Auditory event-related potentials in panic disorder

Robust single-trial event-related potentials differentiate between distress and fear disorders

Recent evidence indicates that measures of brain functioning as indexed by event-related potentials (ERPs) on the electroencephalogram align more closely to transdiagnostic measures of psychopathology than to categorical taxonomies. The Hierarchical Taxonomy of Psychopathology (HiTOP) is a transdiagnostic, dimensional framework aiming to solve issues of comorbidity, symptom heterogeneity, and arbitrary diagnostic boundaries. Based on shared features, the emotional disorders are allocated into subfactors Distress and Fear. Evidence indicates that disorders that are close in the HiTOP hierarchy share etiology, symptom profiles, and treatment outcomes. However, further studies testing the biological underpinnings of the HiTOP are called for. In this study, we assessed differences between Distress and Fear in a range of well-studied ERP components. In total, 50 patients with emotional disorders were divided into two groups (Distress, N = 25; Fear, N = 25) according to HiTOP criteria and compared against 37 healthy comparison (HC) subjects. Addressing issues in traditional ERP preprocessing and analysis methods, we applied robust single-trial analysis as implemented in the EEGLAB toolbox LIMO EEG. Several ERP components were found to differ between the groups. Surprisingly, we found no difference between Fear and HC for any of the ERPs. This suggests that some well-established results from the literature, e.g., increased error-related negativity in OCD, are not a shared neurobiological correlate of the Fear subfactor. Conversely, for Distress, we found reductions compared to Fear and HC in several ERP components across paradigms. Future studies could utilize HiTOP-validated psychopathology measures to more precisely define subfactor groups.

P50, N100, and P200 Sensory Gating in Panic Disorder

Panic disorder (PD) has been linked to abnormalities in information processing. However, only little evidence has been published for sensory gating in PD. Sensory gating describes the brain's ability to exclude stimuli of low relevance from higher level information processing, thereby sustaining efficient cognitive processing. Deficits in sensory gating have been associated with various psychiatric conditions, most prominently schizophrenia. In this case-control event-related potential study, we tested 32 patients with PD and 39 healthy controls in a double click paradigm. Both groups were compared with regard to pre-attentive (P50), early-attentive (N100), and late-attentive (P200) sensory gating indices. Contrary to a hypothesized deficit, PD patients and healthy controls showed no differences in P50, N100 and P200 values. These results suggest that sensory gating seems to be functional across the pre-attentive, early-attentive, and late-attentive time span in this clinical population. Given this consistency across auditory sensory gating indices, further research aiming to clarify information processing deficits in PD should focus on other neurophysiological markers to investigate information processing deficits in PD (eg, P300, error-related negativity or mismatch negativity).

Abnormal frontal generator during auditory sensory gating in panic disorder: An MEG study

Patients with panic disorder (PD) exhibit abnormalities in early-stage information processing, even for the nonthreatening stimuli. A previous event-related potential study reported that PD patients show a deficit in sensory gating (SG), a protective mechanism of the brain to filter out irrelevant sensory inputs. However, there is no clear understanding about the neural correlates of SG deficits in PD. Moreover, whether SG deficits, if any, are associated with clinical manifestations remain unknown. In this study, 18 patients with PD and 20 age- and gender-matched healthy controls were recruited to perform auditory paired-stimulus paradigm using magnetoencephalographic (MEG) recordings. Results showed that PD patients demonstrated significantly higher M50 SG ratios in the right inferior frontal gyrus (RIFG) and higher M100 SG ratios in both RIFG and right superior temporal gyrus (RSTG) than those of the control group. It was important to note that in the RIFG, the M50 SG ratios correlated significantly with the scores of Body Sensation Questionnaire (BSQ) and Distractibility scale of Sensory Gating Inventory among patients with PD. In conclusion, this study suggests that PD patients exhibited a deficient ability to filter out irrelevant information, and such a defect might lead to cognitive misinterpretation of somatic sensations and distractibility.

