A CNV-distraction paradigm in combat veterans with posttraumatic stress disorder

Contingent negative variation as an evaluation indicator of neurocognitive disorder after traumatic brain injury

Introduction

Neurocognitive disorders are commonly observed in patients suffering from traumatic brain injury (TBI). Methods to assess neurocognitive disorders have thus drawn the general attention of the public, especially electrophysiology parameter such as contingent negative variation (CNV), which has been given more emphasis as a neurophysiological marker in event-related potentials (ERPs) for diagnosing a neurocognitive disorder and assessing its severity. The present study focused on the correlations between CNV parameters and levels of daily living activities and social function to explore the potential of CNV as an objective assessment tool.

Methods

Thirty-one patients with a diagnosis of neurocognitive disorder after a TBI according to ICD-10 were enrolled as the patient group, and 24 matched healthy volunteers were enrolled as the control group. The activity of daily living scale, functional activities questionnaire, social disability screening schedule, and scale of personality change following TBI were used to assess daily living activity and social function.

Results

The scale scores in patients were significantly higher than those in controls. Maximum amplitudes before S2 and during the post-imperative negative variation (PINV) period were also significantly higher in the patient group compared to the control group and were positively correlated with four scale scores. The duration of PINV at Fz and Cz was significantly shorter in the patient group than in the control group. The CNV return to baseline from a positive wave at electrode Fz and Cz occurred significantly earlier in the control group than in the patient group, while at Pz, the result showed the opposite.

Conclusion

Lower amplitudes of CNV were associated with more severe neurocognitive disorder and greater impairments in daily life abilities and social function. The duration of PINV and the latency of returning to baseline from a positive wave were correlated with the neurocognitive disorder to some extent. CNV could be used as an objective, electrophysiology-based parameter for evaluating the severity of the neurocognitive disorder and personality changes after TBI.

Attention deficits as a key player in the symptomatology of posttraumatic stress disorder: A review

Posttraumatic stress disorder (PTSD) is a debilitating psychiatric disorder characterized by symptoms such as re-experiencing of the psychotrauma and hyperarousal. Although current literature mainly discusses the emotionally related aspects of these symptoms, studies also highlight the relation between re-experiencing, hyperarousability, and attention deficits, which are associated with poorer daily function and reduced quality of life. This review provides a comprehensive analysis of the existing research on attention deficits among adults with PTSD. A systematic search through five databases resulted in the inclusion of 48 peer-reviewed, English-language articles, describing 49 distinct studies. Using a total of 47 different attentional assessment tools, the majority of studies investigated sustained (n = 40), divided (n = 16), or selective (n = 14) attention. A total of 30 studies (61.2%) found significant correlations between PTSD symptoms and attention deficits, and 10 studies (20.4%) found that higher levels of attention deficits were predictive of worse PTSD symptoms. Moreover, neuroimaging results of six (f)MRI and three EEG studies identified various potential neurobiological pathways involved, including (pre)frontal attention networks. Together, the body of research shows that attention deficits in individuals with PTSD are common and occur in surroundings with emotionally neutral stimuli. Nonetheless, current treatment strategies do not target these attentional difficulties. We propose a novel perspective to PTSD diagnosis and treatment strategies based on attention deficits and their relation with top-down regulation of re-experiencing and subsequent other PTSD symptoms.

Chronic stress and anticipatory event-related potentials: the moderating role of resilience

Chronic stress exposure is associated with impaired cognitive function; however, the underlying mechanism is not yet clear. This study investigated the association between perceived chronic stress and anticipatory processing, measured by event-related potentials, and the moderating role of resilience on this relationship in healthy adults. Fifty-nine healthy volunteers (22.52 ± 1.75 years) underwent a continuous performance test, and anticipatory processing was indexed with the contingent negative variation (CNV) of event-related potentials, the Cohen Perceived Stress Scale, and the Connor-Davidson Resilience Scale. The results showed that greater reports of perceived chronic stress were associated with more negative early CNVs; however, there was no significant relationship between perceived chronic stress and behavioral performance on the continuous performance test. More importantly, the relationship between perceived chronic stress and early CNV was moderated by resilience as the association between the Cohen Perceived Stress Scale score and early CNV amplitude was significant for low and average levels of resilience. These results not only suggest that chronic stress may lead to decreased cognitive efficiency in cortical anticipatory activity, but also underscore the role of resilience as a key protective factor in decreased cognitive efficiency.

