Increases and decreases in fear potentiated startle during fear acquisition: A latent class growth analysis.

Abstract

Objective: Findings from recent Latent Class Growth Analysis (LCGA) studies suggest that conditioned fear responding may be more heterogeneous than initially thought. However, it is unclear whether distinct subgroups may exist which differ with respect to the direction of change in conditioned fear responding. The primary purpose of this study was to examine heterogeneity in the direction of change in conditioned fear responding during fear acquisition. Method: This study applied LCGA to data derived from a differential fear conditioning experiment to detect latent subgroups in an undergraduate sample (n = 65). Conditioned fear responding was operationalized using fear-potentiated startle (FPS); startles were measured using electromyography (EMG). Results: Fit indices demonstrated that a two-class linear model best fit the data. LCGA-derived classes included a majority Decreasing Fear group (83.1% of the sample) which displayed decreasing FPS during acquisition (EST slope = −0.066; p = .001) and a minority Increasing Fear group (16.9% of the sample) which displayed increasing FPS during acquisition (EST slope = 0.12; p = .006). Conclusions: The detection of latent subgroups with directionally opposite changes in conditioned fear responding is a novel finding and suggests the presence of distinct subpopulations. When faced with a repeated mild stressor, a minority of individuals may be more susceptible to elevations in conditioned fear. Due to the biologically and psychologically taxing nature of elevated conditioned fear, this finding may have implications for public health and psychopathology. Future studies with larger samples are needed to replicate and extend this finding. Public Significance StatementThis study suggests the existence of distinct subgroups of humans defined by differences in conditioned fear responding after repeated exposure to a predictable mild stressor. When repeatedly exposed to a visual cue that signals impending stressor exposure, individuals belonging to the more common subgroup may respond with decreasing conditioned fear responding while individuals belonging to the less prevalent subgroup may respond with increasing conditioned fear responding.

Multiverse analyses of fear acquisition and extinction retention in posttraumatic stress disorder

“…Finally, although our study focuses on the conventional DSM‐based diagnosis of PTSD, PTSD is clinically and biologically heterogeneous (Galatzer‐Levy et al, 2017; Lewis et al, 2020; Liberzon, 2018). Thus, fear extinction retention deficits may exist in only a yet to be confirmed subset of PTSD patients (Liberzon, 2018; Lonsdorf & Merz, 2017), and we recommend that future studies apply multiverse analysis to the exploration of fear extinction retention in theory‐based (e.g., hypo versus hyper reactive (Lang et al, 2016)) or statistically‐derived (Galatzer‐Levy et al, 2017; Lewis et al, 2021) PTSD subgroups.…”