Auditory event related potentials in major depression: prolonged P300 latency and increased P200 amplitude

Neurofeedback Reduces P300 Amplitudes to Intensely Emotive Pictures in Depressed Cancer Patients

Objective. Electroencephalographic neurofeedback (EEG NF) or its effects on event-related potentials (ERPs) in quantitative EEG have not yet been systematically studied in cancer patients. The aim of this study was to investigate the emotional arousal and valence effects on the event-related P300 in a visual oddball paradigm by an individualized EEG alpha and theta/beta NF intervention in cancer patients and survivors (N = 18, age between 31 and 73 years). Methods. ERPs to low and high arousal target stimuli with either emotional positive or negative content and depressive state were obtained in cancer patients before and after a five-week NF intervention in a waitlist paradigm, following the consensus on the reporting and experimental design of clinical and cognitive-behavioral NF studies (CRED-nf checklist). Results. Overall, P300 amplitudes decreased significantly (p < .05) from pre to post therapy. Effects concerning high arousal stimuli with negative and positive valences were on the border to significance. Moreover, patients achieved significant relief of depressive symptoms (p < .05). Especially younger participants (<55 yrs.) benefited. Conclusions. P300 observations could reflect a therapeutic effect on brain activity level. EEG NF alleviates depressive symptoms in cancer patients. Significance. Based on these findings, further studies are needed to investigate the effects on event-related potentials by NF therapy.

Neurophysiological Signatures of Major Depressive Disorder and Frontocentral Gamma Auditory Response Deficits

Background: Aberrant gamma oscillations in major depressive disorder (MDD) have attracted extensive attention, but evidence delineating such neural signatures is lacking. The auditory steady-state response (ASSR) elicited by periodic auditory stimuli is a robust probe of gamma oscillations. Here, we sought to characterize early transient auditory evoked responses (AEPs) and sustained gamma ASSRs in MDD, thereby identifying reliable neurophysiological signatures and providing preliminary interpretations of gamma auditory response deficits in MDD. Methods: Electroencephalographic data were obtained from 40 first-episode drug-naïve patients with MDD and 41 demographically matched healthy controls (HCs) during a 40-Hz ASSR paradigm, encompassing two periodic stimuli-chirp and click stimuli. Source analysis of transient AEPs was performed to identify generators involved in early information processing dysfunction. In addition, spectrotemporal and spatial characteristics of 40-Hz ASSRs were analyzed using event-related spectral perturbation, inter-trial phase coherence, and functional connectivity index. Results: Compared to HCs, patients showed a reduced P200 amplitude that was source-localized to the middle temporal gyrus, possibly reflecting an underlying impairment in the processes of early allocation or auditory information perception within the auditory pathways. Meanwhile, attenuated 40-Hz power and phase coherence, in conjunction with suppressed right frontotemporal and frontocentral connectivity, were observed in MDD, highlighting the multidimensional entrained gamma inhibition. Correlation analyses revealed that the decreased right frontocentral connectivity was strongly related to increased anxiety severity. Importantly, these abnormalities correlated with the patient's symptoms were only found with the chirp stimulus, suggesting that the chirp stimulus has tremendous potential to reveal specific neurophysiological signatures of MDD. Conclusions: Our data reveal impaired gamma auditory responses in first-episode drug-naïve patients with MDD and suggest that right frontocentral connectivity elicited by the chirp stimulus may represent a promising signature for predicting clinical symptoms.

Association Between Early Childhood P300 Deficits and Risk for Preadolescence Depressive Disorder Mediated by Responsiveness to PCIT-ED Treatment

Preschool-onset major depressive disorder (PO-MDD) is an impairing pediatric mental health disorder that impacts children as young as three years old. There is limited work dedicated to uncovering neural measures of this early childhood disorder which could be leveraged to further understand both treatment responsiveness and future depression risk. Event-related potentials (ERPs) such as the P300 have been employed extensively in adult populations to examine depression-related deficits in cognitive and motivational systems. Few studies examine the prospective relationships between depression and P300, especially in young children. Moreover, limited research examines the relationship between P300 with psychotherapy treatment responsiveness in youths. The current study sought to examine the prospective relationships between pre-intervention P300 (i.e., choice-locked) elicited from the doors task in depressed preschool children (i.e., PO-MDD; ages 3-to-6) with reductions in depressive symptoms after completing an 18-week long dyadic psychotherapy intervention (n = 59). We also explored relations to risk for depression assessed at a follow-up visit during preadolescence (ages 8-to-12; n = 82). Those with PO-MDD exhibiting reduced choice (doors)-locked P300 demonstrated worse treatment response to psychotherapy and were more likely to meet criteria for depression during preadolescence. Moreover, the relationship between pre-intervention P300 and later preadolescence depression was significantly mediated by response to treatment. These findings suggest that deficits in brain systems linked to the choice-locked P300 component (i.e., cognitive and motivational) might be indicative of non-responsiveness to early dyadic psychotherapeutic intervention efforts for depression which impacts risk for recurrent patterns of depression in youths.

Changes in P300 amplitude to negative emotional stimuli correlate with treatment responsiveness to sertraline in adolescents with depression

OBJECTIVE

Adolescents with depression is characterized by high rates of recurrence and functional impairment, with a significant association with suicide risk. Antidepressants are commonly prescribed to treat depression, yet few reproducible neurobiological markers for depression and antidepressant treatment response have been identified. Therefore, discovering a stable and reliable neurobiological marker holds significant value for both the clinical diagnosis and treatment of depression in adolescents.

METHODS

One hundred and seven patients with major depressive disorder (MDD group, 30 males, 77 females, mean age: 14.80 years), and 25 healthy subjects (HC group, 13 males, 12 females, mean age: 15.72 years) were recruited to perform a two-choice oddball task related to negative emotional cues. All participants completed a self-administered questionnaire to gather demographic information. A trained psychiatrist administered the Hamilton Depression Scale (HAMD-17) to assess depression severity. Of the 107 adolescents with depression, 61 received antidepressant medication for 8 weeks, and 61 of these patients were followed up. Multichannel EEG was recorded continuously from 64 scalp electrodes using the Curry 8 system. EEG signal preprocessing and analysis was performed offline using the EEGLAB toolbox in MATLAB. The ERP component characteristics associated with emotional processing were extracted from the difference waves and statistically analyzed.

RESULTS

Adolescents with depression exhibited significantly larger P300 amplitudes than healthy controls in response to both neutral and negative emotional cues. Following sertraline treatment, both depression scores and P300 amplitudes decreased significantly in adolescents with depression. Moreover, a strong positive correlation was observed between changes in depression scores and changes in P300 amplitude in response to negative emotional cues before and after treatment.

CONCLUSIONS

Changes in neural reactivity to negative emotional stimuli among adolescents with depression can be selectively modulated by sertraline and are significantly associated with improvements in depressive symptoms.

SIGNIFICANCE

Changes in P300 amplitude to negative emotional stimuli significantly correlate with treatment responsiveness to sertraline in adolescents with depression.

