Acute effects of alcohol on the development of intrusive memories

A systematic review and meta-analysis of experimental methods for modulating intrusive memories following lab-analogue trauma exposure in non-clinical populations

Experiencing trauma leads to intrusive memories (IMs), a hallmark symptom of post-traumatic stress disorder (PTSD), which also occurs transdiagnostically. Understanding why IMs increase or decrease is pivotal in developing interventions to support mental health. In this preregistered meta-analysis (PROSPERO: CRD42021224835), we included 134 articles (131 techniques, 606 effect sizes and 12,074 non-clinical participants) to investigate how experimental techniques alter IM frequency, intrusion-related distress and symptoms arising from lab-analogue trauma exposure. Eligible articles were identified by searching eight databases until 12 December 2023. To test potential publication biases, we employed methods including Egger's test and three-parameter selection models. We employed three-level multilevel modelling and meta-regressions to examine whether and how experimental techniques would modulate IM frequency and associated outcomes. Results showed that techniques (behavioural, pharmacological, neuromodulation) significantly reduced intrusion frequency (g = 0.16, 95% confidence interval [0.09, 0.23]). Notably, techniques aimed to reduce IMs also ameliorated intrusion-related distress and symptoms, while techniques that increased IMs exacerbated these related outcomes, thus highlighting IM's centrality in PTSD-like symptoms. Techniques tapping into mental imagery processing (for example, trauma reminder followed by playing Tetris) reduced intrusions when administered immediately after, or at a delayed time after trauma. Although our meta-analysis is limited to symptoms induced by lab-analogue trauma exposure, some lab-based results have now generalized to real-world trauma and IMs, highlighting the promising utility of lab-analogue trauma paradigms for intervention development.

Ecological Momentary Assessments of Trauma-Related Intrusive Memories: Potential Clinical Utility

As the global prevalence of trauma rises, there is a growing need for accessible and scalable treatments for trauma-related disorders like posttraumatic stress disorder (PTSD). Trauma-related intrusive memories (TR-IMs) are a central PTSD symptom and a target of exposure-based therapies, gold-standard treatments that are effective but resource-intensive. This study examined whether a brief ecological momentary assessment (EMA) protocol assessing the phenomenology of TR-IMs could reduce intrusion symptoms in trauma-exposed adults. Participants (N=131) experiencing at least 2 TR-IMs per week related to a DSM-5 criterion A trauma completed a 2-week EMA protocol during which they reported on TR-IM properties three times per day, and on posttraumatic stress symptoms at the end of each day. Longitudinal symptom measurements were entered into linear mixed-effects models to test the effect of Time on TR-IMs. Over the 2-week EMA protocol, intrusion symptom severity (cluster B scores) significantly declined (t = -2.78, p = 0.006), while other symptom cluster scores did not significantly change. Follow-up analyses demonstrated that this effect was specific to TR-IMs (t = -4.02, p < 0.001), and was not moderated by survey completion rate, total PTSD symptom severity, or ongoing treatment. Our findings indicate that implementing an EMA protocol assessing intrusive memories could be an effective trauma intervention. Despite study limitations like its quasi-experimental design and absence of a control group, the specificity of findings to intrusive memories argues against a mere regression to the mean. Overall, an EMA approach could provide a cost-effective and scalable treatment option targeting intrusive memory symptoms.

Integrating and fragmenting memories under stress and alcohol

Stress can powerfully influence the way we form memories, particularly the extent to which they are integrated or situated within an underlying spatiotemporal and broader knowledge architecture. These different representations in turn have significant consequences for the way we use these memories to guide later behavior. Puzzlingly, although stress has historically been argued to promote fragmentation, leading to disjoint memory representations, more recent work suggests that stress can also facilitate memory binding and integration. Understanding the circumstances under which stress fosters integration will be key to resolving this discrepancy and unpacking the mechanisms by which stress can shape later behavior. Here, we examine memory integration at multiple levels: linking together the content of an individual experience, threading associations between related but distinct events, and binding an experience into a pre-existing schema or sense of causal structure. We discuss neural and cognitive mechanisms underlying each form of integration as well as findings regarding how stress, aversive learning, and negative affect can modulate each. In this analysis, we uncover that stress can indeed promote each level of integration. We also show how memory integration may apply to understanding effects of alcohol, highlighting extant clinical and preclinical findings and opportunities for further investigation. Finally, we consider the implications of integration and fragmentation for later memory-guided behavior, and the importance of understanding which type of memory representation is potentiated in order to design appropriate interventions.

The impact of post-encoding alcohol consumption on episodic memory recall and remember-know responses in heavy drinkers

Introduction

People often consume alcohol following trauma, particularly in response to distressing memories. To date, little is known about how post-encoding alcohol consumption influences episodic memory recall for negative events. Understanding these effects may help to improve support for trauma victims - for example, witnesses and victims of crimes.

Methods

We tested 60 participants who self-described as heavy drinkers. After watching an analog trauma film, half were allocated to consuming a moderate dose of alcohol (Alcohol-Exposed group), while half received a placebo drink (Placebo-Control group). Immediately and after a one-week delay, participants recalled the event via free and cued recall tasks. Participants also gave remember-know responses and confidence ratings, elucidating alcohol's effect on experiential memory.

