Event-related potential studies of post-traumatic stress disorder: a critical review and synthesis

Abstract

Despite the sparseness of the currently available data, there is accumulating evidence of information processing impairment in post-traumatic stress disorder (PTSD). Studies of event-related potentials (ERPs) are the main tool in real time examination of information processing. In this paper, we sought to critically review the ERP evidence of information processing abnormalities in patients with PTSD. We also examined the evidence supporting the existence of a relationship between ERP abnormalities and symptom profiles or severity in PTSD patients. An extensive Medline search was performed. Keywords included PTSD or post-traumatic stress disorder, electrophysiology or EEG, electrophysiology, P50, P100, N100, P2, P200, P3, P300, sensory gating, CNV (contingent negative variation) and MMN (mismatch negativity). We limited the review to ERP adult human studies with control groups which were reported in the English language. After applying our inclusion-exclusion review criteria, 36 studies were included. Subjects exposed to wide ranges of military and civilian traumas were studied in these reports. Presented stimuli were both auditory and visual. The most widely studied components included P300, P50 gating, N100 and P200. Most of the studies reported increased P300 response to trauma-related stimuli in PTSD patients. A smaller group of studies reported dampening of responses or no change in responses to trauma-related and/or unrelated stimuli. P50 studies were strongly suggestive of impaired gating in patients with PTSD. In conclusion, the majority of reports support evidence of information processing abnormalities in patients with PTSD diagnosis. The predominance of evidence suggests presence of mid-latency and late ERP components differences in PTSD patients in comparison to healthy controls. Heterogeneity of assessment methods used contributes to difficulties in reaching firm conclusions regarding the nature of these differences. We suggest that future ERP-PTSD studies utilize standardized assessment scales that provide detailed information regarding the symptom clusters and the degree of symptom severity. This would allow assessment of electrophysiological indices-clinical symptoms relationships. Based on the available data, we suggest that ERP abnormalities in PTSD are possibly affected by the level of illness severity. If supported by future research, ERP studies may be used for both initial assessment and treatment follow-up.

Altered processing of visual emotional stimuli in posttraumatic stress disorder: an event-related potential study

“…It is tempting to hypothesize that such overgeneralization may underlie attentional deficits often reported in PTSD patients, as even "insignificant" stimuli ( i.e., neutral stimuli) affect cortical response, thus also affecting the processing of subsequent stimuli. This view is consistent with the P500, suggested to be involved in updating working memory representations (Javanbakht et al, 2011), reported to be impaired in patients with PTSD .…”

From Pavlov to PTSD: The extinction of conditioned fear in rodents, humans, and anxiety disorders

“…Heart rates can be measured through various means including pulse oximetry. Electroencephalography (EEG) event-related potential (ERP) studies of conditioning and extinction in healthy humans and PTSD have been reviewed elsewhere (Javanbakht, Liberzon, Amirsadri, Gjini, & Boutros, 2011; Pitman et al, 2012), and will not be discussed here.…”

Decreased somatosensory activity to non-threatening touch in combat veterans with posttraumatic stress disorder

“…Most of these studies have recorded event-related potentials (ERP) using trauma-eliciting stimuli and shown significant increases in the P300 response (for a review see Javanbakht et al, 2011), although Bae et al (2011) found reduced P300 current-source density in patients with PTSD compared to healthy controls in response to non-threatening auditory stimuli.. These seemingly disparate results are consistent with a meta-analysis of ERP studies in PTSD, which found enhanced responses for trauma-related stimuli and reduced responses for neutral stimuli, particularly in the parietal cortex (Karl et al, 2006a).…”