Reducing fear overgeneralization in children using a novel perceptual discrimination task

Fear generalization predicts post-traumatic stress symptoms: A two-year follow-up study in Dutch fire fighters

INTRODUCTION

Excessive fear generalization has been associated with pathological anxiety, including posttraumatic stress disorder (PTSD). However, studies investigating the longitudinal relationship between generalization and the development of anxiety symptomatology are scarce. This study aims to test the predictive value of fear generalization for PTSD symptoms in a high-risk profession sample and to explore the relationship between generalization and neuroticism, which are both linked to PTSD.

METHOD

Longitudinal data from a multi-wave study in 529 Dutch fire-fighters were used. Fear generalization, PTSD symptoms and neuroticism were assessed at baseline. PTSD symptoms were reevaluated at six, 12, 18, and 24 months. Generalization was assessed in a differential conditioning paradigm by measuring expectancies of an aversive outcome when presented with stimuli similar to previously conditioned stimuli.

RESULTS

Higher expectancy ratings towards stimuli most similar to safety signals predicted PTSD symptoms at follow-up after controlling for baseline PTSD symptoms, whereas higher expectancy ratings towards stimuli most similar to danger signals was associated with neuroticism. Neuroticism weakened the predictive power of fear generalization when considered simultaneously.

DISCUSSION

These findings suggest that heightened fear generalization is associated with the development of anxiety and trauma-related symptoms. Targeting problematic fear generalization may be a promising intervention approach.

No influence of threat uncertainty on fear generalization

Fear overgeneralization and perceived uncertainty about future outcomes have been suggested as risk factors for clinical anxiety. However, little is known regarding how they influence each other. In this study, we investigated whether different levels of threat uncertainty influence fear generalization. Three groups of healthy participants underwent a differential fear conditioning protocol followed by a generalization test. All groups learned to associate one female face (conditioned stimulus, CS+) with a female scream (unconditioned stimulus, US), whereas the other face (CS-) was not associated with the scream. In order to manipulate threat uncertainty, one group (low uncertainty, n = 26) received 80%, the second group (moderate uncertainty, n = 32) received 60%, and the third group (high uncertainty, n = 30) 40% CS-US contingency. In the generalization test, all groups saw CS+ and CS- again along with four morphs resembling the CSs in steps of 20%. Subjective (expectancy, valence, and arousal ratings), psychophysiological (skin conductance response, SCR), and visuocortical (steady-state visual evoked potentials, ssVEPs) indices of fear were registered. Participants expected the US according to their reinforcement schedules and the discriminative responses to CS+/CS- increased with more uncertainty in skin conductance. However, acquisition of conditioned fear was not evident in ssVEPs. During the generalization test, we found no effect of threat uncertainty in any of the measured variables, but the strength of generalization for threat expectancy ratings was positively correlated with dispositional intolerance of uncertainty. This study suggests that mere threat uncertainty does not modulate fear generalization.

Anxiety disorders in children and adolescents: A summary and overview of the literature

Considerable work has advanced understanding of the nature, causes, management, and prevention of anxiety disorders in children and adolescents over the past 30 years. Prior to this time the primary focus was on school refusal and specific phobias. It is now recognised that children and adolescents experience the full gamut of anxiety disorders in very similar ways to adults and that anxiety disorders in the paediatric years can predict a lifelong mental-health struggle. Given the vast array of specific studies in this field, the current review summarises current knowledge about these high prevalence disorders, points to overarching limitations, and suggests potentially important future directions. Following a brief historical overview, the review summarises knowledge about demographic and epidemiological characteristics, distal and proximal risk factors, current treatment directions, and prevention. There is still a great deal to learn about the causes and treatments of child and adolescent anxiety disorders. By amalgamating our current knowledge, this review provides a window to the research directions that are likely to lead to future advances.

The association between mnemonic discrimination ability and differential fear learning

BACKGROUND AND OBJECTIVES

It is important to be able to learn which stimuli in our surroundings predict aversive outcomes. To maintain emotional well-being, it is similarly important to be able to learn which stimuli predict safety. The ability to discriminate between stimuli that predict danger and safety has been suggested to not only have an emotional component, but also a cognitive one. One such candidate mechanism is mnemonic discrimination (MD), the ability to differentiate between two memories that are similar but not identical. In the present study, we wanted to examine if MD performance helps to explain inter-individual differences in the ability to acquire a differentiated fear response during fear conditioning.