Contingent negative variation in acute trauma patients: A prospective exploratory study

It is still unclear why some individuals completely recover after an acute trauma and others develop a long-lasting post-traumatic stress disorder (PTSD). This study investigates whether the contingent negative variation (CNV) - a slow negative event-related potential - may be associated with the occurrence of PTSD after acute trauma. CNV (auditory 2-stimulus reaction time paradigm) was recorded within one month as well as 6 months after an acute trauma (dangerous or grave physical injuries, witnessing of attempted suicide or murder, robbery, extortion, accidents, heavy illness, death or loss of an important person, hostage-taking) in 39 otherwise healthy adults and compared with CNV recordings in 38 healthy control subjects without potentially traumatizing experience in their history. According to their subsequent clinical course, these subjects were divided into two groups: participants who recovered completely 1 month after the trauma (PTSD- group, n = 31), and those who began to experience PTSD (PTSD+ group, n = 8). Patients from both trauma groups were characterized by a significantly longer reaction time immediately after the trauma. The PTSD+ group demonstrated lower amplitudes of the late CNV component immediately and six months after the trauma compared with the PTSD- and the control group. Whether the lower CNV amplitudes in patients who develop PTSD after the acute trauma, which is already present in the first days after the trauma, may be related to a higher risk for development of PTSD in these subjects, this has to be clarified in further prospective studies.

Personality and Augmenting/Reducing (A/R) in auditory event-related potentials (ERPs) during emotional visual stimulation

An auditory augmenting/reducing ERP paradigm recorded for 5 intensity tones with emotional visual stimulation was used, for the first time, to test predictions derived from the revised Reinforcement Sensitivity Theory (rRST) of personality with respect to two major factors: behavioral inhibition system (BIS), fight/flight/freeze system (FFFS). Higher BIS and FFFS scores were negatively correlated with N1/P2 slopes at central sites (C3, Cz, C4). Conditional process analysis revealed that the BIS was a mediator of the association between the N1/P2 slope and the FFFS scores. An analysis of covariance showed that lower BIS scorers exhibited larger N1/P2 amplitudes across all tone intensities while watching negative, positive and neutral pictures. Additionally, lower FFFS scorers compared to higher FFFS scorers disclosed larger N1/P2 amplitudes to the highest tone intensities and these differences were even more pronounced while watching positive emotional pictures. Findings were explained assuming the operation of two different, but related processes: transmarginal inhibition for the BIS; the attention/emotional gating mechanism regulating cortical sensory input for the FFFS trait. These findings appear consistent with predictions derived from the rRST, which traced fear and anxiety to separate but interacting neurobehavioural systems.

Identifying Electrophysiological Prodromes of Post-traumatic Stress Disorder: Results from a Pilot Study

The objective of this research project is the identification of a physiological prodrome of post-traumatic stress disorder (PTSD) that has a reliability that could justify preemptive treatment in the sub-syndromal state. Because abnormalities in event-related potentials (ERPs) have been observed in fully expressed PTSD, the possible utility of abnormal ERPs in predicting delayed-onset PTSD was investigated. ERPs were recorded from military service members recently returned from Iraq or Afghanistan who did not meet PTSD diagnostic criteria at the time of ERP acquisition. Participants (n = 65) were followed for up to 1 year, and 7.7% of the cohorts (n = 5) were PTSD-positive at follow-up. The initial analysis of the receiver operating characteristic (ROC) curve constructed using ERP metrics was encouraging. The average amplitude to target stimuli gave an area under the ROC curve of greater than 0.8. Classification based on the Youden index, which is determined from the ROC, gave positive results. Using average target amplitude at electrode Cz yielded Sensitivity = 0.80 and Specificity = 0.87. A more systematic statistical analysis of the ERP data indicated that the ROC results may simply represent a fortuitous consequence of small sample size. Predicted error rates based on the distribution of target ERP amplitudes approached those of random classification. A leave-one-out cross validation using a Gaussian likelihood classifier with Bayesian priors gave lower values of sensitivity and specificity. In contrast with the ROC results, the leave-one-out classification at Cz gave Sensitivity = 0.65 and Specificity = 0.60. A bootstrap calculation, again using the Gaussian likelihood classifier at Cz, gave Sensitivity = 0.59 and Specificity = 0.68. Two provisional conclusions can be offered. First, the results can only be considered preliminary due to the small sample size, and a much larger study will be required to assess definitively the utility of ERP prodromes of PTSD. Second, it may be necessary to combine ERPs with other biomarkers in a multivariate metric to produce a prodrome that can justify preemptive treatment.

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

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.

Eye tracking and visual attention to threating stimuli in veterans of the Iraq war

Theoretical and clinical characterizations of attention in PTSD acknowledge the possibility for both hypervigilance and avoidance of trauma-relevant stimuli. This study used eye tracking technology to investigate visual orientation and attention to traumatic and neutral stimuli in nineteen veterans of the Iraq war. Veterans saw slides in which half the screen had a negatively valenced image and half had a neutral image. Negatively valenced stimuli were further divided into stimuli that varied in trauma relevance (either Iraq war or civilian motor vehicle accidents). Veterans reporting relatively higher levels of PSTD symptoms had larger pupils to all negatively valenced pictures and spent more time looking at them than did veterans lower in PTSD symptoms. Veterans higher in PTSD symptoms also showed a trend towards looking first at Iraq images. The findings suggest that post-traumatic pathology is associated with vigilance rather than avoidance when visually processing negatively valenced and trauma-relevant stimuli.