Differences in Children and Adolescents with Depression before and after a Remediation Program: An Event-Related Potential Study

Depression is clinically diagnosed when a defined constellation of symptoms manifests over a specific duration with notable severity. According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), Major Depressive Disorder (MDD) is characterized by the presence of five or more symptoms persisting for at least two weeks. As a profound mental health condition affecting millions globally, depression presents a considerable challenge for researchers and clinicians alike. In pediatric and adolescent populations, depression can precipitate adverse outcomes, including substance abuse, academic difficulties, risky sexual behaviors, physical health problems, impaired social relationships, and a markedly elevated risk of suicide-up to thirty times higher than the general population. This paper details a study that evaluated the efficacy of Cognitive Behavioral Therapy (CBT) alone vs. CBT combined with selective serotonin reuptake inhibitors (SSRIs) in a treatment program. The study cohort comprised sixteen (16) children and adolescents diagnosed with depression (eight males and eight females) and sixteen (16) typically developing peers (eight males and eight females) aged from 9 to 15 years (Mean age = 11.94, standard deviation = 2.02). Initial assessments employed Event-Related Potentials (ERPs), the Children's Depression Inventory (CDI), and reaction time measurements. The results reveal that participants with depression exhibit cognitive deficits in attention and memory, as evidenced by prolonged P300 latencies. Following intervention with either CBT alone or CBT combined with medication, the depressed participants demonstrated significant improvements, evidenced by lower CDI scores, reduced P300 latencies, and faster reaction times, both compared to their pre-treatment status and relative to the control group.

P300 parameters in major depressive disorder: A systematic review and meta-analysis

OBJECTIVES

Event-related potential measures have been extensively studied in mental disorders. Among them, P300 amplitude and latency reflect impaired cognitive abilities in major depressive disorder (MDD). The present systematic review and meta-analysis was conducted to investigate whether patients with MDD differ from healthy controls (HCs) with respect to P300 amplitude and latency.

METHODS

PubMed and Web of Science databases were searched from inception to 15 January 2023 for case-control studies comparing P300 amplitude and latency in patients with MDD and HCs. The primary outcome was the standard mean difference. A total of 13 articles on P300 amplitude and latency were included in the meta-analysis.

RESULTS

Random effect models indicated that MDD patients had decreased P300 amplitude, but similar latency compared to healthy controls. According to regression analysis, the effect size increased with the severity of depression and decreased with the proportion of women in the MDD samples. Funnel plot asymmetry was not significant for publication bias.

CONCLUSIONS

Decreased P300 amplitude may be a candidate diagnostic biomarker for MDD. However, prospective studies testing P300 amplitude as a monitoring biomarker for MDD are needed.

Effects of Lacticaseibacillus paracasei Strain Shirota on Daytime Performance in Healthy Office Workers: A Double-Blind, Randomized, Crossover, Placebo-Controlled Trial

Lacticaseibacillus paracasei strain Shirota (LcS) modulates psychological homeostasis via the gut-brain axis. To explore the possible efficacy of LcS for improving daytime performance, we conducted a double-blind, randomized, crossover, placebo-controlled study of 12 healthy office workers with sleep complaints. The participants received fermented milk containing viable LcS (daily intake of 1 × 1011 colony-forming units) and non-fermented placebo milk, each for a 4-week period. In the last week of each period, the participants underwent assessments of their subjective mood and measurements of physiological state indicators via an electroencephalogram (EEG) and heart rate variability in the morning and afternoon. The attention score in the afternoon as assessed by the visual analog scale was higher in the LcS intake period than in the placebo intake period (p = 0.041). Theta power on EEG measured at rest or during an auditory oddball task in the afternoon was significantly lower in the LcS period than in the placebo period (p = 0.025 and 0.009, respectively). The change rate of theta power was associated with the change in attention score. Treatment-associated changes were also observed in heart rate and the sympathetic nerve activity index. These results indicate that LcS has possible efficacy for improving daytime performance, supported by observations of the related physiological state indicators.

Electrophysiological biomarkers and age characterize phenotypic heterogeneity among individuals with major depressive disorder

Introduction: Despite the high need for effective treatments for major depressive disorder (MDD), the development of novel medicines is hampered by clinical, genetic and biological heterogeneity, unclear links between symptoms and neural dysfunction, and tenuous biomarkers for clinical trial contexts of use. Methods: In this study, we examined the International Study to Predict Optimized Treatment in Depression (iSPOT-D) clinical trial database for new relationships between auditory event-related potential (ERP) responses, demographic features, and clinical symptoms and behavior, to inform strategies for biomarker-driven patient stratification that could be used to optimize future clinical trial design and drug development strategy in MDD. Results: We replicate findings from previous analyses of the classic auditory oddball task in the iSPOT-D sample showing smaller than typical N1 and P300 response amplitudes and longer P300 latencies for target and standard stimuli in patients with MDD, suggesting altered bottom-up sensory and top-down attentional processes. We further demonstrate that age is an important contributor to clinical group differences, affecting both topographic distribution of the clinically informative ERP responses and the types of the stimuli sensitive to group differences. In addition, the observed brain-behavior associations indicate that levels of anxiety and stress are major contributing factors to atypical sensory and attentional processing among patients with MDD, particularly in the older subgroups. Discussion: Our novel findings support the possibility of accelerated cognitive aging in patients with MDD and identify the frontal P300 latency as an additional candidate biomarker of MDD. These results from a large, well-phenotyped sample support the view that heterogeneity of the clinical population with MDD can be systematically characterized based on age and neural biomarkers of sensory and attentional processing, informing patient stratification strategies in the design of clinical trials.

Auditory event-related potentials in separating patients with depressive disorders and non-depressed controls: A narrative review

This narrative review brings together the findings regarding the differences in the auditory event-related potentials (ERPs) between patients with depressive disorder and non-depressed control subjects. These studies' results can inform us of the possible alterations in sensory-cognitive processing in depressive disorders and the potential of using these ERPs in clinical applications. Auditory P3, mismatch negativity (MMN) and loudness dependence of auditory evoked potentials (LDAEP) were the subjects of the investigation. A search in PubMed yielded 84 studies. The findings of the reviewed studies were not highly consistent, but some patterns could be identified. For auditory P3b, the common findings were attenuated amplitude and prolonged latency among depressed patients. Regarding auditory MMN, especially the amplitude of duration deviance MMN was commonly attenuated, and the amplitude of frequency deviance MMN was increased in depressed patients. In LDAEP studies, generally, no differences between depressed patients and non-depressed controls were reported, although some group differences concerning specific depression subtypes were found. This review posits that future research should investigate whether certain stimulus conditions are particularly efficient at separating depressed and non-depressed participant groups. Future studies should contrast responses in different subpopulations of depressed patients, as well as different clinical groups (e.g., depressive disorder and anxiety disorder patients), to investigate the specificity of the auditory ERP alterations for depressive disorders.