Reduced Sensitivity to Non-Fear-Related Stimulus Changes in Panic Disorder

Panic disorder (PD) is associated with increased body vigilance and reduced cognitive resources directed at non-fear-related stimuli, particularly in the absence of stimulus-rich environments. To date, only few studies have investigated whether this deficit in PD is reflected in reduced mismatch negativity (MMN), an event-related potential indexing preattentive sensitivity to unexpected stimulus changes. We tested 35 patients affected by PD and 42 matched healthy controls in an oddball paradigm, using frequency and duration deviant stimuli to measure auditory MMN. PD patients displayed reduced duration MMN amplitudes in comparison to healthy controls. No group differences were detected for duration MMN latency, as well as frequency MMN indices. Results support the notion of reduced processing of non-fear-related stimuli in PD patients, particularly with regard to the preattentive processing of sound duration deviants. Additionally, our findings are in line with clinical studies reporting divergent deficits in preattentive processing of frequency and duration deviants.

AUDITORY EVOKED POTENTIALS EVIDENCE FOR DIFFERENCES IN INFORMATION PROCESSING BETWEEN HIGH AND LOW HYPNOTIZABLE SUBJECTS

N100 and P300 auditory evoked potentials in 2-stimulus oddball paradigm were analyzed in high (HH, n = 18) and low (LH, n = 15) hypnotizable participants under waking condition. LH subjects committed more errors than HH subjects. HH subjects demonstrated shorter N100 latencies at frontal electrodes and significant N100 differences between target and nontarget stimuli (higher N100 amplitude and increased latency at parietal sites to targets vs. nontargets), whereas LH subjects failed to show any differences. The overall increase of P300 amplitude with frontal-central localization of P300 maximum was found in HH subjects compared to LH subjects. The obtained results support the psychophysiological model of HH individuals having more effective frontal attentional systems involved in detecting, integrating, and filtering relevant information.

Mismatch negativity indices of enhanced preattentive automatic processing in panic disorder as measured by a multi-feature paradigm

Panic disorder (PD) is a mental disorder characterized by recurrent panic attacks and worrying about having subsequent attacks. Mismatch negativity (MMN) has been established as a correlate of preattentive automatic processing. The aim of the present study is to investigate the preattentive automatic information processing in PD patients as measured by MMN. Subjects included 15 medication-free patients with a DSM-IV diagnosis of PD and 15 age-matched healthy volunteers. MMN was investigated using event-related potentials. The protocol used a multi-feature paradigm. Mean amplitudes and peak latencies were subjected to repeated-measures ANOVAs. PD patients showed a significantly increased MMN of sound intensity and location compared with healthy participants. The correlation between the amplitudes of intensity-MMN and disease severity was also significant. These data provide evidence of anomalous preattentive automatic information processing in PD patients. In particular, the abnormality may be specific for PD.

Electroencephalographic findings in panic disorder

Some studies have reported the importance of electroencephalography (EEG) as a method for investigating abnormal parameters in psychiatric disorders. Different findings in time and frequency domain analysis with regard to central nervous system arousal during acute panic states have already been obtained. This study aimed to systematically review the EEG findings in panic disorder (PD), discuss them having a currently accepted neuroanatomical hypothesis for this pathology as a basis, and identify limitations in the selected studies. Literature search was conducted in the databases PubMed and ISI Web of Knowledge, using the keywords electroencephalography and panic disorder; 16 articles were selected. Despite the inconsistency of EEG findings in PD, the major conclusions about the absolute power of alpha and beta bands point to a decreased alpha power, while beta power tends to increase. Different asymmetry patterns were found between studies. Coherence studies pointed to a lower degree of inter-hemispheric functional connectivity at the frontal region and intra-hemispheric at the bilateral temporal region. Studies on possible related events showed changes in memory processing in PD patients when exposed to aversive stimuli. It was noticed that most findings reflect the current neurobiological hypothesis of PD, where inhibitory deficits of the prefrontal cortex related to the modulation of amygdala activity, and the subsequent activation of subcortical regions, may be responsible to trigger anxiety responses. We approached some important issues that need to be considered in further researches, especially the use of different methods for analyzing EEG signals.

Childhood predictors of states of anxiety

Development of the characteristics of social phobia often requires a diathesis in the form of a temperamental bias. A behavioral profile marked by vigorous motor activity and crying to unfamiliar stimuli at 4 months of age - called high reactivity- is characteristic of about 20% of healthy, Caucasian infants. This pattern predicts shy behavior in preschool children and symptoms of social anxiety at age 7, and, at age 11, a subdued personality and biological features that are consonant with a hypothesis of amygdalar excitability. The biological variables that best characterize the children who had been high-reactive infants are right-hemisphere activity in the electroencephalogram (EEC), a larger evoked potential from the inferior colliculus, higher sympathetic tone in the cardiovascular system, and larger event-related potentials to discrepant stimuli. About a quarter of 11-year-olds who had been high reactives displayed behavioral and biological characteristics that are in theoretical accord with the hypothesis of amygdalar excitability, while only 1 of 20 displayed a profile characterized by features in opposition to their temperament. The evidence points to a modest temperamental contribution to the development of symptoms currently regarded as diagnostic of social phobia.