Results

Free recall performance was similar for the Alcohol-Exposed group and the Placebo-Control group during Sessions 1 and 2. The Alcohol-Exposed group benefitted more from the delayed repeated retrieval attempt. For the cued recall task, the Alcohol-Exposed group provided more "Do not Know" responses compared to the Placebo-Control group in both sessions. For the Alcohol-Exposed group only "Correct Know" responses increased from Session 1 to 2. Although memory performance improved across sessions, confidence levels decreased from Session 1 to 2 in the Alcohol-Exposed group.

Discussion

Post-encoding alcohol consumption appears to impact immediate episodic memory retrieval; however, this effect is only temporary in nature. No evidence was found that alcohol primarily reduces remembering responses. Much like previous findings focusing on pre-encoding alcohol consumption (Hagsand et al., 2017), current findings suggest that providing individuals who drank alcohol after witnessing an incident with a delayed repeated retrieval attempt can lead to more complete and accurate testimonies.

Frontal alpha asymmetry in alcohol-related intimate partner violence

Electroencephalographic (EEG) frontal alpha asymmetry (FAA) has been associated with differences in the experience and expression of emotion, motivation and anger in normal and clinical populations. The current study is the first to investigate FAA in alcohol-related intimate partner violence. EEG was recorded from 23 distressed violent (DV) and 15 distressed nonviolent (DNV) partners during a placebo-controlled alcohol administration and emotion-regulation study. The State-Trait Anger Expression Inventory 2 was used to evaluate anger experiences and was collected from both participants and their partners. During baseline, acute alcohol intoxication DV partners had significantly greater right FAA, whereas DNV partners showed greater left FAA. Both partner types demonstrated significantly greater right FAA during the placebo beverage condition of the emotion-regulation task when viewing evocative partner displays of contempt, belligerence, criticism, defensiveness and stonewalling, but greater left FAA during acute alcohol intoxication. Although no group differences were found in the emotion-regulation task, partner self-reported anger experiences accounted for 67% of the variance in the FAA of DV participants when intoxicated and viewing evocative stimuli, suggesting dyadic processes are important in understanding alcohol-related IPV. These findings suggest that FAA could index the affective and motivational determinants through which alcohol is related to IPV.

Intrusive memories and voluntary memory of a trauma film: Differential effects of a cognitive interference task after encoding

Methods to reduce intrusive memories (e.g., of traumatic events) should ideally spare voluntary memory for the same event (e.g., to report on the event in court). Single-trace memory accounts assume that interfering with a trace should impact both its involuntary and voluntary expressions, whereas separate-trace accounts assume these two can dissociate, allowing for selective interference. This possibility was investigated in 3 experiments. Nonclinical participants viewed a trauma film followed by an interference task (Tetris game-play after reminder cues). Next, memory for the film was assessed with various measures. The interference task reduced the number of intrusive memories (diary-based, Experiments 1 and 2), but spared performance on well-matched measures of voluntary retrieval-free recall (Experiment 1) and recognition (Experiments 1 and 2)-challenging single-trace accounts. The interference task did not affect other measures of involuntary retrieval-perceptual priming (Experiment 1) or attentional bias (Experiment 2). However, the interference task did reduce the number of intrusive memories in a laboratory-based vigilance-intrusion task (Experiments 2 and 3), irrespective of concurrent working memory load during intrusion retrieval (Experiment 3). Collectively, results reveal a robust dissociation between intrusive and voluntary memories, having ruled out key methodological differences between how these two memory expressions are assessed, namely cue overlap (Experiment 1), attentional capture (Experiment 2), and retrieval load (Experiment 3). We argue that the inability of these retrieval factors to explain the selective interference is more compatible with separate-trace than single-trace accounts. Further theoretical developments are needed to account for this clinically important distinction between intrusive memories and their voluntary counterpart. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Observing Alcohol Myopia in the Context of a Trauma Film Paradigm: Differential Recall of Central and Peripheral Details

BACKGROUND

A major tenet of the alcohol myopia model is that intoxication results in a narrowing of attention to the most central environmental cues, at the cost of more peripheral information. Though long hypothesized, no known study of alcohol myopia has demonstrated differential immediate recall of central and peripheral cues using a standardized task. To address this gap, we conducted an alcohol administration study with a clear, standardized focus-a trauma film.

METHODS

Ninety-eight female social drinkers completed self-report measures, and then were randomized to consume a placebo beverage, a low dose of alcohol (mean breath alcohol concentration [BrAC] = 0.04%), or a high dose of alcohol (mean BrAC = 0.11%). Participants then moved to a staged room where they viewed a film clip depicting a sexual assault. After leaving the room, participants completed a written free recall task of the film and the room.

