Event-related potential dysfunction in posttraumatic stress disorder: the role of numbing

The purpose of this study was to examine the relationship between disturbance in event-related potentials (ERPs) and symptom clusters in posttraumatic stress disorder (PTSD). ERPs were recorded in 17 unmedicated civilian PTSD patients and 17 age- and sex-matched controls during a conventional auditory oddball task. PTSD symptom clusters (re-experiencing, active avoidance, numbing, hyperarousal) were correlated with ERP measures. The PTSD group showed ERP disturbances to target stimuli (reduced P200 and P300 and increased N200 amplitude, increased N200 and P300 latency) and reduced P200 amplitude to common stimuli compared to the control group. A significant negative correlation was found between the intensity of numbing symptoms and parietal P300 amplitude. This study replicates findings of disturbed N200 and P300 components in PTSD, reflecting impairments in stimulus discrimination and attention. The finding that numbing was associated with reduced attention processing (P300) is consistent with models positing a relationship between disordered arousal and attention in PTSD.