Generalization of Extinguished Fear to Untreated Fear Stimuli after Exposure

Generalization of beneficial exposure effects to untreated stimuli from another fear category

Previous research has shown that fear associated with one stimulus often spreads to other stimuli with similar perceptual features as well as across different stimulus categories. Exposure is considered as the most effective intervention to attenuate exaggerated fear. The extent to which exposure treatment effects can generalize to fears not targeted during treatment remains elusive. Previous studies on possible generalization of beneficial effects of exposure used stimuli sharing the same stimulus category and/or stimuli having high perceptual similarity. The current study examined whether exposure treatment generalization can be achieved for untreated stimuli which do not share any perceptual resemblance and belong to a different fear category. An analogue sample of fifty participants with fear of spiders (animal-related fears) and heights (natural environment-related fears) was tested. Participants have been randomly assigned to either an exposure treatment (n = 24) or a control condition (n = 26). Exposure treatment was designed to only target participants' fear of spiders, leaving their fear of heights untreated. Results demonstrated that the effects of exposure treatment generalized to fear of heights, as indicated by a reduction in behavioral avoidance, as well as self-reported acrophobia symptoms. The present study confutes the assumption that generalization of exposure effects to untreated fears is based on perceptual similarity. Clearly, further research is required to determine the decisive factors, in order to expand the generalization effect permanently to any given type of fear.

Conscious knowledge of CS-UCS contingency information affects extinction retrieval of conditioned disgust responses: Findings from an online de novo disgust conditioning task

Objective

The present study aimed to establish and develop an online de novo conditioning paradigm for the measurement of conditioned disgust responses. We further explored the effects of explicit instructions about the CS-UCS contingency on extinction learning and retrieval of conditioned disgust responses.

Method

The study included a sample of 115 healthy participants. Geometric figures served as conditioned stimuli (CS) and disgust-evoking pictures as unconditioned stimuli (UCS). During disgust conditioning, the CS+ was paired with the UCS (66% reinforcement) and the CS- remained unpaired; during extinction and retrieval, no UCS was presented. Half of the participants (n = 54) received instructions prior to the disgust extinction stating that the UCS will not be presented anymore. 1-2 days or 7-8 days later participants performed a retrieval test. CS-UCS contingency, disgust and valence ratings were used as dependent measures.

Results

Successful acquisition of conditioned disgust response was observed on the level of CS-UCS contingency, disgust and valence ratings. While some decline in valence and disgust ratings during the extinction stage was observed, contingency instructions did not significantly affect extinction performance. Retrieval one week later revealed that contingency instructions increased the discrimination of the CSs.

Conclusions

Extinction of conditioned disgust responses is not affected by explicit knowledge of the CS-UCS contingencies. However, contingency instructions prior to extinction seem to have a detrimental effect on long-term extinction retrieval.

Generalized extinction of fear memory depends on co-allocation of synaptic plasticity in dendrites

Memories can be modified by new experience in a specific or generalized manner. Changes in synaptic connections are crucial for memory storage, but it remains unknown how synaptic changes associated with different memories are distributed within neuronal circuits and how such distributions affect specific or generalized modification by novel experience. Here we show that fear conditioning with two different auditory stimuli (CS) and footshocks (US) induces dendritic spine elimination mainly on different dendritic branches of layer 5 pyramidal neurons in the mouse motor cortex. Subsequent fear extinction causes CS-specific spine formation and extinction of freezing behavior. In contrast, spine elimination induced by fear conditioning with >2 different CS-USs often co-exists on the same dendritic branches. Fear extinction induces CS-nonspecific spine formation and generalized fear extinction. Moreover, activation of somatostatin-expressing interneurons increases the occurrence of spine elimination induced by different CS-USs on the same dendritic branches and facilitates the generalization of fear extinction. These findings suggest that specific or generalized modification of existing memories by new experience depends on whether synaptic changes induced by previous experiences are segregated or co-exist at the level of individual dendritic branches.