Cognitive impairment in the co-occurrence of alcohol dependence and major depression: neuropsychological assessment and event-related potentials analyses

To evaluate the putative detrimental effect of Major Depressive Disorder (MDD) on the cognitive impairment associated with Alcohol Dependence (AD), we contrasted the neuropsychological profile and behavioral responses of AD subjects, MDD individuals, and in those with a co-occurring AD-MDD diagnosis (DD). Patients and healthy subjects completed a comprehensive neuropsychological battery and were recorded for P200, P300, and N450 event-related potentials during memory and Stroop tasks. AD subjects exhibited a generalized detrimental neuropsychological performance; in contrast, in MDD individuals, impairment was limited to discrete domains. Notably, the deficits were distinctive in DD cases. A P200 increased amplitude in MDD, a decrease in P300 amplitude in AD, and increased latency of P300 in DD patients were the overt electrophysiological abnormalities identified. Dual patients also exhibited a distinct pattern of behavioral responses, particularly apparent during high-demand cognitive tasks. Specific ERP adjustments were associated with the short-term fluoxetine treatment in DD and MDD subjects; the SSRI also improved altered baseline performance in learning and cognitive flexibility in DD subjects. In conclusion, the neuropsychological and behavioral alterations detected in the co-occurrence of AD-MDD did not seem to be merely the sum of the negative contributions of the independent disorders.

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Dual diagnosis (DD) patients exhibited a distinctive pattern of cognitive impairments compared to single diagnosis subjects.

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The ERP alterations identified were not shared among affected groups.

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Dual patients exhibited idiosyncratic behavioral responses.

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Impaired executive functions in DD subjects improved with SSRI medication.

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Neuropsychological and behavioral alterations are not explained as the sum of negative contributions of individual diagnosis.

Association Between the Visual N1-P2 Complex and Neuroticism

Neuroticism is a personality trait associated with impaired attention, memory, and error detection. Thus, the present study investigated the visual N100 and P200 event-related potentials components associated with attention using a 2-back working memory task in healthy neurotic and nonneurotic participants, evaluated using the Neuroticism, Extraversion, Openness Five Factor Inventory. A total of 35 healthy participants were asked to perform the 2-back task while recording electroencephalographic activity from 64 electrodes on the scalp. Analysis of the N100 and P200 amplitude and latency in high neuroticism and low neuroticism subjects showed an increased P200 amplitude and latency for high neuroticism subjects in the frontal and parietal regions, respectively. However, there were no significant performance differences between the high and low neuroticism subjects for the 2-back working memory task. Therefore, the results suggest that neuroticism is associated with the P200 component elicited in the context of a working memory task.

Behavioural and neurophysiological differences in working memory function of depressed patients and healthy controls

OBJECTIVE

Major depressive disorder (MDD) is associated with deficits in working memory. Several cognitive subprocesses interact to produce working memory, including attention, encoding, maintenance and manipulation. We sought to clarify the contribution of functional deficits in these subprocesses in MDD by varying cognitive load during a working memory task.

METHODS

41 depressed participants and 41 age and gender-matched healthy controls performed the n-back working memory task at three levels of difficulty (0-, 1-, and 2-back) in a pregistered study. We assessed response times, accuracy, and event-related electroencephalography (EEG), including P2 and P3 amplitudes, and frontal theta power (4-8 Hz).

RESULTS

MDD participants had prolonged response times and more positive frontal P3 amplitudes (i.e., Fz) relative to controls, mainly in the most difficult 2-back condition. Working memory accuracy, P2 amplitudes and frontal theta event-related synchronisation did not differ between groups at any level of task difficulty.

CONCLUSIONS

Depression is associated with generalized psychomotor slowing of working memory processes, and may involve compensatory hyperactivity in frontal and parietal regions.

SIGNIFICANCE

These findings provide insights into MDD working memory deficits, indicating that depressed individuals dedicate greater levels of cortical processing and cognitive resources to achieve comparable working memory performance to controls.

Relationship Match: The Neural Underpinnings of Social Feedback in Romantic Couples

Romantic love involves an evaluative process in which couples weigh similarities and differences that facilitates pair bonding. We investigated neural attentive processes (P3) during evaluative relationship feedback within existing romantic couples using the Relationship Match Game. This paradigm included participant-driven expectations about relationship matching and relationship feedback from an expert panel of fictive peers and their romantic partner. In total, 49 couples participated who had dated less than one year. Participants showed significantly larger P3s in anticipation of feedback when they expected a mismatch, especially when supported by panel feedback. P3 amplitudes were also greater when participants received feedback from their partner congruent with their own assessment of compatibility. This was moderated by relational ambiguity, or one’s preference to keep the relationship’s status vague. We discuss how insecurity about the relationship is costly in terms of attentional resources contributing to over-alertness to cues of relationship evaluation.

The reduced left hippocampal volume related to the delayed P300 latency in amnestic mild cognitive impairment

BACKGROUND

Amnestic mild cognitive impairment (aMCI) is characterized by delayed P300 latency and reduced grey matter (GM) volume, respectively. The relationship between the features in aMCI is unclear. This study was to investigate the relationship between the altered P300 latency and the GM volume in aMCI.

METHODS

Thirty-four aMCI and 34 well-matched normal controls (NC) were studied using electroencephalogram during a visual oddball task and scanned with MRI. Both tests were finished in the same day.

RESULTS

As compared with the NC group, the aMCI group exhibited delayed P300 latency in parietal cortex and reduced GM volumes in bilateral temporal pole and left hippocampus/parahippocampal gyrus. A remarkable negative correlation was found between delayed P300 latency and reduced left hippocampal volume only in the aMCI group. Interestingly, the mediating analysis found P300 latency significantly mediated the association between right supramarginal gyrus volume and information processing speed indicated by Stroop Color and Word Test A scores.

CONCLUSIONS

The association between delayed P300 latency and reduced left hippocampal volume in aMCI subjects suggests that reduced left hippocampal volume may be the potential structural basis of delayed P300 latency.

A reduced P300 prospectively predicts increased depressive severity in adults with clinical depression

Neurocognitive impairments commonly observed in depressive disorders are thought to be reflected in reduced P300 amplitudes. To date, depression-related P300 amplitude reduction has mostly been demonstrated cross-sectionally, while its clinical implication for the course of depression remains largely unclear. Moreover, the relationship between P300 and specific clinical characteristics of depression is uncertain. To shed light on the functional significance of the P300 in depression, we examined whether initial P300 amplitude prospectively predicted changes in depressive symptoms among a community sample of 58 adults (mean age = 38.86 years old, 81% female) with a current depressive disorder. This sample was assessed at two-time points, separated by approximately nine months (range = 6.6-15.9). At the initial visit, participants completed clinical interviews, self-report measures, and a flanker task, while EEG was recorded to derive P300 amplitude. At the follow-up visit, participants again completed the same clinical interviews and self-report measures. Results indicated that a reduced P300 amplitude at the initial visit was associated with higher total depressive symptoms at follow-up, even after controlling for initial depressive symptoms. These data indicate the potential clinical utility for the P300 as a neural marker of disease course among adults with a current depressive disorder. Future research may target P300 in interventions to determine whether depression-related outcomes can be improved.