METHODS

Participants performed a task assessing MD ability, and then underwent a fear conditioning procedure. Fear responses were measured using skin conductance responses (SCRs).

RESULTS

Results revealed no support for MD ability being associated with to which degree a differentiated fear response was acquired, or with the time needed to acquire such a response.

LIMITATIONS

Our only outcome measurement was SCRs. Future studies need to include fear ratings, expectancy ratings and neural responses. Future studies also need to examine this using a stimulus material where the conditioned stimulus and the safety stimulus are more difficult to distinguish from each other.

CONCLUSIONS

If MD ability has a role in inhibiting overgeneralization of fear learning, this does not seem to be driven by MD already during the initial learning.

Unique Associations between Conditioned Cognitive and Physiological Threat Responses and Facets of Anxiety Symptomatology in Youth

This study examined associations between anxiety symptomatology and cognitive and physiological threat responses during threat learning in a large sample of children and adolescents. Anxiety symptomatology severity along different dimensions (generalized anxiety, separation anxiety, social anxiety, and panic symptoms) was measured using parental and self-reports. Participants completed differential threat acquisition and extinction using an age-appropriate threat conditioning task. They then returned to the lab after 7-10 days to complete an extinction recall task that also assessed threat generalization. Results indicated that more severe overall anxiety was associated with greater cognitive and physiological threat responses during acquisition, extinction, and extinction recall. During acquisition and extinction, all anxiety dimensions manifested greater cognitive threat responses, while panic, separation anxiety, and social anxiety symptoms, but not generalized anxiety, were related to heightened physiological threat responses. In contrast, when we assessed generalization of cognitive threat responses, we found only generalized anxiety symptoms were associated with greater threat response generalization. The study provides preliminary evidence of specificity in threat responses during threat learning across youth with different anxiety symptoms.

Fear learning, avoidance, and generalization are more context-dependent for adults than adolescents

This study examined developmental differences in contextual and perceptual generalization of fear and avoidance learning. Adults (N = 39) and adolescents (N = 44) completed differential fear acquisition wherein each conditional stimulus (CS) appeared in a background context. In the dangerous context, one stimulus (CS+) predicted an aversive sound, and the other stimulus (CS-) did not. In the safe context, the aversive sound was never administered with either CS. During fear generalization, participants were presented with three generalization stimuli (GSs), ranging on a perceptual continuum from threat to safety stimuli, in both contexts. Participants then completed avoidance conditioning and avoidance generalization phases, allowing them to actively avoid the upcoming aversive sound by pressing an avoidance button. Developmental differences emerged in threat perception, physiological arousal, avoidance behavior, and eye movements during contextual fear learning and generalization. Adolescents showed less discrimination between stimuli and contexts than adults, resulting primarily from their elevated fear responses to safety and generalized stimuli. Developmental differences in fear learning should be further explored in future research, as they could explain why adolescence is a sensitive developmental period for anxiety.

Social relevance modulates multivariate neural representations of threat generalization in children and adults

Few studies have examined threat generalization across development and no developmental studies have compared the generalization of social versus nonsocial threat, making it difficult to identify contextual factors that contribute to threat learning across development. The present study assessed youth and adults' multivoxel neural representations of social versus nonsocial threat stimuli. Twenty adults (M_age  = 25.7 ± 4.9) and 16 youth (M_age  = 14.1 ± 1.7) completed two conditioning and extinction recall paradigms: one social and one nonsocial paradigm. Three weeks after conditioning, participants underwent a functional magnetic resonance imaging extinction recall task that presented the extinguished threat cue (CS+), a safety cue (CS-), and generalization stimuli (GS) consisting of CS-/CS+ blends. Across age groups, neural activity patterns and self-reported fear and memory ratings followed a linear generalization gradient for social threat stimuli and a quadratic generalization gradient for nonsocial threat stimuli, indicating enhanced threat/safety discrimination for social relative to nonsocial threat stimuli. The amygdala and ventromedial prefrontal cortex displayed the greatest neural pattern differentiation between the CS+ and GS/CS-, reinforcing their role in threat learning and extinction recall. Contrary to predictions, age did not influence threat representations. These findings highlight the importance of the social relevance of threat on generalization across development.