The relative efficacy and efficiency of single- and multi-session exposure therapies for specific phobia: A meta-analysis

Exposure therapy is the preferred treatment for specific phobia (SP), with evidence supporting its efficacy whether delivered over multiple sessions or as a single session, such as One-Session Treatment. In this meta-analysis, we compared the efficiency and effectiveness of single- and multi-session exposure for SP. PsycINFO, Embase, MEDLINE, and Cochrane were systematically searched for peer-reviewed articles reporting the effects of multi-session (k = 30) and/or single-session (k = 55) in vivo exposure on SP symptoms in clinical populations (n = 1758 participants). A random-effects model was used to synthesise and compare the pre-post treatment effects (Hedges' g) on approach behaviour and self-reported SP symptoms. Mean total treatment time was significantly longer for multi-session exposure than for single-session. There were no significant differences in the pooled effect sizes of single-session and multi-session exposure at post-treatment and follow-up assessments; effect sizes were large for all outcomes. Phobia subtype significantly moderated the effect size for both treatment approaches, although the direction of association differed according to the outcome measures. Results suggest no evidence for differences in the effectiveness of single- and multi-session exposure, but single-session is more time efficient. These outcomes suggest that policies to facilitate access to single-session exposure would be beneficial.

A new path to mental disorders: Through gap junction channels and hemichannels

Behavioral disturbances related to emotional regulation, reward processing, cognition, sleep-wake regulation and activity/movement represent core symptoms of most common mental disorders. Increasing empirical and theoretical evidence suggests that normal functioning of these behavioral domains relies on fine graded coordination of neural and glial networks which are maintained and modulated by intercellular gap junction channels and unapposed pannexin or connexin hemichannels. Dysfunctions in these networks might contribute to the development and maintenance of psychopathological and neurobiological features associated with mental disorders. Here we review and discuss the evidence indicating a prominent role of gap junction channel and hemichannel dysfunction in core symptoms of mental disorders. We further discuss how the increasing knowledge on intercellular gap junction channels and unapposed pannexin or connexin hemichannels in the brain might lead to deeper mechanistic insight in common mental disorders and to the development of novel treatment approaches. We further attempt to exemplify what type of future research on this topic could be integrated into multidimensional approaches to understand and cure mental disorders.

Conceptual generalisation in fear conditioning using single and multiple category exemplars as conditional stimuli - electrodermal responses and valence evaluations generalise to the broader category

Conceptual generalisation occurs when conditional responses generalise to novel stimuli from the same category. Past research demonstrates that physiological fear responses generalise across categories, however, conceptual generalisation of stimulus valence evaluations during fear conditioning has not been examined. We investigated whether conceptual generalisation, as indexed by electrodermal responses and stimulus evaluations, would occur, and differ after training with single or multiple conditional stimuli (CSs). Stimuli from two of four categories (vegetables, farm animals, clothing, and office supplies) were used as the CS+ (followed by an electric stimulus) or CS- (presented alone). Generalisation was assessed by presenting novel stimuli from the CS categories after acquisition, extinction, and reinstatement. One category exemplar was used as the CS+ and CS- in the single group, whereas three exemplars were used as the CS+ and CS- in the multiple group. Electrodermal responses generalised in acquisition and extinction but did not differ between groups. In the multiple group, CS evaluations generalised in acquisition and extinction, whereas generalisation was not evident in the single group. Training with multiple CSs also resulted in the extinction of stimulus valence. The current findings have implications for future research examining the generalisation of valence and for exposure-based treatments of anxiety.