RESULTS

The distinction between recall of central and peripheral details was supported by confirmatory factor analysis. Consistent with the alcohol myopia model, relative to placebo, a high dose of alcohol led to impaired recall of peripheral (but not central) details. Although the interaction between BrAC and information type (central vs. peripheral) was not statistically significant, simple effects revealed a strong association between BrAC and peripheral information, and no association between BrAC and central information. Bolstering myopia as an explanation for our findings, neither central nor peripheral information correlated with self-reported tendencies to dissociate or distract oneself, or typical alcohol consumption or expectancies.

CONCLUSIONS

Alcohol myopia can be observed through an immediate free recall task following a stressful film. Additional research is needed to continue evaluating dose-dependent differential recall in larger samples. This task may be useful for clarifying the role of alcohol myopia in clinical phenomena, such as aggressive behavior and processing traumatic events.

Intrusive memories of trauma: A target for research bridging cognitive science and its clinical application

Intrusive memories of a traumatic event can be distressing and disruptive, and comprise a core clinical feature of post-traumatic stress disorder (PTSD). Intrusive memories involve mental imagery-based impressions that intrude into mind involuntarily, and are emotional. Here we consider how recent advances in cognitive science have fueled our understanding of the development and possible treatment of intrusive memories of trauma. We conducted a systematic literature search in PubMed, selecting articles published from 2008 to 2018 that used the terms "trauma" AND ("intrusive memories" OR "involuntary memories") in their abstract or title. First, we discuss studies that investigated internal (neural, hormonal, psychophysiological, and cognitive) processes that contribute to intrusive memory development. Second, we discuss studies that targeted these processes using behavioural/pharmacological interventions to reduce intrusive memories. Third, we consider possible clinical implications of this work and highlight some emerging research avenues for treatment and prevention, supplemented by new data to examine some unanswered questions. In conclusion, we raise the possibility that intrusive memories comprise an alternative, possibly more focused, target in translational research endeavours, rather than only targeting overall symptoms of disorders such as PTSD. If so, relatively simple approaches could help to address the need for easy-to-deliver, widely-scalable trauma interventions.

Post-traumatic Stress Disorder in Victims of Sexual Assault With Pre-assault Substance Consumption: A Systematic Review

Background: Post-traumatic stress disorder (PTSD) and substance consumption commonly co-occur in victims of sexual assault. Substance consumption can occur pre- andi/or post-assault. Pre-assault substance consumption may have an impact on the subsequent development of PTSD. This review aims to provide an overview of current understanding of the effects of acute substance intoxication and chronic pre-assault problematic substance use on symptoms of PTSD amongst individuals who were victims of sexual assault. Methods: PsycINFO, EMBASE, and MEDLINE were searched using terms related to PTSD, sexual assault, and substance consumption. These yielded 2,121 articles, 268 of which were retrieved for more detailed evaluation and 13 of these met inclusion criteria and were appraised in full. Results: Overall, the reviewed papers supported our hypothesis that acute substance intoxication and chronic pre-assault problematic substance use are associated with fewer initial PTSD symptoms but less improvement over time, resulting in slower overall PTSD recovery. They also highlighted post-assault characterological self-blame and negative social reactions as mediators of recovery in the context of pre-assault substance consumption. Conclusions: Acute substance intoxication and chronic pre-assault problematic substance use appear to have an impact on the development of PTSD symptoms amongst victims of sexual assault. The importance of developing early interventions and routine screening and assessment for PTSD and pre-assault substance consumption is emphasized. The limited research on male victims and on substances other than alcohol is highlighted.

Detail-oriented visual processing style: Its role in the relationships between early life adversity and hoarding-related dysfunctions

Early life adversity, ranging from material deprivation and parental dysfunction to abusive and life-threatening events, has been associated with hoarding symptom severity. Moreover, both victims of early life adversity and individuals with hoarding disorder have been found to have a higher tendency toward detail-oriented visual processing. This study aimed to investigate the role of detail-oriented visual processing in the relationship between early life adversity and hoarding-related dysfunction. Childhood exposure to life adversity, hoarding symptom severity, and emotional attachment to possessions, a hoarding-related dysfunction thought to be most closely related to adversity exposure, were assessed. Detail-oriented visual processing was evaluated using the Central Coherence Index, which was calculated based on the drawing process during the Rey-Osterrieth Complex Figure Test. It was found that detail-oriented visual processing was not significantly associated with hoarding symptom severity, emotional attachment to possessions, or the relationship between early life adversity and hoarding symptom severity. It did, however, act as a significant moderator in the relationship between early life adversity and emotional attachment to possessions. These findings add to the literature by identifying the role of a specific neurocognitive processing style in the mechanism through which early life adversity affects the development of a key hoarding-related dysfunction, elevated emotional attachment to possessions.