MMN-Indexed Auditory Change Detection in Major Depressive Disorder

In major depressive disorder (MDD), event-related potentials that are involved in auditory cortex function (i.e. N100 and P300) often have greater latencies and decreased amplitudes. The auditory mismatch negativity (MMN) is thought to be produced by generators in the auditory cortex, as well as the frontal lobes. Reports on differences in MMN in those with MDD have been varied. It was hypothesized that the wide range of results in the literature may be due to the use of different deviant types in eliciting the MMN. To attempt and explain these inconsistencies, the current study employed a multifeature MMN paradigm with 5 deviant tone types in community-dwelling participants with a diagnosis of MDD. We found those with MDD had higher MMN amplitudes following tones that deviated in intensity and location, but no difference in MMNs elicted by the other deivants (relative to unaffected controls). Location MMN deviants were negatively correlated with depression severity scores (i.e. larger MMN with greater severity). We also found longer MMN latencies following the pitch deviant. These results suggest the early auditory change detection process is altered in MDD, but only following certain types of auditory stimuli. Potential explanations for these findings, including high levels of anxiety and the influence of tryptophan are explored. Equally, the current report highlights the importance of using various deviant types when examining the MMN in clinical populations.

Staging model in psychiatry: Review of the evolution of electroencephalography abnormalities in major psychiatric disorders

AIM

Clinical staging in psychiatry aims to classify patients according to the severity of their symptoms, from stage 0 (increased risk, asymptomatic) to stage 4 (severe illness), enabling adapted treatment at each stage of the illness. The staging model would gain specificity if one or more quantifiable biological markers could be identified. Several biomarkers reflecting possible causal mechanisms and/or consequences of the pathophysiology are candidates for integration into the clinical staging model of psychiatric illnesses.

METHODS

This review covers the evolution (from stage 0 to stage 4) of the most important brain functioning impairments as measured with electroencephalography (EEG), in psychosis spectrum and in severe mood disorders.

RESULTS

The present review of the literature demonstrates that it is currently not possible to draw any conclusion with regard to the state or trait character of any of the EEG impairments in both major depressive disorder and bipolar disorder. As for schizophrenia, the most promising markers of the stage of the illness are the pitch mismatch negativity as well as the p300 event-related potentials, as these components seem to deteriorate with increasing severity of the illness.

CONCLUSIONS

Given the complexity of major psychiatric disorders, and that not a single impairment can be observed in all patients, future research should most likely consider combinations of markers in the quest for a better identification of the stages of the psychiatric illnesses.

Machine-learning-based classification between post-traumatic stress disorder and major depressive disorder using P300 features

BACKGROUND

The development of optimal classification criteria for specific mental disorders which share similar symptoms is an important issue for precise diagnosis. We investigated whether P300 features in both sensor-level and source-level could be effectively used to classify post-traumatic stress disorder (PTSD) and major depressive disorder (MDD).

METHOD

EEG signals were recorded from fifty-one PTSD patients, 67 MDD patients, and 39 healthy controls (HCs) while performing an auditory oddball task. Amplitude and latency of P300 were evaluated, and the current source analysis of P300 components was conducted using sLORETA. Finally, we classified two groups using machine-learning methods with both sensor- and source-level features. Moreover, we checked the comorbidity effects using the same approaches (PTSD-mono diagnosis (PTSDm, n = 28) and PTSD-comorbid diagnosis (PTSDc, n = 23)).

RESULTS

PTSD showed significantly reduced P300 amplitudes and prolonged latency compared to HCs and MDD. Moreover, PTSD showed significantly reduced source activities, and the source activities were significantly correlated with symptoms of depression and anxiety. Also, the best classification accuracy at each pair was as follows: 80.00% (PTSD-HCs), 67.92% (MDD-HCs), 70.34% (PTSD-MDD), 82.09% (PTSDm-HCs), 71.58% (PTSDm-MDD), 82.56% (PTSDc-HCs), and 76.67% (PTSDc- MDD).

CONCLUSION

Since abnormal P300 reflects pathophysiological characteristics of PTSD, PTSD patients were well-discriminated from MDD and HCs when using P300 features. Thus, altered P300 characteristics in both sensor- and source-level may be useful biomarkers to diagnosis PTSD.

Simple Electroencephalographic Treatment-Emergent Marker Can Predict Repetitive Transcranial Magnetic Stimulation Antidepressant Response-A Feasibility Study

OBJECTIVES

Prefrontal repetitive transcranial magnetic stimulation (rTMS) repeated daily for 4 to 6 weeks is used to treat major depressive disorder, but more than 50% of patients do not achieve significant response. Here we test the validity of a simple electroencephalographic (EEG) marker that predicts nonresponse to rTMS. Such a marker could potentially increase rTMS effectiveness by directing nonresponders to alternative treatments or by guiding early modification of stimulation parameters.

METHODS

We retrospectively analyzed 2-channel EEG data captured in the OPT-TMS National Institute of Mental Health-sponsored, multicenter study. Cumulative Brain Engagement Index (cBEI), a measure derived from template matching that allows scoring EEG dynamics along treatment, was computed.

RESULTS

Six hundred sixty-five EEG recordings were analyzed. In the rTMS group, the median cBEI was found to increase in the responder group but remained unchanged in the nonresponder group. The difference between the cBEI of the groups became statistically significant by the third valid EEG sample. Within 5 samples, 91% of the responders presented with a cBEI above a preset threshold. Within 9 samples, 17% of the nonresponders had a cBEI above the threshold.

CONCLUSIONS

This study demonstrates the feasibility of a simple-to-capture EEG marker as a treatment-emergent marker of response to rTMS treatment of depression. In the OPT-TMS study, discontinuing treatment when the cBEI dropped below the threshold between the fifth to ninth treatment potentially could have avoided administration of 485 (63%) of 765 treatments. Because the marker can be generated online, it would be of interest to evaluate, in future studies, whether it could be used to tune treatment parameters and improve remission rates.

The P300 component decreases in a bimodal oddball task in individuals with depression: An event-related potentials study

OBJECTIVE

In this study, we investigated auditory-visual stimulation-induced P300 and examined whether P300 was differentially modulated between individuals with clinical depression and healthy controls. We hypothesized that the P300 component would significantly differ between individuals with depression and healthy individuals Specifically, we predicted that the P300 component induced by the bimodal oddball task would be significantly different from that induced by the unimodal task.

METHODS

Forty-five individuals with depression and forty-five healthy controls participated in this study. All participants were instructed to complete three oddball tasks-auditory (A), visual (V), and bimodal (AV)-while their electroencephalographic signals were recorded.