Return of fear following extinction in youth: An event-related potential study

The ability to learn to differentiate safety from danger matures gradually, particularly when such learning occurs over an extended time period. And yet, most research on fear learning examines the early phases of such learning and mainly in adults. The current study examined fear conditioning and extinction, as well as one form of extended learning, return of fear (ROF). Thirty-three typically developing children (age range: 7-14 years) completed fear conditioning and extinction; self-reports and psychophysiological indices were measured at this point. Two weeks later, children completed a ROF test (n = 23), and event-related potentials (ERPs) were recorded. Results indicated successful fear acquisition and extinction. Moreover, participants reported greater fear of the conditioned stimulus (CS+) than the safety stimulus (CS-) in the ROF test 2 weeks later. In electrophysiology data, ROF manifested as a larger late positive potential (LPP) response to the CS+ than the CS-. Finally, these differences in LPP responses were positively correlated with poorer extinction, as indicated by the GSR responses 2 weeks earlier. This is the first ERP study to demonstrate ROF in children. The LPP measure may index an interplay between inhibitory and excitatory brain-related processes underlying the long-term effects of fear learning.

Neural substrates of human fear generalization: A 7T-fMRI investigation

Fear generalization - the tendency to interpret ambiguous stimuli as threatening due to perceptual similarity to a learned threat - is an adaptive process. Overgeneralization, however, is maladaptive and has been implicated in a number of anxiety disorders. Neuroimaging research has indicated several regions sensitive to effects of generalization, including regions involved in fear excitation (e.g., amygdala, insula) and inhibition (e.g., ventromedial prefrontal cortex). Research has suggested several other small brain regions may play an important role in this process (e.g., hippocampal subfields, bed nucleus of the stria terminalis [BNST], habenula), but, to date, these regions have not been examined during fear generalization due to limited spatial resolution of standard human neuroimaging. To this end, we utilized the high spatial resolution of 7T fMRI to characterize the neural circuits involved in threat discrimination and generalization. Additionally, we examined potential modulating effects of trait anxiety and intolerance of uncertainty on neural activation during threat generalization. In a sample of 31 healthy undergraduate students, significant positive generalization effects (i.e., greater activation for stimuli with increasing perceptual similarity to a learned threat cue) were observed in the visual cortex, thalamus, habenula and BNST, while negative generalization effects were observed in the dentate gyrus, CA1, and CA3. Associations with individual differences were underpowered, though preliminary findings suggested greater generalization in the insula and primary somatosensory cortex may be correlated with self-reported anxiety. Overall, findings largely support previous neuroimaging work on fear generalization and provide additional insight into the contributions of several previously unexplored brain regions.

Reducing Generalization of Conditioned Fear: Beneficial Impact of Fear Relevance and Feedback in Discrimination Training

Anxiety patients over-generalize fear, possibly because of an incapacity to discriminate threat and safety signals. Discrimination trainings are promising approaches for reducing such fear over-generalization. Here we investigated the efficacy of a fear-relevant vs. a fear-irrelevant discrimination training on fear generalization and whether the effects are increased with feedback during training. Eighty participants underwent two fear acquisition blocks, during which one face (conditioned stimulus, CS+), but not another face (CS-), was associated with a female scream (unconditioned stimulus, US). During two generalization blocks, both CSs plus four morphs (generalization stimuli, GS1-GS4) were presented. Between these generalization blocks, half of the participants underwent a fear-relevant discrimination training (discrimination between CS+ and the other faces) with or without feedback and the other half a fear-irrelevant discrimination training (discrimination between the width of lines) with or without feedback. US expectancy, arousal, valence ratings, and skin conductance responses (SCR) indicated successful fear acquisition. Importantly, fear-relevant vs. fear-irrelevant discrimination trainings and feedback vs. no feedback reduced generalization as reflected in US expectancy ratings independently from one another. No effects of training condition were found for arousal and valence ratings or SCR. In summary, this is a first indication that fear-relevant discrimination training and feedback can improve the discrimination between threat and safety signals in healthy individuals, at least for learning-related evaluations, but not evaluations of valence or (physiological) arousal.

Influence of Perceptual and Conceptual Information on Fear Generalization: A Behavioral and Event-Related Potential Study

