Loss of automatic processes and blunted-affect in depression: a P3 study

Association of lifetime major depressive disorder with enhanced attentional sensitivity measured with P3 response in young adult twins

Major depression is associated with alterations in the auditory P3 event-related potential (ERP). However, the persistence of these abnormalities after recovery from depressive episodes, especially in young adults, is not well known. Furthermore, the potential influence of substance use on this association is poorly understood. Young adult twin pairs (N=177) from the longitudinal FinnTwin16 study were studied with a psychiatric interview, and P3a and P3b ERPs elicited by task-irrelevant novel sounds and targets, respectively. Dyadic linear mixed-effect models were used to distinguish the effects of lifetime major depressive disorder from familial factors and effects of alcohol problem drinking and tobacco smoking. P3a amplitude was significantly increased and P3b latency decreased, in individuals with a history of lifetime major depression, when controlling the fixed effects of alcohol abuse, tobacco, gender, twins' birth order, and zygosity. These results suggest that past lifetime major depressive disorder may be associated with enhanced attentional sensitivity.

Endogenous evoked potentials assessment in depression: a review

Over the past 15 years, researchers have shown an increasing interest in using event-related potentials (ERPs) to study depression. These studies generally fall into four classes: 1), ERPs as a means of detecting depression; 2), ERPs as a tool for distinguishing subtypes of depression; 3), ERPs as a measure of pharmacological effectiveness; 4), ERPs as indicators of defective cognitive operations in depressed subjects. Results from these heterogeneous approaches are often inconsistent and disappointing. Although some ERP components often show increased latencies and diminished amplitudes, these changes seem to reflect principally a variety of non-specific disorders affecting a wide range of cognitive functions rather than a precise and consistent deficit of a particular function. These disappointing results seem to be attributable to methodological problems (heterogeneous patient populations, disproportionate use of the odd-ball paradigm), and do not necessarily call into question the value of studying the ERPs. Furthermore, recent advances in ERP methodology have opened up new perspectives for ERP use in psychopathology.

Reduced brain responses to novel sounds in depression: P3 findings in a novelty oddball task

There have been conflicting findings as to whether the P3 brain potential to targets in oddball tasks is reduced in depressed patients. The P3 to novel distracter stimuli in a three-stimulus oddball task has a more frontocentral topography than P3 to targets and is associated with different cognitive operations and neural generators. The novelty P3 potential was predicted to be reduced in depressed patients. EEG was recorded from 30 scalp electrodes (nose reference) in 20 unmedicated depressed patients and 20 matched healthy controls during a novelty oddball task with three stimuli: infrequent target tones (12%), frequent standard tones (76%) and nontarget novel stimuli, e.g., animal or environment sounds (12%). Novel stimuli evoked a P3 potential with shorter peak latency and more frontocentral topography than the parietal-maximum P3b to target stimuli. The novelty P3 was markedly reduced in depressed patients compared to controls. Although there was a trend for patients to also have smaller parietal P3b to targets, this group difference was not statistically significant. Nor was there a group difference in the earlier N1 or N2 potentials. The novelty P3 reduction in depressed patients is indicative of a deficit in orienting of attention and evaluation of novel environmental sounds.

Are there common mechanisms in sensation seeking and reality distortion in schizophrenia? A study using memory event-related potentials

A growing literature suggests that the characteristics of sensation seeking and reality distortion expressed in schizophrenia share several mechanisms. In a previous study, the comparison of patients with high vs. low reality distortion using event-related potentials (ERPs) recorded in a recognition memory task for unfamiliar faces identified neural and cognitive anomalies specifically related to the expression of these symptoms. As a follow-up, this study investigated the ERP correlates of sensation seeking in schizophrenia using the same recognition memory protocol. ERPs have been recorded in controls (N=21) and schizophrenia patients separated into high (HSS; N=13) and low (LSS; N=17) scorers according to Zuckerman's Sensation Seeking Scale. The results show a reduced P2a that was found unrelated to reality distortion in the previous study of reality distortion. It identifies interference inhibition impairment as being specifically related to sensation seeking. On the other hand, HSS scorers display enhanced fronto-central and normal P600 effects also found in high reality distortion patients. These results indicate inappropriate context processing and mnemonic binding common to sensation seeking and reality distortion. LSS scorers also display a reduced temporal N300 similar to that found in low reality distortion patients. This anomaly could reflect the lower reactivity to emotionally significant stimuli that underlies anhedonia symptoms. Finally, the N400 effect and a late frontal effect are found in both HSS and LSS. Since they were unrelated to reality distortion, these indices have been related to basic aspects of schizophrenia, e.g., deficient knowledge integration, or other mechanisms, e.g. anxiety or impulsivity. In summary, the present study examines the strategy of investigating variables, such as temperamental characteristics, in addition to symptoms, to show how discrete impairments may contribute to the expression of the illness.

