Biomarkers of Threat Reactivity in Posttraumatic Stress Disorder

Proposal details

Title: Biomarkers of Threat Reactivity in Posttraumatic Stress Disorder
Research Area(s): PTSD and other Anxiety Disorders
Background: There are a range of proposed indicators which distinguish PTSD from controls but these have not been examined in the same subjects, such that the relative importance of each marker, or the combined impact of markers, is unknown. Previous studies have reported heightened heart rate, skin conductance response and amygdala/insula activity to trauma-relevant stimuli (Rauch et al., 2006). Some neuroimaging studies have also found increased limbic activity to fearful faces in PTSD (Williams et al., 2006; Felmingham et al., 2007). These findings accord with prevailing neurobiological models of PTSD. However, previous studies have been limited by small sample sizes, they have typically not examined autonomic and central responses to innate threat stimuli, and they have not employed integrative analyses to identify concurrent autonomic and central biomarkers of threat reactivity in PTSD. We propose the following candidate markers for threat reactivity in PTSD, relevant to our proposed mechanism of disturbance in brain-body arousal systems that regulate responses to significant stimuli (including threat, Gordon et al., 2007): General Cognition: (Vigilance) Social Cognition: (Emotion Quotient; NEO-PI) Body Arousal (Startle HR/EMG/SCR and HR variability) Brain Arousal (EEG Beta) Brain function related to significance: (P3a novelty in oddball, Face ERP).
Aims: Theoretical models propose that individuals with PTSD have heightened autonomic and limbic reactivity to threat. This project aims to identify the specific convergent markers of this reactivity. We hypothesize that individuals with PTSD will display heightened sympathetic reactivity, startle responses, and larger and earlier event-related potentials to threat stimuli.
Method: Comparison of PTSD and controls on vigilance and social cognition measures, heart rate variability, SCL, startle EMG/HR and SCR (startle modulation paradigm), P3a novelty (oddball), and event-related potentials to emotional faces (including angry and fearful faces).