Impact of threat relevance on P3 event-related potentials in combat-related post-traumatic stress disorder

The purpose of this study was to examine electrophysiological response to t rauma-relevant stimuli in combat-related post-traumatic stress disorder (PT SD). Study design incorporated comparison of 10 Vietnam War veterans with P TSD diagnosis to 10 Vietnam War veterans with no mental disorder diagnosis on P3 components in a series of two oddball tasks (trauma-relevant threat, trauma-irrelevant throat) counterbalanced fur order. Each task included hig h probahility emotionally neutral distracter words and low probability neut ral target words, but differed in the content of low probability threat wor ds. Whereas threat words in the trauma-relevant oddball task pertained dire ctly to combat trauma, threat words in the trauma-irrelevant oddball task w ere socially threatening words. Results revealed that, in comparison to hea lthy combat veterans, those diagnosed with PTSD demonstrated: (a) attenuate d P3 response to neutral target items at selected electrode sites across bo th oddball tasks; and (b) increased responsivity to trauma-relevant combat stimuli but not to trauma-irrelevant social-threat stimuli at frontal elect rode sites (F3, F4). Results are consistent with resource allocation models of PTSD, which suggest that PTSD is characterized by attentional bias to t hreat stimuli at the expense of attention to emotionally neutral informatio n. (C) 2001 Elsevier Science Ireland Ltd. All lights reserved.