Category: Adult Anxiety
Background: Following an aversive experience in one context, fear often generalizes to similar contexts. This process, known as contextual fear generalization, multiplies perceived threats and plays a prominent role in fear maintenance (Lissek, 2012). Stress is thought to enhance maladaptive fear generalization, but mechanisms are unclear. Animal research suggests that stress hormones injected into the hippocampus impair ability to restrict fear responses to correct predictive cues (Kaouane et al, 2012) and human research similarly shows that oral administration of cortisol impairs contextualization of fear, leading to increased fear generalization (Van Ast et al, 2012). The current study aims to assess the relationship between stress and contextual fear generalization, and the extent to which trait anxiety and early life adversity moderate this relationship.
Methods: 51 adults were recruited at UCLA. On Day 1, participants completed self-report measures and were randomly assigned to a control or stress induction version of an arithmetic test. They then completed a differential context fear conditioning paradigm. Contexts (CTXs) were two versions of a nature scene, one depicted in wintertime and one in summertime. The unconditioned stimulus (US), an electric shock, occurred unpredictably during CTX+ presentation. Fear was measured via skin conductance response, startle eyeblink reflex, and subjective measures of US expectancy during each CTX. Participants returned one to three days after the first visit to complete a generalization test in which they viewed the CTX+, CTX- and four generalization contexts of parametrically varying degrees between them (i.e. nature scenes that gradually transition from one season to the next), all in absence of the US. Physiological indices and subjective report of US expectancy were again collected.
Results: Preliminary results revealed a significant main effect of CTX type on shock expectancy ratings during generalization test, F(5,43) = 15.457, p < .001, illustrating a gradient of US expectancy decreasing in linear fashion from CTX+ to CTX-, which validates the utility of this novel paradigm in assessing contextual fear generalization. Findings did not show a significant effect of stress on contextual fear generalization. Secondary analyses used mixed effects multilevel regression to compare low and high trait anxiety groups at each CTX on shock expectancy during generalization test. Greater trait anxiety was associated with higher expectancy of shock for the two context types most proximate in gradient to the CTX+ (i.e., CTX4 and CTX5). The significant omnibus test, X2(5) = 19.14, p = .0018, was driven by the high anxiety group demonstrating greater expectancy of shock to CTX4, z = 3.79, p < .0001, and CTX5, z = 3.2, p = .001, relative to the low anxiety group. Further results will be presented at time of conference.
Conclusion: Results are in line with research suggesting a strong link between anxiety and generalization, and build upon the literature by demonstrating that contextual fear generalization mirrors stimulus fear generalization patterns. Further analyses and clinical implications for anxiety, PTSD, and populations facing recurrent stress and adversity will be discussed.