[The p300 cognitive event-related potential. II. Individual variability and clinical application in psychopathology]

The P300 wave is one of the cognitive components of the event-related potential (ERP) that is used to investigate the cognitive processes, and which can be used to study patient populations with a variety of psychiatric disorders. Its clinical utility has been increased by the identification of factors that contribute to the variability in its amplitude and latency. However, its value as a diagnostic index has not been entirely established. It can provide a useful recording of patients' information processing, and indicate the severity of the clinical state and its possible evolution. It can also assist in determining what therapeutic approach to adopt. In the present review, the findings in the literature concerning interindividual variation in the P300 wave are first described; several variables significantly influence the amplitude and latency of this wave, such as age, gender, intelligence and personality. Following this, the relevance of the data in the literature on the clinical applications of P300 in psychopathology is examined, including the studies undertaken to obtain an objective diagnostic index for mental disorders and also those carried out to assess the problems concerning the interpretation of information connected with the mental pathologies examined. P300-associated findings on dementia, schizophrenia, depression, alcoholism, drug addiction, anxiety disorders (panic disorder, obsessive-compulsive disorder, and post-traumatic stress syndrome) and on personality disorders (schizoid, antisocial or borderline personality disorder) have been examined in detail.

Frontal reactivity and sensation seeking an ERP study in skydivers

1. In the line of Zuckerman's studies on sensation seeking and optimal level of arousal, the authors hypothesized that high sensation seeking might be used to compensate for anhedonia due to basal arousal deficit. A population of interest was found with parachutists practicing skydiving, generally described as very high sensation seekers. 2. After clinical assessment of emotional and affective components, amplitudes of the frontal P3 of the ERP were used as indices of arousal. 3. Skydivers presented more negative symptoms (anhedonia and blunted-affect) than controls. This was observed in isolation from any depressive episode, which would suggest the presence of emotional deficit as a trait. As expected, skydivers presented more sensation seeking than controls. These two results taken together could indicate that sensation seeking is an adaptive reaction to anhedonia. 4. ERP results showed that frontal P3 amplitudes were larger in skydivers than in controls, whereas in a previous study we showed the opposite in depressed patients with a similar emotional deficit. This could indicate that the frontal P3 amplitude does not reflect the emotional deficit per se. We suggest that it rather reflects the capacity to use some behaviors which improve automatic attentional processes in order to obtain arousing stimulation that could counterbalance the emotional deficit. Depressions with emotional deficit might be due to the lack of such a capacity.

Correlations between standard auditory evoked potentials and symptomatology in a group of 50 schizophrenic patients

Standard auditory evoked potentials (AEP) were recorded in 50 schizophrenic patients and 47 normal controls. All patients were rated on the Brief Psychiatric Rating Scale (BPRS), the Scale for the Assessment of Negative Symptoms (SANS), the Scale for the Assessment of Positive Symptoms (SAPS), and the Positive and Negative Syndrome Scale (PANSS), and were classified in three groups (positive-type [n = 10], negative-type [n = 23]and mixed-type [n = 17]patients) according to the normative criteria suggested by Kay. The mean latencies of AEP components (N1, P2, N2) and mean peak-to-peak amplitudes (N1P2, P2N2) did not correlate with age, duration of illness, length of hospitalisation or neuroleptic dosage. The evoked response did not differ between the three groups of patients (positive, negative and mixed). There was only a trend (P = 0.075) to a longer N1 latency in the negative-type group and a shorter one in the positive-type group than in the mixed-type and the control groups. The latency of N1 component correlated significantly with negative symptoms of schizophrenia (SANS scores). This correlation was related to the severity of a depressive dimension of the disorder reflected by the "depressive factor" of BPRS or "affective flattening" and "avolition" subscales of SANS.

Cognitive and emotional deficits in early stages of HIV infection: an event-related potentials study

1. In order to inventory different Event-Related Potentials (ERP) modifications in HIV-infection the authors have evaluated 23 HIV-positive subjects and 12 HIV-negative subjects. ERP were recorded during an auditory oddball task. 2. Electrophysiological results showed that the latency of the N100 component of the ERP was significantly increased in HIV-positive subjects compared to the HIV-negative subjects. The latency of the N200 component of the ERP showed a similar tendency which just failed to reach significance when considering HIV-positive subjects vs HIV negative subjects. This result was in agreement with the literature which reported increased latencies in HIV infection. 3. Considering all subjects the authors have observed a correlation between the amplitude of the P300 and the emotional deficit. This correlation was stronger in subjects who presented an emotional deficit and was independent of any other psychopathological symptom. 4. The use of ERP appeared to be a sensitive technique to detect subclinical manifestations in HIV asymptomatic subjects and therefore would help to identify subjects at higher risk for developing cognitive impairments.

Heterogeneity of information-processing alterations according to dimensions of depression: an event-related potentials study

To identify alterations in elementary cognitive operations according to dimensions of depression, two stages of information processing, namely the response choice and the motor preparation stages, were explored using an event-related potential paradigm in two subgroups of depressed patients (retarded and blunted affect versus anxious-agitated and impulsive) compared to controls. Two results are common to all depressed patients: a slow encoding of stimuli (P1 wave) and a prolonged processing of stimulus-response compatibility (after P3b). This is compensated by a global velocity increase in stimulus evaluation or decision making (P3b) in anxious-agitated patients or, on the contrary, cumulated with its velocity decrease in retarded-blunted-affect patients. Such results could provide an explanation for the massive retardation observed in blunted-affect patients, contrary to anxious-agitated patients, whose normal reaction times may come from a very high energetical involvement at the P3b level. Results as a whole suggest that impairments in blunted-affect patients concern effort mechanisms, whereas those in anxious-agitated patients concern perceptual processes.