Posttraumatic stress disorder may be associated with impaired fear inhibition: Relation to symptom severity

• Authors: Tanja Jovanovic, Emory University; Seth Davin Norrholm, Emory University; Jennifer E. Fennell, Atlanta Veterans Affairs Medical Center; Megan Keyes, Atlanta Veterans Affairs Medical Center; Ana M. Fiallos, Emory University; Karyn M. Myers, Center for Behavioral Neuroscience; Michael E Davis, Emory University; Erica Duncan, Emory University
• Journal Title: Psychiatry Research
• Volume: Volume 167, Number 1-2
• Publisher: Elsevier: 12 months | 2009-05-15, Pages 151-160
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1016/j.psychres.2007.12.014
• Subjects: Psychology, Behavioral; Biology, Neuroscience; Health Sciences, Rehabilitation and Therapy
• Keywords: Acoustic Startle Response; Classical Conditioning; Fear-Potentiated Startle; Electromyography; PTSD; Human

Abstract

One of the central problems in posttraumatic stress disorder (PTSD) is the inability to suppress fear even under safe conditions. The neural underpinnings of fear is a clinically relevant issue that is poorly understood. This study assessed fear potentiation and fear inhibition using fear-potentiated startle in a conditional discrimination procedure (AX+/BX-). We hypothesized that patients with PTSD would show normal fear potentiation and impaired fear inhibition. 28 healthy volunteers and 27 PTSD patients (14 with low current symptoms, 13 with high current symptoms) were presented with one set of colored lights (AX trials) paired with aversive air blasts to the throat, and a different series of lights (BX trials) presented without air blasts. We then presented A and B together (AB trials) to see whether B would inhibit fear potentiation to A. All groups showed robust fear potentiation in that they had significantly greater startle magnitude on AX trials compared to noise alone trials. However, the high symptom PTSD group did not show fear inhibition: these subjects had significantly greater fear potentiation on the AB trials than both the controls and the low symptom PTSD patients.