Can't get it out of my mind: A systematic review of predictors of intrusive memories of distressing events

Intrusive memories, when persistent and distressing, are theorized to underlie a range of transdiagnostic psychological symptoms and associated impairment. However, little is known about factors predicting the development and persistence of intrusive memories. The aim of this systematic review is to evaluate the literature on pre-event, event-based, and post-event predictors of intrusive memories. A systematic review was conducted, searching for studies that examined intrusive, event-based memories. One hundred and six articles were identified from PsycInfo, PubMed, and Medline databases. Experimental and prospective studies with clinical (N = 14) and nonclinical (N = 92) samples were critically reviewed, provided the inclusion of an analogue stressor with nonclinical samples, and that intrusive memories frequency and/or distress were assessed as primary dependent variables. Pre-existing psychopathology and pre-event appraisal style appear to predict intrusive memories (small to medium effects), whereas trait dissociation did not predict intrusive memories. Of studies examining event-based predictors, higher data-driven processing appears to predict intrusive memories with generally large effects. Post-event negative appraisals consistently predicted intrusive memories (medium to large effects), and preliminary evidence suggests higher post-event conceptual processing predicting fewer intrusive memories. This review synthesizes findings regarding a broad range of pre-event, event-based, and post-event factors that may influence the development of intrusive memories. Methodological issues of current paradigms and the lack of emphasis on memory retrieval processes limit our understanding of what predicts intrusive memory persistence. These limitations are particularly important given that individuals typically seek treatment for distressing intrusive memories once a memory has been fully consolidated, where retrieval processes are of utmost importance. (PsycINFO Database Record

Intrusive Memories of Trauma in the Laboratory: Methodological Developments and Future Directions

Purpose of the Review

Intrusive memories are those that spring to mind unbidden, e.g. sensory recollections of stressful/traumatic events. We review recent methods to monitor intrusions of a stressor (a trauma film) within the laboratory.

Recent Findings

Recent studies suggest three main methodologies after viewing a trauma film by which to monitor intrusions in the laboratory: during post-film rest periods, after exposure to trigger cues, and while performing an ongoing task. These approaches allow factors to be tested (e.g. psychological or pharmacological) that may influence the frequency of occurrence of intrusions.

Summary

We raise methodological considerations to guide trauma film studies using intrusion monitoring in the laboratory to complement monitoring approaches in daily life (e.g. diaries). Intrusion monitoring in the laboratory also confers greater experimental control and may open novel research avenues, to advance intervention development to mitigate problematic intrusive memory symptoms.

Victim Alcohol Intoxication During a Sexual Assault: Relations With Subsequent PTSD Symptoms

This study examines associations between women's alcohol intoxication at the time of sexual assault and posttraumatic stress disorder (PTSD) symptoms. Drawing on the dual representation theory (Brewin, Gregory, Lipton, & Burgess, 2010), we hypothesized that intoxication at the time of assault would be positively associated with both overall symptoms of PTSD and PTSD reexperiencing symptoms in particular. A total of 143 community women (ages 18-26 years; 71.3% European American) reporting sexual victimization completed questionnaires assessing severity of coercion involved in the assault, perceived level of intoxication at the time of assault, and current PTSD symptoms. Overall, results suggested that greater alcohol intoxication (but not alcohol use alone) was associated with more severe PTSD symptoms when controlling for severity of coercion. Furthermore, higher levels of victim intoxication at the time of the assault were most predictive of reexperiencing symptoms relative to the other symptom clusters.

Posttraumatic Stress and Problem Drinking at the Transition Out of College

The objective of the present study was to examine how symptoms of posttraumatic stress disorder (PTSD) may confer drinking risk as students with trauma histories complete college and move toward independent adulthood. Students (N = 283) completed assessments of trauma, posttraumatic stress, and alcohol use and consequences at four time points during the year following their fourth year of college. Some students had transitioned out of the college environment, whereas others had not. We examined how transition status moderated within-person associations between changes in PTSD and corresponding changes in alcohol outcomes over time. Using multilevel modeling, we examined differences in within-person PTSD-alcohol associations comparing students who were (1) continuing as fifth-year seniors, (2) graduated and pursuing graduate education, and (3) graduated and left the university setting. Alcohol use and consequences tended to decline on average from the fourth to fifth year post-matriculation. Yet, within-person increases in posttraumatic stress symptomatology across the fifth year were associated with greater alcohol consequences, but only for those students who had left the university setting. These data suggest that the transition out of college may be an important developmental context that is associated with increased vulnerability for negative consequences from stress-related drinking. Findings may have important implications for campus-based prevention efforts geared toward the facilitation of a successful transition into independent adulthood.

Neurobiology of comorbid post-traumatic stress disorder and alcohol-use disorder

Post-traumatic stress disorder (PTSD) and alcohol-use disorder (AUD) are highly comorbid in humans. Although we have some understanding of the structural and functional brain changes that define each of these disorders, and how those changes contribute to the behavioral symptoms that define them, little is known about the neurobiology of comorbid PTSD and AUD, which may be due in part to a scarcity of adequate animal models for examining this research question. The goal of this review is to summarize the current state-of-the-science on comorbid PTSD and AUD. We summarize epidemiological data documenting the prevalence of this comorbidity, review what is known about the potential neurobiological basis for the frequent co-occurrence of PTSD and AUD and discuss successes and failures of past and current treatment strategies. We also review animal models that aim to examine comorbid PTSD and AUD, highlighting where the models parallel the human condition, and we discuss the strengths and weaknesses of each model. We conclude by discussing key gaps in our knowledge and strategies for addressing them: in particular, we (1) highlight the need for better animal models of the comorbid condition and better clinical trial design, (2) emphasize the need for examination of subpopulation effects and individual differences and (3) urge cross-talk between basic and clinical researchers that is reflected in collaborative work with forward and reverse translational impact.