Transfer of exposure therapy effects to a threat context not considered during treatment in patients with panic disorder and agoraphobia: Implications for potential mechanisms of change

Further developments of exposure-based therapy (EBT) require more knowledge about transfer of treatment to non-trained everyday contexts. However, little is known about transfer effects of EBT. Using a standardized EBT protocol in 275 patients with panic disorder and agoraphobia we investigated the transfer of EBT to a highly standardized context during a Behavioral Avoidance Test (BAT; being entrapped in a small and dark test chamber) and not part of the exposure sessions. Patients of a treatment group underwent the BATs before treatment (t1), after a preparatory treatment phase (t2), and after an agoraphobic exposure phase (t3) and were compared with wait-list control patients, who repeated BAT assessments across the same time period. We found stronger reductions in avoidance behavior, reported fear, and autonomic arousal during the BAT from t1 to t3 in the treatment group patients who were anxious during t1 relative to the anxious but untreated patients. Fear reduction was related to treatment outcome indicating the contribution of transfer effects to successful EBT. Interestingly, reduction varied for different fear response systems suggesting different processes to may be involved in transfer effects. Importantly, final BAT assessment still evoked residual fear in the treatment group as compared to BAT non-anxious control patients, suggesting limited transfer effects - one possible reason for the return of symptoms in new situations.

Generalization of extinction with a generalization stimulus is determined by learnt threat beliefs

Expectancy violation refers to the mismatch between an expected and the actual outcome. Maximizing expectancy violation is crucial for exposure-based treatment. Since the original stimulus of fear acquisition (CS+) is rarely available, stimuli that resemble the CS+ (generalization stimuli; GSs) are presented during treatment. A given GS may evoke either strong or weak generalized fear depending on an individual's threat beliefs. Presenting this GS in extinction would then evoke different levels of expectancy violation, which determines the strength of the subsequent generalization of extinction to other stimuli, including the CS+. After differential fear conditioning, participants exhibited discrete generalization gradients depending on their inferred relational rules (Linear vs Similarity). Crucially, the Linear group showed strong generalized fear to the GS used in extinction. This strong expectancy violation led to enhanced extinction learning and subsequently to strong generalization of extinction as characterized by a flat generalization gradient, and reduced conditioned fear to the CS+. In contrast, the Similarity group showed weak generalized fear to the same GS in extinction, and limited generalization of extinction. These results corroborate the importance of expectancy violation in exposure-based treatment, and suggest that exposure sessions designed to evoke strong threat beliefs may lead to better treatment outcome.

Neural correlates of conceptual-level fear generalization in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) may develop when mechanisms for making accurate distinctions about threat relevance have gone awry. Generalization across conceptually related objects has been hypothesized based on clinical observation in PTSD, but the neural mechanisms remain unexplored. Recent trauma-exposed military veterans (n = 46) were grouped into PTSD (n = 23) and non-PTSD (n = 23). Participants learned to generalize fear across conceptual categories (animals or tools) of semantically related items that were partially reinforced by shock during functional magnetic resonance imaging. Conditioned fear learning was quantified by shock expectancy and skin conductance response (SCR). Relative to veteran controls, PTSD subjects exhibited a stronger neural response associated with fear generalization to the reinforced object category in the striatum, anterior cingulate cortex, amygdala, occipitotemporal cortex, and insula (Z > 2.3; p < 0.05; whole-brain corrected). Based on SCR, both groups generalized the shock contingency to the reinforced conceptual category, but learning was not significantly different between groups. We found that PTSD was associated with an enhanced neural response in fronto-limbic, midline, and occipitotemporal regions to a learned representation of threat that is based on previously established conceptual knowledge of the relationship between basic-level exemplars within a semantic category. Behaviorally, veterans with PTSD were somewhat slower to differentiate threat and safety categories as compared with trauma-exposed veteran controls owing in part to an initial overgeneralized behavioral response to the safe category. These results have implications for understanding how fear spreads across semantically related concepts in PTSD.

