block the consolidation/reconsolidation of emotional memories in healthy adults.

METHODS

Selected studies consisted of randomized, double-blind experiments assessing long-term memory for emotional material in healthy adults and involved at least 1 propranolol and 1 placebo condition. We searched PsycInfo, PubMed, Web of Science, Cochrane Central, PILOTS, Google Scholar and clinicaltrials.org for eligible studies from the period 1995-2012. Ten consolidation (n = 259) and 8 reconsolidation (n = 308) experiments met the inclusion criteria. We calculated effect sizes (Hedges g) using a random effects model.

RESULTS

Compared with placebo, propranolol given before memory consolidation reduced subsequent recall for negatively valenced stories, pictures and word lists (Hedges g = 0.44, 95% confidence interval [CI] 0.14-0.74). Propranolol before reconsolidation also reduced subsequent recall for negatively valenced emotional words and the expression of cue-elicited fear responses (Hedges g = 0.56, 95% CI 0.13-1.00).

LIMITATIONS

Limitations include the moderate number of studies examining the influence of propranolol on emotional memory consolidation and reconsolidation in healthy adults and the fact that most samples consisted entirely of young adults, which may limit the ecological validity of results.

CONCLUSION

Propranolol shows promise in reducing subsequent memory for new or recalled emotional material in healthy adults. However, future studies will need to investigate whether more powerful idiosyncratic emotional memories can also be weakened and whether this weakening can bring about long-lasting symptomatic relief in clinical populations, such as patients with posttraumatic stress or other event-related disorders.

Randomized controlled trial of a brief dyadic cognitive-behavioral intervention designed to prevent PTSD

BACKGROUND

There is a dearth of effective interventions to prevent the development of post-traumatic stress disorder (PTSD).

METHOD

We evaluated the efficacy of a brief dyadic two-session cognitive-behavioral intervention through a controlled trial involving trauma-exposed individuals recruited at the hospital's emergency room. Participants were randomly assigned to either the dyadic intervention group (n=37) or to a waiting list (assessment only) group (n=37).

RESULTS

In an intent-to-treat analysis, a time-by-group interaction was found, whereby the treated participants had less PTSD symptoms at the post-treatment but not at the pre-treatment compared to controls. Controlling for the improvement observed in the control participants, the intervention yielded a net effect size of d=0.39.

CONCLUSIONS

A brief, early, and effective intervention can be provided by nurses or social workers in hospital settings, at a fairly low cost to individuals presenting to the emergency room as the result of trauma exposure.

Trauma reactivation under the influence of propranolol: an examination of clinical predictors

BACKGROUND

In two recent studies conducted by our group, a treatment combining propranolol with a brief reactivation session subsequently reduced posttraumatic stress disorder (PTSD) symptom severity and diagnosis, as well as reducing psychophysiological responses during trauma-related script-driven imagery. One likely explanation for those results is that memory reconsolidation was blocked by propranolol.

OBJECTIVE

We explored the influence of various predictors on treatment outcome (i.e., PTSD severity), and whether the treated individuals improved in other important domains of functioning associated with PTSD.

METHOD

Thirty-three patients with longstanding PTSD participated in a 6-week open-label trial consisting of actively recalling one's trauma under the influence of propranolol, once a week.

RESULTS

Treated patients reported a better quality of life, less comorbid depressive symptoms, less negative emotions in their daily life and during trauma recollections. Women were also found to improve more than men. Type of trauma (childhood vs. adulthood), time elapsed since trauma, borderline personality traits, depressive symptoms severity, Axis I comorbidity, and age did not influence treatment outcome.

CONCLUSION

These results must await publication of a randomized-controlled trial to further delineate effectiveness with this novel treatment approach.