Nitrous oxide speeds the reduction of distressing intrusive memories in an experimental model of psychological trauma

BACKGROUND

Post-traumatic stress disorder (PTSD) involves maladaptive long-term memory formation which underlies involuntary intrusive thoughts about the trauma. Preventing the development of such maladaptive memory is a key aim in preventing the development of PTSD. We examined whether the N-methyl d-aspartate receptor (NMDAR) antagonist gas nitrous oxide (N2O) could reduce the frequency of intrusive memories by inhibiting NMDAR-dependent memory consolidation in a laboratory analogue of psychological trauma.

METHOD

Participants were randomized to inhale N2O (N = 25) or medical air (N = 25) after viewing a negatively valenced emotional film clip ('trauma film'). Participants subsequently completed a daily diary assessing frequency of intrusive thoughts relating to the film clip. A week later, participants completed an explicit memory recall task related to the film.

RESULTS

Post-encoding N2O sped the reduction in intrusive memory frequency, with a significant reduction by the next day in the N2O group compared to 4 days later in the air group. N2O also interacted with post-film dissociation, producing increased intrusion frequency in those who were highly dissociated at baseline. Sleep length and quality the night after viewing the film did not differ between the groups.

CONCLUSION

N2O speeds the reduction of intrusive analogue trauma memory in a time-dependent manner, consistent with sleep-dependent long-term consolidation disruption. Further research with this drug is warranted to determine its potential to inoculate against enduring effects of psychological trauma; however, caution is also urged in dissociated individuals where N2O may aggravate PTSD-like symptomatology.

PTSD symptom course during the first year of college

OBJECTIVES

In this study we examined patterns of transition in posttraumatic stress disorder (PTSD) symptoms over the 1st year of college. We also examined 2 factors that might predict these transitions: trauma exposure and alcohol involvement.

METHOD

Matriculating students (N = 944; 65% female) completed assessments of PTSD, trauma exposure, and alcohol use and consequences multiple times in their freshman year. Three symptom classes (no symptoms, moderate symptoms, and severe symptoms) were identified. Examination of transitions from 1 status to another was conducted with latent transition analysis.

RESULTS

These models revealed considerable variability in the course of PTSD symptoms. The most common pattern was resolution, yet a significant portion of students showed other patterns. Symptom worsening was more commonly observed in the 2nd semester. Trauma exposure had a deleterious effect on PTSD symptom change trajectories, as did alcohol involvement, though less consistently so.

CONCLUSIONS

Interventions that focus on the timing and correlates of symptom progression may benefit college students with posttraumatic distress. (PsycINFO Database Record

Alcohol Doesn't Always Compromise Cognitive Function: Exploring Moderate Doses in Young Adults

OBJECTIVE

The purpose of this study was to clarify inconsistent findings regarding the acute cognitive effects of subintoxicating alcohol doses (i.e., <80 mg/dl) by controlling for and evaluating variables that might modulate dose-related outcomes.

METHOD

The current study examined the effects of sex/gender and alcohol concentration on select cognitive functions in 94 individuals (49 men) between 25 and 35 years of age. Participants were randomly assigned to one of three dose conditions: target peak breath alcohol concentration of 0 mg/dl (placebo), 40 mg/dl (low), or 65 mg/dl (moderate). After beverage consumption, they completed tasks assessing psychomotor, set-shifting, and working memory ability.

RESULTS

Analyses revealed no significant effect of dose for any cognitive domain. A trend-level effect of dose on psychomotor performance was observed, with the low-dose group performing somewhat better than the moderate-dose and placebo groups. No sex main effects or interactions were revealed.

CONCLUSIONS

Consistent with our previous studies, these data suggest that low and moderate doses of alcohol may not compromise cognitive ability in non-problem drinkers under certain task conditions. Given the outcomes, sex differences cannot be meaningfully addressed. Future consideration of potentially influential variables and assessment of similarly well-defined cohorts might yield a clearer interpretation of alcohol's behavioral consequences.

Extinction learning is slower, weaker and less context specific after alcohol

Alcohol is frequently involved in psychological trauma and often used by individuals to reduce fear and anxiety. We examined the effects of alcohol on fear acquisition and extinction within a virtual environment. Healthy volunteers were administered alcohol (0.4 g/kg) or placebo and underwent acquisition and extinction from different viewpoints of a virtual courtyard, in which the conditioned stimulus, paired with a mild electric shock, was centrally located. Participants returned the following day to test fear recall from both viewpoints of the courtyard. Skin conductance responses were recorded as an index of conditioned fear. Successful fear acquisition under alcohol contrasted with impaired extinction learning evidenced by persistent conditioned responses (Experiment 1). Participants’ impairments in extinction under alcohol correlated with impairments in remembering object-locations in the courtyard seen from one viewpoint when tested from the other viewpoint. Alcohol-induced extinction impairments were overcome by increasing the number of extinction trials (Experiment 2). However, a test of fear recall the next day showed persistent fear in the alcohol group across both viewpoints. Thus, alcohol impaired extinction rather than acquisition of fear, suggesting that extinction is more dependent than acquisition on alcohol-sensitive representations of spatial context. Overall, extinction learning under alcohol was slower, weaker and less context-specific, resulting in persistent fear at test that generalized to the extinction viewpoint. The selective effect on extinction suggests an effect of alcohol on prefrontal involvement, while the reduced context-specificity implicates the hippocampus. These findings have important implications for the use of alcohol by individuals with clinical anxiety disorders.

