Aversive startle potentiation and fear pathology: Mediating role of threat sensitivity and moderating impact of depression

Abstract

Enhanced startle reactivity during exposure to unpleasant cues (aversive startle potentiation; ASP) appears in the RDoC matrix as a physiological index of acute threat response. Increased ASP has been linked to focal fear disorders and to scale measures of dispositional fearfulness (i.e., threat sensitivity; THT+). However, some studies have reported reduced ASP for fear pathology accompanied by major depressive disorder (MDD) or pervasive distress. The current study evaluated whether (a) THT+ as indexed by reported dispositional fearfulness mediates the relationship between fear disorders (when unaccompanied by depression) and ASP, and (b) depression moderates relations of THT+ and fear disorders with ASP. Fear disorder participants without MDD showed enhanced ASP whereas those with MDD (or other distress conditions) showed evidence of reduced ASP. Continuous THT+ scores also predicted ASP, and this association: (a) was likewise moderated by depression/distress, and (b) accounted for the relationship between ASP and fear pathology without MDD. These findings point to a role for the RDoC construct of acute threat, operationalized dispositionally, in enhanced ASP shown by individuals with fear pathology unaccompanied by distress pathology.

Keywords: Anxiety disorders; Depression; Fear; Startle; Threat sensitivity.

Figure 1

Bar graphs depicting average aversive startle potentiation as indexed by unpleasant-picture minus neutral-picture difference scores. Upper plot displays comparison between no-fear and fear disorder groups within non-depressed portion of study sample (i.e., no lifetime diagnosis of major depressive episode [MDD]). Lower plot displays same comparison for depressed (lifetime MDD present) portion of sample.

Figure 2

Scatter plots illustrating relationship between aversive-neutral startle potentiation scores and threat sensitivity THT+ as indexed by 55-item Trait Fear inventory (TF-55) scores for never-depressed (No MDD; upper) and depressed subsamples (MDD; lower) separately.