Clarifying relations between dispositional aggression and brain potential response: overlapping and distinct contributions of impulsivity and stress reactivity

Impulsive-aggressive individuals exhibit deficits in amplitude of the P3 brain potential response, however, it remains unclear how separable dispositional traits account for this association. The current study sought to clarify the basis of this association by examining contributions of trait impulsiveness and stress reactivity to the observed relationship between dispositional aggression and amplitude of the P3 brain potential response in a visual novelty-oddball procedure. A significant negative association was found between aggressiveness and amplitude of P3 response to both target and novel stimuli over frontal-central scalp sites. Impulsivity showed a parallel inverse relationship with P3 amplitude, attributable to its overlap with dispositional aggression. In contrast, stress reactivity did not exhibit a zero-order association with P3 amplitude, but modestly predicted P3 in a positive direction after accounting for its overlap with aggression. Results are discussed in terms of their implications for individual difference variables and brain processes underlying impulsive-aggressive behavior.

Relationships between auditory event-related potentials and mood state, medication, and comorbid psychiatric illness in patients with bipolar disorder

BACKGROUND

Patients with bipolar disorder (BD) exhibit aberrations in auditory event-related potentials (ERPs), although the relationships between these measures and mood state at testing, comorbid psychiatric illness, presence of psychotic features, and medication usage are unclear. The purpose of this study was to investigate the relationships between these factors and auditory ERP measures in BD patients.

METHODS

An auditory 'oddball' discrimination task was used to elicit ERPs from 69 patients with type I BD and 52 healthy controls. Patients were placed into subgroups based upon their mood state at testing (euthymic or symptomatic), and ANOVA was used to compare amplitude and peak latency measures from the N100, P200, N200, and P300 ERP components across subgroups. Multiple regression was used to investigate relationships between ERP measures and comorbid psychiatric diagnosis, history of psychotic features, and medication status.

RESULTS

Relative to healthy control participants, euthymic and symptomatic BD patients exhibited reduced P300 and P200 amplitude, but ERP measures did not differ among BD patients on the basis of mood status. A history of a comorbid anxiety disorder was associated with reduced N200 peak latency, but prolonged P300 peak latency among BD patients. No other relationships between clinical variables and ERP measures were significant.

CONCLUSIONS

The results suggest that disrupted auditory attention may be observed in BD patients regardless of their mood state at testing, medication status, or history of psychosis. These results extend previous findings, and provide further evidence for aberrations in the P300 ERP as an endophenotype for BD.

Attention to novelty in behaviorally inhibited adolescents moderates risk for anxiety

BACKGROUND

Individual differences in specific components of attention contribute to behavioral reactivity and regulation. Children with the temperament of behavioral inhibition (BI) provide a good context for considering the manner in which certain components of attention shape behavior. Infants and children characterized as behaviorally inhibited manifest signs of heightened orienting to novelty. The current study considers whether this attention profile moderates risk for clinical anxiety disorders among adolescents with a history of BI.

METHODS

Participants were assessed at multiple time points for BI, beginning in early childhood. At adolescence, event-related potentials (ERPs) were recorded during a three-stimulus auditory novelty oddball task, which employed frequent standard and infrequent deviant tones as well as a set of complex, novel sounds. Clinical diagnosis was carried out using the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version (K-SADS-PL). P3 and mismatch negativity (MMN) components were examined at midline frontal, central, and parietal electrode sites.

RESULTS

Individuals who displayed high levels of BI during childhood and increased P3 amplitude to novelty in adolescence were more likely to have a history of anxiety disorders compared to behaviorally inhibited adolescents with lower P3 amplitudes. Groups did not differ on measures of MMN.

CONCLUSIONS

Increased neural responses to novelty moderate risk for anxiety disorders amongst individuals with a history of BI.