RESULTS

Individuals with depression had a lower P300 amplitude and a longer latency than controls in the bimodal task. P300 amplitudes in the bimodal task were significantly higher than in the auditory or visual tasks in both groups. In the depression group, the P300 amplitude was negatively correlated with Hamilton Depression Rating Scale (HAM-D) scores in the bimodal task.

CONCLUSIONS

Our results, which agree with those reported previously, suggest that there is a heightened P300 amplitude sensitivity in the bimodal task in individuals with depression. Our data also suggest that P300 amplitudes in the bimodal task may reflect the severity of depression.

SIGNIFICANCE

The reduced task-related ERP response in individuals with depression suggests significant impairments in these individuals in stimulus integration and response functions.

Uncensored EEG: The role of DC potentials in neurobiology of the brain

Brain direct current (DC) potentials denote sustained shifts and slow deflections of cerebral potentials superimposed with conventional electroencephalography (EEG) waves and reflect alterations in the excitation level of the cerebral cortex and subcortical structures. Using galvanometers, such sustained displacement of the EEG baseline was recorded in the early days of EEG recordings. To stabilize the EEG baseline and eliminate artefacts, EEG was performed later by voltage amplifiers with high-pass filters that dismiss slow DC potentials. This left slow DC potential recordings as a neglected diagnostic source in the routine clinical setting over the last few decades. Brain DC waves may arise from physiological processes or pathological phenomena. Recordings of DC potentials are fundamental electro-clinical signatures of some neurological and psychological disorders and may serve as diagnostic, prognostic, and treatment monitoring tools. We here review the utility of both physiological and pathological brain DC potentials in different aspects of neurological and psychological disorders. This may enhance our understanding of the role of brain DC potentials and improve our fundamental clinical and research strategies for brain disorders.

P3b amplitude is not reduced in abstinent alcoholics with a current MDD

BACKGROUND AND AIMS

In two studies of long-term abstinent alcoholics (LTAAs), we found that about 17% had a current major depressive disorder (MDD). We tested the hypothesis that LTAAs with a current MDD diagnosis do not exhibit the reduced P3b event-related potential amplitude endophenotype for alcoholism. This is consistent with the majority of LTAAs with a current MDD having developed alcohol dependence via self-medication of their MDD rather than their alcohol dependence arising from the alcoholism endophenotype. We revisited the P3b data from the two LTAAs studies, comparing LTAAs with a current MDD vs. LTAAs without a current MDD to each other and to non-substance abusing controls (NSACs). In northern California, 48 LTAAs and 48 non-substance abusing controls were studied, while in Honolulu, 105 LTAAs and 77 NSACs were studied. A total of 26 LTAAs had a current MDD (10 in California and 16 in Honolulu). The difference in P3b amplitude and latency (measured in targets-standards) in a 3-condition visual oddball paradigm was compared to MDD diagnoses gathered using the computerized Diagnostic Interview Schedule. Across both study sites, LTAAs without a current MDD (either with no lifetime MDD or a lifetime, but not current MDD) had lower P3b amplitudes than NSACs. In contrast, P3b amplitudes in LTAAs with a current MDD did not differ from controls. We conclude that alcohol dependence in LTAAs with a current MDD did not derive from the alcoholism endophenotype. This group may not exhibit the externalizing diathesis characterized by impulsive, disinhibited behavior and may have developed alcohol dependence via excessive drinking in an attempt to self-medicate their MDD. These results have major implications for targeted treatments of alcoholism and comorbid MDD.

Personalized Medicine: Review and Perspectives of Promising Baseline EEG Biomarkers in Major Depressive Disorder and Attention Deficit Hyperactivity Disorder

Personalized medicine in psychiatry is in need of biomarkers that resemble central nervous system function at the level of neuronal activity. Electroencephalography (EEG) during sleep or resting-state conditions and event-related potentials (ERPs) have not only been used to discriminate patients from healthy subjects, but also for the prediction of treatment outcome in various psychiatric diseases, yielding information about tailored therapy approaches for an individual. This review focuses on baseline EEG markers for two psychiatric conditions, namely major depressive disorder and attention deficit hyperactivity disorder. It covers potential biomarkers from EEG sleep research and vigilance regulation, paroxysmal EEG patterns and epileptiform discharges, quantitative EEG features within the EEG main frequency bands, connectivity markers and ERP components that might help to identify favourable treatment outcome. Further, the various markers are discussed in the context of their potential clinical value and as research domain criteria, before giving an outline for future studies that are needed to pave the way to an electrophysiological biomarker-based personalized medicine.

A Possible Common Neurophysiologic Basis for MDD, Bipolar Disorder, and Schizophrenia: Lessons from Electrophysiology

There is ample electrophysiological evidence of attention dysfunction in the EEG/ERP signal of major depressive disorder (MDD), bipolar disorder, and schizophrenia. The reduced attention-related ERP waves show much similarity between MDD, bipolar disorder, and schizophrenia, raising the question whether there are similarities in the neurophysiologic process that underlies attention dysfunction in these pathologies. The present work suggests that there is such a unified underlying neurophysiologic process, which results in reduced attention in the three pathologies. Naturally, as these pathologies involve different clinical manifestations, we expect differences in their underlying neurophysiology. These differences and their subtle manifestation in the ERP marker for attention are also discussed. MDD, bipolar disorder, and schizophrenia are just three of multiple neuropsychiatric disorders, which involve changes in the EEG/ERP manifestations of attention. Further work should expand the basic model presented here to offer comprehensive modeling of these multiple disorders and to emphasize similarities and dissimilarities of the underlying neurophysiologic processes.

The role of P300 event-related potentials in the cognitive recovery after the stroke

The aim of this study was to elucidate the effects of an ischemic stroke on the amplitude and latency of the P300 wave and evaluate their changes over a prospective 1-year follow-up period. We recorded the P300 wave using an auditory oddball paradigm in 60 consecutive brain infarct patients at baseline (i.e., within 4 weeks after the stroke), after 3 months, after 12 months and in 30 healthy control subjects. The P300 latencies in stroke patients were significantly longer and the P300 amplitudes were significantly smaller than those of the control group. The latency of P300 showed a highly significant average improvement 12 months after the stroke compared to the baseline. There was no significant change observed for the P300 amplitude during the same period. The P3 latency is initially more increased in the patients with hemispheric brain infarction but shows a better recovery compared to the patients with brainstem infarction. Also, the results of the P300 latency of patients with the left-sided lesions was significantly longer compared to the patients with right-sided lesions on the beginning of the study but not 3 and 12 months after the stroke. The results of our study show the importance of P300 event-related potentials in the detection and follow-up of cognitive changes after ischemic stroke.