Coping, PTSD symptoms, and alcohol involvement in trauma-exposed college students in the first three years of college

The objective of the present study was to examine prospective, bidirectional associations among posttraumatic stress disorder (PTSD) symptoms, coping style, and alcohol involvement (use, consequences) in a sample of trauma-exposed students just entering college. We also sought to test the mechanistic role that coping may play in associations between PTSD symptoms and problem alcohol involvement over time. Participants (N = 734) completed measures of trauma exposure, PTSD symptoms, coping, and alcohol use and consequences in September of their first college year and again each September for the next 2 years. We observed reciprocal associations between PTSD and negative coping strategies. In our examination of a mediated pathway through coping, we found an indirect association from alcohol consequences and PTSD symptoms via negative coping, suggesting that alcohol consequences may exacerbate posttraumatic stress over time by promoting negative coping strategies. Trauma characteristics such as type (interpersonal vs. noninterpersonal) and trauma reexposure did not moderate these pathways. Models were also invariant across gender. Findings from the present study point to risk that is conferred by both PTSD and alcohol consequences for using negative coping approaches, and through this, for posttraumatic stress. Interventions designed to decrease negative coping may help to offset this risk, leading to more positive outcomes for those students who enter college with trauma exposure.

Hypomanic Experience in Young Adults Confers Vulnerability to Intrusive Imagery After Experimental Trauma: Relevance for Bipolar Disorder

Emotional mental imagery occurs across anxiety disorders, yet is neglected in bipolar disorder despite high anxiety comorbidity. Furthermore, a heightened susceptibility to developing intrusive mental images of stressful events in bipolar disorder and people vulnerable to it (with hypomanic experience) has been suggested. The current study assessed, prospectively, whether significant hypomanic experience (contrasting groups scoring high vs. low on the Mood Disorder Questionnaire, MDQ) places individuals at increased risk of visual reexperiencing after experimental stress. A total of 110 young adults watched a trauma film and recorded film-related intrusive images for 6 days. Compared to the low MDQ group, the high MDQ group experienced approximately twice as many intrusive images, substantiated by convergent measures. Findings suggest hypomanic experience is associated with developing more frequent intrusive imagery of a stressor. Because mental imagery powerfully affects emotion, such imagery may contribute to bipolar mood instability and offer a cognitive treatment target.

Heart rate, startle response, and intrusive trauma memories

The current study adopted the trauma film paradigm to examine potential moderators affecting heart rate (HR) as an indicator of peritraumatic psychological states and as a predictor of intrusive memories. We replicated previous findings that perifilm HR decreases predicted the development of intrusive images and further showed this effect to be specific to images rather than thoughts, and to detail rather than gist recognition memory. Moreover, a group of individuals showing both an atypical sudden reduction in HR after a startle stimulus and higher trait dissociation was identified. Only among these individuals was lower perifilm HR found to indicate higher state dissociation, fear, and anxiety, along with reduced vividness of intrusions. The current findings emphasize how peritraumatic physiological responses relate to emotional reactions and intrusive memory. The moderating role of individual difference in stress defense style was highlighted.

Acute alcohol effects on attentional bias are mediated by subcortical areas associated with arousal and salience attribution

Acute alcohol ingestion increases attentional bias to alcohol-related stimuli; however, the underlying cognitive and brain mechanisms remain unknown. We combined functional magnetic resonance imaging (fMRI) with performance of a dual task that probed attentional distraction by alcohol-related stimuli during 'conflict' processing: the Concurrent Flanker/Alcohol-Attentional bias task (CFAAT). In this task, an Eriksen Flanker task is superimposed on task-unrelated background pictures with alcohol-associated or neutral content. Participants respond to the direction of a central 'target' arrow and ignore adjacent congruent (low cognitive load) or incongruent (high cognitive load) 'flanking' arrows. Using a between-subject design, 40 healthy moderate-to-heavy social drinkers received either no alcohol (placebo), 0.4 g/kg (low dose), or 0.8 g/kg (high dose) of alcohol, and underwent fMRI while performing the CFAAT. The low alcohol dose, relative to placebo, increased response latencies on trials with alcohol-associated backgrounds and, under low cognitive load, increased the activity evoked by these pictures within a medial hypothalamic region. Under high cognitive load, the low alcohol dose, relative to placebo, elicited greater activity within a more lateral hypothalamic region, and reduced activity within frontal motor areas. The high alcohol dose, relative to placebo, did not reliably affect response latencies or neural responses to background images, but reduced overall accuracy under high cognitive load. This effect correlated with changes in reactivity within medial and dorsal prefrontal cortices. These data suggest that alcohol at a low dose primes attentional bias to alcohol-associated stimuli, an effect mediated by activation of subcortical hypothalamic areas implicated in arousal and salience attribution.