The association between fear extinction, the ability to accomplish exposure and exposure therapy outcome in specific phobia

Great interest exists in maximizing exposure therapy efficacy in anxiety disorders. At the same time, reduced frequency and shortened duration of exposure sessions are required to meet the specific regularities in routine care settings. Extinction has emerged as the key mechanism of exposure treatment in anxiety disorders. Examining exposure treatment processes from the perspective of extinction learning might provide novel insights into variability in exposure treatment duration and outcome. The present study sought to examine the functional link between fear extinction, the ability to accomplish exposure in a predetermined time and exposure therapy outcome in specific phobia. Treatment-seeking individuals (N = 53) with spider phobia underwent a context-dependent fear conditioning paradigm prior to a standardized exposure. Spider-phobic participants who were able to complete exposure within the pre-determined time (i.e., completers) showed a more pronounced short- and long-term exposure therapy benefit. In the fear conditioning task, a more pronounced decline in CS-US contingency ratings during extinction (retrieval) was found in completers relative to non-completers. The failure to further extinguish US expectancy to the CSs in non-completers might offer a potential mechanistic explanation why non-completers have difficulties to accomplish all exposure steps in a fixed time and show less pronounced treatment gains. Our findings bear specific implications for the implementation of exposure treatment to routine care settings.

No pills, more skills: The adverse effect of hormonal contraceptive use on exposure therapy benefit

Hormonal contraceptive use can aggravate existing symptoms of anxiety and depression and influence the response to pharmacologic treatment. The impact of hormonal contraceptive use on non-pharmacological treatment efficacy in anxiety disorders is less well explored. Oral contraceptives, which suppress endogenous sex hormone secretion, can alter fear extinction learning. Fear extinction is considered the laboratory proxy of exposure therapy in anxiety disorders. This study set out to examine whether oral contraceptive use is related to exposure-based treatment response in specific phobia. We recruited spider-phobic women (n = 28) using oral contraceptives (OC) and free-cycling women (n =26, No-OC). All participants were subjected to an identical in-vivo exposure. Exposure-based symptom improvement was assessed with several behavioral and subjective indices at pre-treatment, post-treatment and six-weeks follow-up. No-OC women showed higher pre-exposure fear levels on the FSQ and SPQ. OC women showed slightly less pronounced exposure benefit compared to their free-cycling counterparts (No-OC woman) as reflected by lower levels of fear reduction from pre-treatment to follow-up on the subjective level. After correction for multiple testing, OC and No-OC women showed differences in self-report measures (SPQ, FAS and SBQ) from pre- to follow-up treatment but not from pre-to post-treatment. These findings implicate that oral contraceptive use can account for differential exposure-based fear symptom improvement. Our study highlights the importance of monitoring and managing hormonal contraceptives use in the context of non-pharmacological exposure-based interventions.

Secondary extinction reduces reinstatement of threat expectancy and conditioned skin conductance responses in human fear conditioning

BACKGROUND AND OBJECTIVES

Secondary extinction refers to the phenomenon that extinction of one conditioned stimulus (CS) results in the reduction of conditioned responses for other CSs conditioned with the same unconditioned stimulus (US). Previous research with rats has demonstrated that secondary extinction can interfere with the return of conditioned fear after a reinstatement manipulation. Here we investigated this phenomenon in two pre-registered studies in humans.

METHOD

In both experiments, distinct CSs were paired with an electrical stimulation. Next, conditioned reactions to both CSs were extinguished and thereafter reinstated through the administration of three unsignaled electrical stimulations. Crucially, before participants continued with the reinstatement test, half of the participants received secondary extinction trials whereas the other half did not receive these trials.

RESULTS

Our results indicate that secondary extinction reduced reinstatement of threat expectancies and skin conductance responses, but the effect on skin conductance was only found in the second experiment.

LIMITATIONS

The studies were conducted in a laboratory setting with healthy students. Additional research will be required to determine the feasibility of applying secondary extinction in a (sub)clinical context.

CONCLUSIONS

To our knowledge, this is the first demonstration of secondary extinction and its effect on reinstatement of conditioned fear in humans. We relate our findings to the earlier research with rats and discuss their relevance for exposure therapy.