Utility of event-related potentials in predicting antidepressant treatment response: An iSPOT-D report

It is essential to improve antidepressant treatment of major depressive disorder (MDD) and one way this could be achieved is by reducing the number of treatment steps by employing biomarkers that can predict treatment outcome. This study investigated differences between MDD patients and healthy controls in the P3 and N1 component from the event-related potential (ERP) generated in a standard two-tone oddball paradigm. Furthermore, the P3 and N1 are investigated as predictors for treatment outcome to three different antidepressants. In the international Study to Predict Optimized Treatment in Depression (iSPOT-D)--a multi-center, international, randomized, prospective practical trial--1008 MDD participants were randomized to escitalopram, sertraline or venlafaxine-XR. The study also recruited 336 healthy controls. Treatment response and remission were established after eight weeks using the 17-item Hamilton Rating Scale for Depression. P3 and N1 latencies and amplitudes were analyzed using a peak-picking approach and further replicated by using exact low resolution tomography (eLORETA). A reduced P3 was found in MDD patients compared to controls by a peak-picking analysis. This was validated in a temporal global field power analysis. Source density analysis revealed that the difference in cortical activity originated from the posterior cingulate and parahippocampal gyrus. Male non-responders to venlafaxine-XR had significantly smaller N1 amplitudes than responders. This was demonstrated by both analytical methods. Male non-responders to venlafaxine-XR had less activity originating from the left insular cortex. The observed results are discussed from a neural network viewpoint.

Auditory event-related potentials in methadone substituted opiate users

The effects of methadone maintenance treatment (MMT) on neurophysiological function are unclear. Using an auditory oddball paradigm, event-related potential (ERP) amplitudes and latencies were measured in 32 patients undertaking MMT, 17 opiate users who were addicted but not receiving substitution treatment and 25 healthy control subjects. Compared with healthy control subjects, the MMT and opiate user groups showed an increased P200 amplitude in response to target stimuli. The opiate user group also exhibited a decreased amplitude and an increased latency of N200, and a greater number of task-related errors than either healthy control subjects or patients undertaking MMT. There were no significant group differences in the P300 amplitude. However, it is noteworthy that the frontal P300 amplitude of the MMT group was greater than that of opiate users or healthy controls. Our findings suggest that altered sensory information processing associated with a history of opiate use remains in patients undertaking MMT. However, there are less marked ERP abnormalities in those receiving MMT than in active opiate users. The deficits in information processing associated with illicit opiate use are likely to be reduced during MMT.

Auditory selective attention in adolescents with major depression: An event-related potential study

BACKGROUND

Major depression (MD) is associated with deficits in selective attention. Previous studies in adults with MD using event-related potentials (ERPs) reported abnormalities in the neurophysiological correlates of auditory selective attention. However, it is yet unclear whether these findings can be generalized to MD in adolescence. Thus, the aim of the present ERP study was to explore the neural mechanisms of auditory selective attention in adolescents with MD.

METHODS

24 male and female unmedicated adolescents with MD and 21 control subjects were included in the study. ERPs were collected during an auditory oddball paradigm.

RESULTS

Depressive adolescents tended to show a longer N100 latency to target and non-target tones. Moreover, MD subjects showed a prolonged latency of the P200 component to targets. Across groups, longer P200 latency was associated with a decreased tendency of disinhibited behavior as assessed by a behavioral questionnaire.

LIMITATIONS

To be able to draw more precise conclusions about differences between the neural bases of selective attention in adolescents vs. adults with MD, future studies should include both age groups and apply the same experimental setting across all subjects.

CONCLUSIONS

The study provides strong support for abnormalities in the neurophysiolgical bases of selective attention in adolecents with MD at early stages of auditory information processing. Absent group differences in later ERP components reflecting voluntary attentional processes stand in contrast to results reported in adults with MD and may suggest that adolescents with MD possess mechanisms to compensate for abnormalities in the early stages of selective attention.

Differences in early and late stages of information processing between slow versus fast participants

The human brain is a system consisting of various interconnected neural networks, with functional specialization coexisting with functional integration occurring both; temporally and spatially at many levels. The current study ranked and compared fast and slow participants in processing information by assessing latency and amplitude of early and late Event-Related Potential (ERP) components, including P200, N200, Premotor Potential (PMP) and P300. In addition, the Reaction Time (RT) of participants was compared and related to the respective ERP components. For this purpose, twenty right-handed and healthy individuals were subjected to a classical ERP “Oddball” paradigm. Principal Component Analysis (PCA) and Discriminant Function analyses (DFA) used PRE components and the Reaction Time (RT) to classify individuals. Our results indicate that latencies of P200 (O2 electrode), N200 (O2), PMP (C3) and P300 (Pz) components are significantly reduced in the group of fast responding participants. In addition, the P200 amplitude is significantly increased in the group of fast responding participants. Based on these findings, we suggest that the ERP is able to detect even minimal impairments, in the processing of somatosensory information and cognitive and motor stages. Hence, the study of ERP might also be capable of assessing sensorimotor dysfunctions in healthy old-aged people and in neuropsychiatric patients (suffering from dementia, Parkinson’s disease, and other neurological disorders).

Pre-attentive information processing and impulsivity in bipolar disorder

Early responses to stimuli can be measured by sensory evoked potentials (EP) using repeated identical stimuli, S1 and S2. Response to S1 may represent efficient stimulus detection, while suppression of response to S2 may represent inhibition. Early responses to stimuli may be related to impulsivity. We compared EP reflecting stimulus detection and inhibition in bipolar disorder and healthy controls, and investigated relationships to impulsivity. Subjects were 48 healthy controls without family histories of mood disorder and 48 with bipolar disorder. EP were measured as latencies and amplitudes for auditory P50 (pre-attentional), N100 (initial direction of attention) and P200 (initial conscious awareness), using a paired-click paradigm, with identical stimuli 0.5 s apart. Impulsivity was measured by questionnaire and by laboratory tests for inability to suppress responses to stimuli or to delay response for a reward. Analyses used general linear models. S1 amplitudes for P50, N100, and P200, and gating of N100 and P200, were lower in bipolar disorder than in controls. P50 S1 amplitude correlated with accurate laboratory-task responding, and S2 amplitude correlated with impulsive task performance and fast reaction times, in bipolar disorder. N100 and P200 EP did not correlate with impulsivity. These findings were independent of symptoms, treatment, or substance-use history. EPs were not related to questionnaire-measured or reward-based impulsivity. Bipolar I disorder is characterized by reduced pre-attentional and early attentional stimulus registration relative to controls. Within bipolar disorder, rapid-response impulsivity correlates with impaired pre-attentional response suppression. These results imply specific relationships between ERP-measured response inhibition and rapid-response impulsivity.

Cognition in late onset depression

The aim of study was to assess cognition in patients with late onset depression in a symptom-free remission period measuring event-related potentials and reaction times (RT) in a modified computer version of the Stroop test. Thirty four patients with late-onset depression were included after they had reached remission. They were compared to age-, gender- and education-matched healthy controls. Each participant completed a single item computer version of the Stroop Color-word task using verbal response mode. EEG and RT were simultaneously recorded. RTs were significantly prolonged in patients in all conditions of the Stroop paradigm, and the interference effect was significantly greater in patients compared to controls. Results also revealed abnormal late positive Stroop related potentials in the period of about 500-600 ms period corresponding to the so-called P300b wave. Our study supports the view that patients with late onset depression are also cognitively impaired and that this impairment persists in the period of early remission. Using more sensitive ERP measurement of the Stroop task we demonstrated impaired information processing at an earlier, pre-response related stage.