Processing of facial affect in social drinkers: a dose-response study of alcohol using dynamic emotion expressions

RATIONALE

Studies of affect recognition can inform our understanding of the interpersonal effects of alcohol and help develop a more complete neuropsychological profile of this drug.

OBJECTIVES

The objective of the study was to examine affect recognition in social drinkers using a novel dynamic affect-recognition task, sampling performance across a range of evolutionarily significant target emotions and neutral expressions.

METHODS

Participants received 0, 0.4 or 0.8 g/kg alcohol in a double-blind, independent groups design. Relatively naturalistic changes in facial expression-from neutral (mouth open) to increasing intensities of target emotions, as well as neutral (mouth closed)-were simulated using computer-generated dynamic morphs. Accuracy and reaction time were measured and a two-high-threshold model applied to hits and false-alarm data to determine sensitivity and response bias.

RESULTS

While there was no effect on the principal emotion expressions (happiness, sadness, fear, anger and disgust), compared to those receiving 0.8 g/kg of alcohol and placebo, participants administered with 0.4 g/kg alcohol tended to show an enhanced response bias to neutral expressions. Exploration of this effect suggested an accompanying tendency to misattribute neutrality to sad expressions following the 0.4-g/kg dose.

CONCLUSIONS

The 0.4-g/kg alcohol-but not 0.8 g/kg-produced a limited and specific modification in affect recognition evidenced by a neutral response bias and possibly an accompanying tendency to misclassify sad expressions as neutral. In light of previous findings on involuntary negative memory following the 0.4-g/kg dose, we suggest that moderate-but not high-doses of alcohol have a special relevance to emotional processing in social drinkers.

The hippocampus and spatial constraints on mental imagery

We review a model of imagery and memory retrieval based on allocentric spatial representation by place cells and boundary vector cells (BVCs) in the medial temporal lobe, and their translation into egocentric images in retrosplenial and parietal areas. In this model, the activity of place cells constrain the contents of imagery and retrieval to be coherent and consistent with the subject occupying a single location, while the activity of head-direction cells along Papez's circuit determine the viewpoint direction for which the egocentric image is generated. An extension of this model is discussed in which a role for grid cells in dynamic updating of representations (mental navigation) is included. We also discuss the extension of this model to implement a version of the dual representation theory of post-traumatic stress disorder (PTSD) in which PTSD arises from an imbalance between weak allocentric hippocampal-mediated contextual representations and strong affective/sensory representations. The implications of these models for behavioral, neuropsychological, and neuroimaging data in humans are explored.

Alcohol Use, Problems, and the Course of Posttraumatic Stress Disorder: A Prospective Study of Female Crime Victims

OBJECTIVE

This study examines whether alcohol use disorder status and consequences of drinking moderate the course of PTSD over the first 6 months following trauma exposure in a sample of female victims of interpersonal violence.

METHODS

Female sexual and physical assault victims (n = 64) were recruited through police, hospital, and victim service agencies. Women completed structured clinical interviews and self-report measures within the first five weeks, three months, and six months post-trauma with 73% retention across all three time points (n = 47). Analyses were conducted using Hierarchical Linear Modeling using alcohol abuse/dependence, peak alcohol use, and consequences during the 30 days prior to assault as moderators of the course of PTSD over time.

RESULTS

Women with alcohol use disorder at baseline had lower initial PTSD symptoms but also less symptom recovery over time than women without alcohol use disorder. This pattern of results was also found for those with high negative drinking consequences during the month prior to the assault. Baseline alcohol use was not found to significantly moderate PTSD course over the 6 months.

CONCLUSIONS

Findings suggest that negative consequences associated with alcohol use may be a risk factor for PTSD. Incorporating assessment of drinking problems for women presenting early post-trauma may be useful for identifying PTSD risk.

Hippocampal dysfunction effects on context memory: possible etiology for posttraumatic stress disorder

Hippocampal volume reductions and functional impairments are reliable findings in posttraumatic stress disorder (PTSD) imaging studies. However, it is not clear if and how hippocampal dysfunction contributes to the etiology and maintenance of PTSD. Individuals with PTSD are often described as showing fear responses to trauma reminders outside of contexts in which these cues would reasonably predict danger. Animal studies suggest that the hippocampus is required to form and recall associations between contextual stimuli and aversive events. For example, the hippocampus is critical for encoding memories in which a complex configuration of multiple cues is associated with the aversive event. Conversely, the hippocampus is not required for associations with discrete cues. In animal studies, if configural memory is disrupted, learning strategies using discrete cue associations predominate. These data suggest poor hippocampal function could bias the organism toward forming multiple simple cue associations during trauma, thus increasing the chances of fear responses in multiple environments (or contexts) in which these cues may be present. Here we will examine clinical and preclinical literature to support a theory of hippocampal dysfunction as a primary contributory factor to the etiology of PTSD, and discuss future research required to test these hypotheses. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.