Post-exposure cortisol administration does not augment the success of exposure therapy: A randomized placebo-controlled study

Cortisol administration prior to treatment can promote the efficacy of exposure-based treatments in specific phobia: cortisol has been proposed to reduce fear retrieval at the beginning of exposure and to enhance the acquisition and consolidation of corrective information learned during exposure. Whether cortisol exerts a beneficial therapeutic effect when given after exposure, e.g., by targeting the consolidation of new corrective information, has not been addressed so far to date. Here, we examined whether post-exposure cortisol administration promotes fear reduction and reduces return of fear following contextual change in specific phobia. Furthermore, the effect of cortisol on return of fear following contextual change (i.e., contextual renewal) was assessed. Patients with spider phobia (N = 43) were treated with a single session of in-vivo exposure, followed by cortisol administration (20 mg hydrocortisone) in a double-blind, placebo-controlled study design. Return of fear was assessed with behavioral approach tests (BATs) in the familiar therapy context (versus a novel unfamiliar context) at one-month and seven-month follow-up assessment. Exposure was effective in reducing fear from pre-treatment to post-treatment (i.e., 24 h after exposure) on fear-related behavioral (approach behavior during the BAT), psychophysiological (heart rate during the BAT) and subjective (fear during the BAT, spider-fear related questionnaires) measures of therapeutic outcome, with no add-on benefit of cortisol administration. Cortisol had no effect on contextual renewal at one-month follow-up. However, in a subsample (N = 21) that returned to the seven-month follow-up, an adverse effect of cortisol on fear renewal was found, with cortisol-treated patients showing an increase in subjective fear at the final approach distance of the BAT from post-treatment to seven-month follow-up. These and previous findings underline the importance of considering the exact timing of cortisol application when used as an add-on treatment for extinction-based psychotherapy: post-exposure cortisol administration does not seem to be effective, but might promote fear renewal at the subjective level.

Learning to actively cope with stress in female mice

Repeated exposure to a same-sex resident stranger enhances subsequent indications of active coping that generalize across multiple contexts in intruder male mice. Here we investigate female mice for comparable learning to cope training effects. Stress coping research focused on females is important because stress related mood and anxiety disorders are more prevalent in women than men. Female mice were monitored for coping behavior in open-field, object-exploration, and tail-suspension tests conducted after repeated exposure to a same-sex resident stranger. During repeated exposure sessions of training staged in the resident's home cage, behavioral measures of aggression and risk assessment were collected and plasma measures of the stress hormone corticosterone were obtained from separate samples of mice. Repeated exposure to a same-sex resident stranger subsequently enhanced active coping behavior exemplified by diminished freezing and increased center entries in the open-field, shorter object-exploration latencies, and a tendency toward decreased immobility on tail-suspension tests. Open-field locomotion considered as an index of non-specific activity was not increased by repeated sessions of exposure and did not correlate significantly with any measure of active coping. During repeated sessions of exposure to a same-sex resident stranger, risk assessment behavior and consistent but limited aggression occurred and corticosterone responses increased over repeated sessions. Exposure to a same-sex resident stranger is mildly stressful and promotes learning to actively cope in mice assessed in three different contexts.

Bridging the Gaps Between Basic Science and Cognitive-Behavioral Treatments for Anxiety Disorders in Routine Care

Abstract. As a core component of cognitive-behavioral therapies (CBT), behavioral exposure is an effective treatment for anxiety disorders. Still, recent treatment studies demonstrate relatively high rates of treatment dropout, nonresponse, and relapse, indicating a substantial need for optimizing and personalizing existing treatment procedures. In the present article, we aim to address current challenges and future demands for translational research in CBT for the anxiety disorders, including (a) a better understanding of those mechanisms conferring behavioral change, (b) identifying important sources of individual variation that may act as moderators of treatment response, and (c) targeting practical barriers for dissemination of exposure therapy to routine care. Based on a recursive process model of psychotherapy research we will describe distinct steps to systematically translate basic and clinical research “from bench to bedside” to routine care, but also vice versa. Some of these aspects may stimulate the future roadmap for evidence-based psychotherapy research in order to better target the treatment of anxiety disorders as one core health challenge of our time.