Auditory P3 in antidepressant pharmacotherapy treatment responders, non-responders and controls

Event-related potentials (ERPs), derived from electroencephalographic (EEG) recordings, can index electrocortical activity related to cognitive operations. The fronto-central P3a ERP is involved in involuntary processing of novel auditory information, whereas the parietal P3b indexes controlled attention processing. The amplitude of the auditory P3b has been found to be decreased in major depressive disorder (MDD). However, few studies have examined the relations between the P3b, the related P3a, and antidepressant treatment response. We tested 53 unmedicated individuals (25 females) with MDD, as well as 43 non-depressed controls (23 females) on the novelty oddball task, wherein infrequent deviant (target) and frequent standard (non-target) tones were presented, along with infrequent novel (non-target/distractor) sounds. The P3a and P3b ERPs were assessed to novel and target sounds, respectively, as were their accompanying behavioral performance measures. Depression ratings and the antidepressant response status were assessed following 12 weeks of pharmacotherapy with three different regimens. Antidepressant treatment non-responders had smaller baseline P3a/b amplitudes than responders and healthy controls. Baseline P3b amplitude also weakly predicted the extent of depression rating changes by week 12. Females exhibited larger P3a/b amplitudes than males. With respect to task performance, controls had more target hits than treatment non-responders. ERP measures correlated with clinical changes in males and with behavioral measures in females. These results suggest that greater (or control-like) baseline P3a/b amplitudes are associated with a positive antidepressant response, and that gender differences characterize the P3 and, by extension, basic attentive processes.

EEG biomarkers in major depressive disorder: discriminative power and prediction of treatment response

Major depressive disorder (MDD) has high population prevalence and is associated with substantial impact on quality of life, not least due to an unsatisfactory time span of sometimes several weeks from initiation of treatment to clinical response. Therefore extensive research focused on the identification of cost-effective and widely available electroencephalogram (EEG)-based biomarkers that not only allow distinguishing between patients and healthy controls but also have predictive value for treatment response for a variety of treatments. In this comprehensive overview on EEG research on MDD, biomarkers that are either assessed at baseline or during the early course of treatment and are helpful in discriminating patients from healthy controls and assist in predicting treatment outcome are reviewed, covering recent decades up to now. Reviewed markers include quantitative EEG (QEEG) measures, connectivity measures, EEG vigilance-based measures, sleep-EEG-related measures and event-related potentials (ERPs). Further, the value and limitations of these different markers are discussed. Finally, the need for integrated models of brain function and the necessity for standardized procedures in EEG biomarker research are highlighted to enhance future research in this field.

Local contextual processing in major depressive disorder

OBJECTIVE

The study investigated local contextual processing in patients with major depressive disorder (MDD). This was defined as the ability to utilize predictive contextual information to facilitate detection of predictable versus random targets.

METHOD

We recorded EEG in 15 MDD patients and 14 age-matched controls. Recording blocks consisted of targets preceded by randomized sequences of standards and by sequences of standards that included a predictive sequence signaling the occurrence of a subsequent target event.

RESULTS

Both MDD patients and age-matched controls demonstrated a significant reaction time (RT) and P3b latency differences between predicted and random targets. However, patients demonstrated a specific prolongation of these measures during processing of predicted targets, as well as an attenuation of P3b amplitudes for the predictive sequence. In addition, patients target N1 amplitudes were attenuated compared with controls.

CONCLUSION

MDD patients were able to utilize predictive context in order to facilitate processing of deterministic targets, however, this ability was limited compared to controls, as demonstrated by context-dependent P3b deficits.

SIGNIFICANCE

These findings suggest that patients with major depression have altered processing of local contextual processing.

Electrocortical features of depression and their clinical utility in assessing antidepressant treatment outcome

Major depressive disorder (MDD) is primarily characterized by decreased affect and accompanying behavioural consequences, but it is also associated with cognitive dysfunction. Assessment of electroencephalographic (EEG) activity and associated event-related potentials (ERPs; derived from averaged EEG activity in response to a stimulus) in the context of MDD has provided insights into the electrocortical abnormalities associated with the disorder. Importantly, EEG and ERPs also have emerged as candidates for predicting and optimizing antidepressant (AD) treatment outcome. This is critical in light of relatively low remission rates or a limited response to initial AD interventions. In contrast to other neuroimaging approaches, EEG and ERPs may be superior for predicting and monitoring AD response, as electrocortical measures are relatively inexpensive, easy to use, and have excellent temporal (that is, millisecond) resolution, enabling fine-grained assessment of basic cognitive and emotive processes. This review aims to highlight the most consistently noted EEG and ERP features in MDD, which may one day assist with diagnostic confirmation, as well as the potential clinical utility of specific electrocortical measures in aiding with response prediction.

Neuropsychological correlates of the P300 in patients with Alzheimer's disease

OBJECTIVES

The P300 is a useful psychophysiological index that reflects cognitive functions; however, the relationship between P300 indices and neuropsychological tests in Alzheimer's disease (AD) patients is unclear.

METHODS

Thirty-one AD patients and 31 elderly normal control (NC) subjects were recruited. Age and education level were matched between the two groups. The relationship between the P300 and the Korean version of the Consortium to Establish a Registry for Alzheimer's disease (CERAD-K) assessment packet (including 11 neuropsychological tests) was examined in AD patients.

RESULTS

Compared to the NC subjects, the AD patients exhibited significantly decreased P300 amplitudes; however, there was no significant difference between the two groups in terms of P300 latency. After a permutation-based correction for multiple tests, P300 amplitudes at the Cz and Pz electrodes were significantly correlated with performance on the word list recognition, constructional praxis, and word fluency neuropsychological tests in the AD patients. Additionally, P300 latencies at the Pz and C6 electrodes were also significantly correlated with performance on the Mini-Mental State Examination, CERAD-K version (MMSE-K), and Trail Making Test part A (TMT-A) neuropsychological tests in the AD patients.

CONCLUSIONS

The results suggest that the P300 is responsive to the deterioration of language, memory, and executive functions observed in AD patients. Although there was no significant difference between the AD patients and NC subjects in the P300 latency, P300 latency has been shown to reflect impaired global cognition and attention deficits associated with AD. Our results suggest that P300 indices could be used as biological markers that indicate impaired neuropsychological functions in AD patients.