Natural memory beyond the storage model: repression, trauma, and the construction of a personal past

Naturally occurring memory processes show features which are difficult to investigate by conventional cognitive neuroscience paradigms. Distortions of memory for problematic contents are described both by psychoanalysis (internal conflicts) and research on post-traumatic stress disorder (PTSD; external traumata). Typically, declarative memory for these contents is impaired - possibly due to repression in the case of internal conflicts or due to dissociation in the case of external traumata - but they continue to exert an unconscious pathological influence: neurotic symptoms or psychosomatic disorders after repression or flashbacks and intrusions in PTSD after dissociation. Several experimental paradigms aim at investigating repression in healthy control subjects. We argue that these paradigms do not adequately operationalize the clinical process of repression, because they rely on an intentional inhibition of random stimuli (suppression). Furthermore, these paradigms ignore that memory distortions due to repression or dissociation are most accurately characterized by a lack of self-referential processing, resulting in an impaired integration of these contents into the self. This aspect of repression and dissociation cannot be captured by the concept of memory as a storage device which is usually employed in the cognitive neurosciences. It can only be assessed within the framework of a constructivist memory concept, according to which successful memory involves a reconstruction of experiences such that they fit into a representation of the self. We suggest several experimental paradigms that allow for the investigation of the neural correlates of repressed memories and trauma-induced memory distortions based on a constructivist memory concept.

Acute effects of alcohol on intrusive memory development and viewpoint dependence in spatial memory support a dual representation model

BACKGROUND

A dual representation model of intrusive memory proposes that personally experienced events give rise to two types of representation: an image-based, egocentric representation based on sensory-perceptual features; and a more abstract, allocentric representation that incorporates spatiotemporal context. The model proposes that intrusions reflect involuntary reactivation of egocentric representations in the absence of a corresponding allocentric representation. We tested the model by investigating the effect of alcohol on intrusive memories and, concurrently, on egocentric and allocentric spatial memory.

METHODS

With a double-blind independent group design participants were administered alcohol (.4 or .8 g/kg) or placebo. A virtual environment was used to present objects and test recognition memory from the same viewpoint as presentation (tapping egocentric memory) or a shifted viewpoint (tapping allocentric memory). Participants were also exposed to a trauma video and required to detail intrusive memories for 7 days, after which explicit memory was assessed.

RESULTS

There was a selective impairment of shifted-view recognition after the low dose of alcohol, whereas the high dose induced a global impairment in same-view and shifted-view conditions. Alcohol showed a dose-dependent inverted "U"-shaped effect on intrusions, with only the low dose increasing the number of intrusions, replicating previous work. When same-view recognition was intact, decrements in shifted-view recognition were associated with increases in intrusions.

CONCLUSIONS

The differential effect of alcohol on intrusive memories and on same/shifted-view recognition support a dual representation model in which intrusions might reflect an imbalance between two types of memory representation. These findings highlight important clinical implications, given alcohol's involvement in real-life trauma.

Alcohol-involved assault and the course of PTSD in female crime victims

Although alcohol use has been associated with increased risk of victimization, little is known about how victim substance use at the time of assault may affect posttraumatic stress disorder (PTSD) symptom development. The present study is a longitudinal examination of substance use on PTSD symptom severity and course. A community sample of female crime victims (n = 60) were assessed within 5 weeks of sexual or physical assault with 3 and 6 month post-assault follow-ups. Twenty-three participants had consumed alcohol or alcohol/drugs prior to the assault (38%) and 37 had consumed neither alcohol nor drugs. Analyses were conducted using hierarchical linear modeling. Participants who had consumed alcohol had lower initial intrusive symptoms, but their symptoms improved less over time.

Decreases in recollective experience following acute alcohol: a dose-response study

RATIONALE

Acute alcohol intoxication induces a selective impairment of recognition memory associated with conscious recollection whilst recognition based on familiarity is left intact.

OBJECTIVES

We aimed to further elucidate the acute effects of alcohol on recognition memory by assessing three different doses of alcohol and examining the way in which this affected the recollection and familiarity components of recognition memory in comparison to a placebo group.

METHODS

A double-blind independent design was used, and participants received either alcohol (0.4, 0.6 or 0.8 g/kg) or a placebo drink. Participants encoded word pairs with depth of processing manipulated under generate and read conditions. Recognition memory was assessed and recollective awareness was examined through use of the remember-know procedure.

RESULTS

Alcohol produced a dose-dependent reduction in recognition memory associated with recollection, evidenced by decreases in the number of correctly recognised items with 'remember' responses compared to placebo. Recognition based on a familiarity, evidenced by 'know' responses, showed no differences between groups or pattern of reduction compared to the placebo group. However, a negative correlation was found between recognition based on familiarity and levels of intoxication.

CONCLUSIONS

Alcohol-induced impairments in recognition memory occur in a dose-dependent manner, specifically driven by reductions in recognition associated with conscious awareness.