Response Primacy in Fear Conditioning: Disentangling the Contributions Of UCS VS. UCR Intensity

Examining the indirect contributions of irritability and chronic interpersonal stress on symptoms of anxiety and depression in adolescents

BACKGROUND

Chronic interpersonal stress has been identified as predictive of anxiety and depression. However, more research is needed to understand predictors of chronic interpersonal stress and mediators of its relationship with anxiety and depression. Irritability, a transdiagnostic symptom closely related to chronic interpersonal stress, may provide more insight into this relationship. While some research has demonstrated that irritability is related to chronic interpersonal stress, directionality is unknown. A bidirectional relationship between irritability and chronic interpersonal stress was hypothesized, such that irritability mediates the relationship between chronic interpersonal stress and internalizing symptoms and chronic interpersonal stress mediates the relationship between irritability and internalizing symptoms.

METHODS

This study used three cross-lagged panel models to investigate the indirect effects of irritability and chronic interpersonal stress on anxiety and depression symptoms using data from 627 adolescents (68.9 % female, 57.7 % white) over a six-year period.

RESULTS

In partial support for our hypotheses, we found that the relationships between chronic interpersonal stress and both fears and anhedonia were mediated by irritability, and that the relationship between irritability and anhedonia was mediated by chronic interpersonal stress.

LIMITATIONS

Study limitations include some temporal overlap in symptom measurements, an irritability measure that has not been previously validated to measure the construct, and lack of a lifespan perspective.

CONCLUSIONS

More targeted approaches in intervention for both chronic interpersonal stress and irritability may improve prevention and intervention efforts to address anxiety and depression.

Sex differences in salivary cortisol in response to acute stressors among healthy participants, in recreational or pathological gamblers, and in those with posttraumatic stress disorder

Sex differences in incidence and severity of some stress-related, neuropsychiatric disorders are often reported to favor men, suggesting that women may be more vulnerable to aberrant hypothalamic-pituitary-adrenal (HPA) axis responses to stress. In this review, we discuss several investigations that we, and others, have conducted assessing salivary cortisol as a measure of HPA function. We have examined basal cortisol among healthy men and women and also following acute exposure to stressors. Among healthy participants, men had higher basal cortisol levels than did women. In response to acute stressors, such as carbon dioxide or noise, respectively, cortisol levels were comparable between men and women or higher among women. We have also examined cortisol levels among those with problem eating, gambling, or posttraumatic stress disorder (PTSD). Women with restrained eating habits have higher basal cortisol levels than do women without restrained eating habits. Pathological gamblers have more aberrant stress response to gambling stimuli than do recreational gamblers, and these effects are more prominent among men than women. Men who have motor vehicle accident related PTSD, demonstrate more aberrant cortisol function, than do their female counterparts. Although these sex differences in cortisol seem to vary with type of stress exposure and/or pathophysiological status of the individual, other hormones may influence cortisol response. To address this, cortisol levels among boys and girls with different stress-related experiences, will be the subject of future investigation.

Context and renewal of conditioned fear: an experimental evaluation using 20% carbon dioxide-enriched air as an unconditioned stimulus

This analogue experiment used fear conditioning and extinction procedures to establish and reduce fearful responding and then test for fear renewal following a context change. Healthy undergraduates (N=61) underwent a differential fear conditioning procedure using geometric shapes as conditioned stimuli (CS) and inhalations of 20% CO(2)-enriched air as an aversive unconditioned stimulus (US). Across phases (i.e., habituation, acquisition, extinction, and test), red and green ambient lighting served as contextual stimuli, and electrodermal and evaluative ratings were assessed as indices of conditioned fear. The control group underwent extinction and test phases under identical conditions (i.e., no context changes). The experimental groups either underwent acquisition and test phases in one context and the intervening extinction phase in a different context (A-B-A), or underwent acquisition and extinction phases in one context and the test phase in a novel context (A-A-B). Consistent with expectation, fear renewal was observed when the test context matched the acquisition context. This effect was modest for electrodermal responses, but reasonably robust for evaluative responses. The role of context in the subsequent renewal of fear following exposure-based treatment is discussed.

Evaluative differential conditioning of disgust: a sticky form of relational learning that is resistant to extinction

The present study sought to (a) test whether autonomic (i.e., electrodermal) and evaluative conditioning can be differentially established to verbal CSs, and (b) whether extinction procedures can reliably attenuate differential conditioned evaluative responding. Thirty undergraduates underwent a 10-min adaptation period followed by three consecutive conditioning phases: habituation, acquisition, and extinction. Conditioning involved participants viewing two semi-randomly presented words on a computer monitor. During acquisition, one word (CS+) was reliably paired 12 times with the UCS (pictorial stimuli depicting bodily mutilation), whereas the remaining word (CS-) was presented 12 times and reliably followed by neutral pictures (inanimate common objects). As predicted, electrodermal and evaluative responses during acquisition were of larger magnitude to the CS+ compared to the CS-. During extinction, participants continued to evaluate the CS+ as more disgusting relative to the CS-, whereas distress and fear-related emotional ratings attenuated across extinction trials. The implications of these findings for the modifiability of disgust-based evaluative responses in specific anxiety disorders will be discussed.

Interoceptive fear conditioning as a learning model of panic disorder: An experimental evaluation using 20% CO2-enriched air in a non-clinical sample

Despite the role afforded interoceptive fear conditioning in etiologic accounts of panic disorder, there are no good experimental demonstrations of such learning in humans. The aim of the present study was to evaluate the interoceptive conditioning account using 20% carbon dioxide (CO(2))-enriched air as an interoceptive conditioned stimulus (CS) (i.e., physiologically inert 5-s exposures) and unconditioned stimulus (US) (i.e., physiologically prepotent 15-s exposures). Healthy participants (N=42) were randomly assigned to one of three conditions: a CS-only, contingent CS-US pairings, or unpaired/non-contingent CS and US presentations. Electrodermal and self-report (e.g., distress, fear) served as indices of conditioned emotional responding. Results showed greater magnitude electrodermal and evaluative fear conditioning in the paired relative to the CS-only condition. The explicitly unpaired condition showed even greater electrodermal and evaluative responding during acquisition, and marked resistance to extinction. The latter results are consistent with the possibility that the unpaired procedure constituted a partial reinforcement procedure in which CO(2) onset was paired with more extended CO(2) exposure on 50% of the trials. Overall, the findings are consistent with contemporary learning theory accounts of panic.

Multimodal classical conditioning of fear: contributions of direct, observational, and verbal experiences to current fears

The authors propose that a multimodal classical conditioning model be considered when clinicians or clinical researchers study the etiology of fears and anxieties learned by human beings. They argue that fears can be built through the combined effects of direct, observed, and verbally presented classical conditioning trials. Multimodal classical conditioning is offered as an alternative to the three pathways to fear argument prominent in the human fear literature. In contrast to the three pathways position, the authors present theoretical arguments for why "learning by observation" and "learning through the receipt of verbal information" should be considered classical conditioning through observational and verbal modes. The paper includes a demonstration of how data, commonly collected in research on the three pathways to fear, would be studied differently using a multimodal classical conditioning perspective. Finally, the authors discuss implications for assessment, treatment, and prevention of learned fears in humans.