A review of electroencephalographic changes in diabetes mellitus in relation to major depressive disorder

A bidirectional relationship exists between diabetes mellitus (DM) and major depressive disorder (MDD), with depression commonly reported in both type 1 DM (T1DM) and type 2 DM (T2DM), and depressive symptoms associated with a higher incidence of diabetes. However, how the two conditions are pathologically connected is not completely understood. Similar neurophysiological abnormalities have been reported in both DM and MDD, including elevated electroencephalographic (EEG) activity in low-frequency slow waves and increased latency and/or reduced amplitude of event-related potentials. It is possible that this association reflects some common underlying pathology, and it has been proposed that diabetes may place patients at risk for depression through a biological mechanism linking the metabolic changes of DM to changes in the central nervous system. In this review we will discuss EEG abnormalities in DM, as well as the biological mechanisms underlying various EEG parameters, in order to evaluate whether or not a common EEG biosignature exists between DM and MDD. Identifying such commonalities could significantly inform the current understanding of the mechanisms that subserve the development of the two conditions. Moreover, this new insight may provide the basis for informing new drug discovery capable of mitigating and possibly even preventing both conditions.

Relationship between early and late stages of information processing: an event-related potential study

The brain is capable of elaborating and executing different stages of information processing. However, exactly how these stages are processed in the brain remains largely unknown. This study aimed to analyze the possible correlation between early and late stages of information processing by assessing the latency to, and amplitude of, early and late event-related potential (ERP) components, including P200, N200, premotor potential (PMP) and P300, in healthy participants in the context of a visual oddball paradigm. We found a moderate positive correlation among the latency of P200 (electrode O2), N200 (electrode O2), PMP (electrode C3), P300 (electrode PZ) and the reaction time (RT). In addition, moderate negative correlation between the amplitude of P200 and the latencies of N200 (electrode O2), PMP (electrode C3), P300 (electrode PZ) was found. Therefore, we propose that if the secondary processing of visual input (P200 latency) occurs faster, the following will also happen sooner: discrimination and classification process of this input (N200 latency), motor response processing (PMP latency), reorganization of attention and working memory update (P300 latency), and RT. N200, PMP, and P300 latencies are also anticipated when higher activation level of occipital areas involved in the secondary processing of visual input rise (P200 amplitude).

The impact of depression heterogeneity on inhibitory control

OBJECTIVE

Major depressive disorder (MDD) is associated with deficits in executive cognitive function, including inhibitory control. However, inconsistencies have been found across studies. Depression is a heterogeneous disorder and these inconsistencies may therefore relate to heterogeneity in relatively small samples.

METHOD

Here we sought to examine event-related potentials (ERPs) during a cognitive Go/No-Go task in melancholic (n = 60) and non-melancholic depressed patients (n = 54) relative to controls (n = 114).

RESULTS

Behavioural responses indicate that inhibitory control processes are differentially affected by subtypes of depression such that melancholic patients exhibit a greater number of commission errors and more variable response rates in comparison to non-melancholic patients and controls respectively. However, ERPs do not differ during a cognitive Go/No-Go task when ERPs associated with correct responses are examined.

CONCLUSIONS

These findings indicate that while patients with melancholia differ from patients without melancholia and controls, no neurophysiological differences are observed when controlling for observable behavioural impairment.

Thalamocortical changes in major depression probed by deconvolution and physiology-based modeling

Auditory event-related potentials (ERPs) have been extensively studied in patients with depression, but most studies have focused on purely phenomenological analysis methods, such as component scoring. In contrast, this study applies two recently developed physiology-based methods-fitting using a thalamocortical model of neuronal activity and waveform deconvolution - to data from a selective-attention task in four subject groups (49 patients with melancholic depression, 34 patients with non-melancholic depression, 111 participants with subclinical depressed mood, and 98 healthy controls), to yield insight into physiological differences in attentional processing between participants with major depression and controls. This approach found evidence that: participants with depressed mood, regardless of clinical status, shift from excitation in the thalamocortical system towards inhibition; that clinically depressed participants have decreased relative response amplitude between target and standard waveforms; and that patients with melancholic depression also have increased thalamocortical delays. These findings suggest possible physiological mechanisms underlying different depression subtypes, and may eventually prove useful in motivating new physiology-based diagnostic methods.

Time course of affective processing bias in major depression: An ERP study

The current study investigated the time course of the affective processing bias in major depressive disorder (MDD) in a visual three-stimulus semantic oddball task using event-related potentials (ERPs). MDD patients showed decreased P1 latency over right posterior regions to negative relative to positive target stimuli, reflecting a very early onset of the negativity bias in emotional perception. Compared to controls, MDD patients showed enlarged anterior P2 amplitude to positive target stimuli, reflecting an affective bias in the early attentional stages of processing. In addition, MDD patients showed relatively high N2 and reduced P3 amplitudes to negative compared with positive target stimuli, as well as marginally reduced N2 amplitude to positive target stimuli compared with controls. This suggests that the negativity bias also occurs during later strategic evaluation stages. Therefore, the present study extended previous findings by demonstrating that the affective processing bias in MDD begins in the early stages of perceptual processing and continues at later cognitive stages.

Impact of depression heterogeneity on attention: an auditory oddball event related potential study

BACKGROUND

Major depressive disorder is associated with a reduced ability to attend and concentrate, however, the extent to which attentional impairment is dependent on subtype remains to be clarified.

METHODS

Event-related potentials (ERPs) associated with a well-validated auditory oddball, selective attention task, were recorded to determine the impact of melancholia (n=57) versus non-melancholia (n=48) relative to controls (n=116).

RESULTS

The key findings were an exaggeration of the P200 to both non-target and target stimuli and a reduction in the P300 to targets in patients with melancholia, relative to patients with non-melancholia and controls. In addition, the N200/P300 complex was slowed in latency corresponding to the slowed behavioural responses to targets in melancholia. Stepwise regression analysis also revealed that depression severity, but not psychomotor slowing, contributed to increases in P200 amplitude.

LIMITATIONS

This study is cross-sectional and cannot determine whether the observed ERP changes are a state or trait marker, highlighting the need for a longitudinal study of ERP characteristics in different subgroups of depressed patients.

CONCLUSIONS

Results point to a difficulty in differentiating significant stimuli in the environment in the depressed individual. The combined disruption of early sensory processing (P200) and subsequent context processing (N200/P300 complex) may provide a potential mechanism for the attentional impairment that is frequently observed in depression, particularly in more severe depression.

Inhibition dysfunction in depression: event-related potentials during negative affective priming

The study aimed to investigate whether depressed patients show impairment of valence-dependent inhibition and its neurophysiological correlates. Event-related potentials (ERPs) were collected from 18 patients with unipolar depression and 18 normal controls during an affective negative priming task. A less effective inhibition in patients was specific for negative information. These behavioral effects were paralleled by ERP differences. In addition to the overall reduced P2 amplitude for negative trials and the overall reduced late positive component (LPC) amplitude for positive and negative trials in patients, ERP differences in different conditions for each group were also found. The patients showed reduced central-parietal P2 amplitude and shorter LPC latency in response to negative experimental targets, whereas the controls showed larger left central P2 amplitude and delayed LPC latency in response to negative experimental targets. No such effects were found for positive targets. These results suggest that the inhibition dysfunction of negative affect influences the earlier attention allocation stage and the later evaluation stage in depressed patients.