Learned fear can be generalized through both perceptual and conceptual information. This study investigated how perceptual and conceptual similarities influence this generalization process. Twenty-three healthy volunteers completed a fear-generalization test as brain activity was recorded in the form of event-related potentials (ERPs). Participants were exposed to a de novo fear acquisition paradigm with four categories of conditioned stimuli (CS): two conceptual cues (animals and furniture); and two perceptual cues (blue and purple shapes). Animals (C+) and purple shapes (P+) were paired with the unconditioned stimulus (US), whereas furniture (C-) and blue shapes (P-) never were. The generalized stimuli were thus blue animals (C+P+, determined danger), blue furniture (C-P+, perceptual danger), purple animals (C+P-, conceptual danger), and purple furniture (C-P-, determined safe). We found that perceptual cues elicited larger fear responses and shorter reaction times than did conceptual cues during fear acquisition. This suggests that a perceptually related pathway might evoke greater fear than a conceptually based route. During generalization, participants were more afraid of C+ exemplars than of C- exemplars. Furthermore, C+ trials elicited greater N400 amplitudes. Thus, participants appear able to use conceptually based cues to infer the value of the current stimuli. Additionally, compared with C+ exemplars, we found an enhanced late positive potential effect in response to C- exemplars, which seems to reflect a late inhibitory process and might index safety learning. These findings may offer new insights into the pathological mechanism of anxiety disorders.

Emerging Domain-Based Treatments for Pediatric Anxiety Disorders

Domain-specific cognitive training treatments for pediatric anxiety disorders rely on accurate and reliable identification of specific underlying deficits and biases in neurocognitive functions. Once identified, such biases can serve as specific targets for therapeutic intervention. Clinical translations typically reflect mechanized training protocols designed to rectify the identified biases. Here, we review and synthesize research on key neurocognitive processes that emerge as potential targets for specialized cognitive training interventions in pediatric anxiety disorders in the domains of attention, interpretation, error monitoring, working memory, and fear learning. For each domain, we describe the current status of target establishment (i.e., an association between pediatric anxiety and a specific neurocognitive process), and then review extant translational efforts regarding these targets and the evidence supporting their clinical utility in youths. We then localize each of the domains within the path leading to efficacious, evidence-supported treatments for pediatric anxiety, providing a roadmap for future research. The review indicates that specific cognitive targets in pediatric anxiety have been established in all the reviewed domains except for fear learning, where a clear target is yet to be elucidated. In contrast, evidence for clinical efficacy emerged only in the threat-related attention domain, with some preliminary findings in the domains of interpretation and working memory. The path to clinical translation in the domain of error monitoring is yet unclear. Implications and potential avenues for future research and translation are discussed.

Brief Training to Modify the Breadth of Attention Influences the Generalisation of Fear

Background

Generalisation of fear from dangerous to safe stimuli is an important process associated with anxiety disorders. However, factors that contribute towards fear (over)-generalisation remain poorly understood. The present investigation explored how attentional breadth (global/holistic and local/analytic) influences fear generalisation and, whether people trained to attend in a global vs. local manner show more or less generalisation.

Methods

Participants (N = 39) were shown stimuli which comprised of large ‘global’ letters and smaller ‘local’ letters (e.g. an F comprised of As) and they either had to identify the global or local letter. Participants were then conditioned to fear a face by pairing it with an aversive scream (75% reinforcement schedule). Perceptually similar, but safe, faces, were then shown. Self-reported fear levels and skin conductance responses were measured.

Results

Compared to participants in Global group, participants in Local group demonstrated greater fear for dangerous stimulus (CS +) as well as perceptually similar safe stimuli.

Conclusions

Participants trained to attend to stimuli in a local/analytical manner showed higher magnitude of fear acquisition and generalisation than participants trained to attend in a global/holistic way. Breadth of attentional focus can influence overall fear levels and fear generalisation and this can be manipulated via attentional training.

Reducing avoidance in adults with high spider fear using perceptual discrimination training

BACKGROUND

Fear overgeneralization is a central feature of anxiety disorders and can lead to excessive avoidance. As perceptual discrimination is a key component of fear overgeneralization, a perceptual discrimination training task was created aimed at improving perceptual discrimination and reducing fear overgeneralization.

METHODS

Participants with high spider fear were randomized into training or placebo conditions. After completing their assigned task, perceptual discrimination was tested. Thereafter, participants completed a behavioral avoidance test, consisting of five stimuli ranging from a paper spider to a live tarantula. Last, participants completed a threat/safety discrimination task using schematic morphs ranging from a flower to a spider, while self-report and skin conductance responses were collected.

RESULTS

The training group showed better perceptual discrimination during the test than did the placebo group. Furthermore, as stimuli became increasingly similar to a live spider, participants in the training group exhibited decreased avoidance behavior. Finally, participants in the training group indicated that schematic morphs were less similar to a spider and showed less physiological arousal than did the placebo group.

CONCLUSIONS

Together, these results attest to the possible clinical relevance of the perceptual discrimination training.