Threat Acquisition and Extinction Differences between Patients with Panic Disorder or Specific Phobia and Non-Clinical Control Participants: A Systematic Review

The study of threat conditioning and extinction processes in anxiety disorders (AD) may further our understanding of the genesis, maintenance, and treatment of these conditions. As it stands, there have been multiple systematic reviews carried out in this area. Patient-control differences in threat acquisition and extinction have been investigated in relation to ADs, obsessive-compulsive disorder (OCD), and social anxiety disorder (SAD). However, this remains to be investigated in either panic disorder (PD) or specific phobia (SP). In this paper, a narrative systematic review was carried out to collate and critically assess the literature investigating patient-control differences in threat acquisition, extinction, and extinction retention processes in relation to PD and SP separately. Specifically, across fMRI, EEG, EMG, SCR, and self-report. This resulted in the inclusion of 14 PD studies and 7 SP studies. Across PD studies, the review identified reliable evidence for lowered discrimination between conditioned threat and safety cues, and mixed evidence for increased responding to the threat cue, during acquisition in PD patients vs. controls. Across SP studies, the review identified strong evidence for heightened discrimination between conditioned threat and safety cues during acquisition, and strong evidence for heightened responding to the threat cue during extinction, in SP patients vs. controls. In both PD and SP studies, patient-control differences were identified more readily in relation to subjective, as opposed to physiological, measures. The findings of this review are then critiqued and compared to the wider literature. Finally, implications, limitations, and directions for future research are discussed.