Evidence-based medicine evaluation of electrophysiological studies of the anxiety disorders

We provide a systematic, evidence-based medicine (EBM) review of the field of electrophysiology in the anxiety disorders. Presently, electrophysiological studies of anxiety focus primarily on etiological aspects of brain dysfunction. The review highlights many functional similarities across studies, but also identifies patterns that clearly differentiate disorder classifications. Such measures offer clinical utility as reliable and objective indicators of brain dysfunction in individuals and indicate potential as biomarkers for the improvement of diagnostic specificity and for informing treatment decisions and prognostic assessments. Common to most of the anxiety disorders is basal instability in cortical arousal, as reflected in measures of quantitative electroencephalography (qEEG). Resting electroencephalographic (EEG) measures tend to correlate with symptom sub-patterns and be exacerbated by condition-specific stimulation. Also common to most of the anxiety disorders are condition-specific difficulties with sensory gating and the allocation and deployment of attention. These are clearly evident from evoked potential (EP) and event-related potential (ERP) electrical measures of information processing in obsessive compulsive disorder (OCD), post-traumatic stress disorder (PTSD), panic disorder (PD), generalized anxiety disorder (GAD) and the phobias. Other'ERP measures clearly differentiate the disorders. However, there is considerable variation across studies, with inclusion and exclusion criteria, medication status and control group selection not standardized within condition or across studies. Study numbers generally preclude analysis for confound removal or for the derivation of diagnostic biomarker patterns at this time. The current trend towards development of databases of brain and cognitive function is likely to obviate these difficulties. In particular, electrophysiological measures of function are likely to play a significant role in the development and subsequent adaptations of DSM-V and assist critically in securing improvements in nosological and treatment specificity.

Cognitive functions and the state of nonspecific brain systems in panic disorders

A total of 93 patients with panic disorders and 36 healthy control subjects were studied. Clinical-neurological, psychometric, neuropsychological, and neurophysiological (auditory cognitive evoked potentials) investigations were performed. Patients with typical panic disorders were characterized by increased levels of anxiety and depression, along with impairments to cognitive functions in the form of decreases in short-term memory and attention, as compared with healthy subjects. Patients with atypical panic disorders differed from patients with typical panic disorders in having lower levels of anxiety, more severe depression, and more marked cognitive disorders. As compared with healthy subjects, patients with atypical panic disorders showed reductions in the amplitude of the P300 evoked potential wave, while patients with typical panic disorders showed increases. It is suggested that changes in the amplitude parameters of the P300 wave are associated with dysfunction of the limbic-reticular structures of the brain in patients with panic disorders.

Brain Response to Unexpected Novel Noises in Children with Low and High Trait Anxiety

The behavioral inhibition system [Gray, J. A. The neuropsychology of anxiety: An enquiry into the functions of the septo-hippocampal system. Oxford: Oxford University Press, 1982] proposes that anxiety is associated with the processing of novel stimuli. We aimed to explore this relationship by recording auditory event-related potentials associated with unexpected novel noises in typically developing children. Children aged 10–14 years with low (n = 12) and high (n = 11) self-report trait anxiety were assessed using a novelty oddball task. The N1 associated with novel stimuli, specifically the “N1c” component maximal at temporal lobe sites, was of significantly longer latency (p = .014) and greater amplitude (p = .004) in the high compared with the low anxious group. This group difference was supported by linear correlations between N1c amplitude and trait anxiety scores. There was no effect of anxiety on the later novelty P3. These data suggest a subtle moderating role of trait anxiety on brain response to novelty, and further research with clinically anxious children is indicated.

P50 sensory gating in panic disorder

Previous studies with prepulse inhibition in panic disorder (PD) have suggested that the early stages of sensory information processing are abnormal in patients with PD. To further investigate sensory gating function in panic disorder we performed a case-control study in a sample of 28 patients with PD, compared to 28 normal subjects and 28 schizophrenic subjects evaluating auditory mid-latency evoked potential P50 in a double-click paradigm as a measure of sensory gating. PD subjects showed weaker sensory gating as evidenced by higher P50 ratios as compared to normal subjects (62.5% vs. 45.4%, p=0.03) and higher S2 (test) amplitude (3.5 microV vs. 2.1 microV, p=0.01). Schizophrenic subjects when compared to healthy controls showed higher P50 ratios as compared to normal subjects (79.2% vs. 45.4%, p<0.01) and higher S2 amplitude (3.3 microV vs. 2.1 microV, p=0.01), but were not statistically different from PD subjects (p>0.1). The present study corroborates recent findings of sensory gating dysfunction in PD. Further studies are still necessary to better understand the pathophysiology of this neurophysiological dysfunction and its nature as a trait or a state marker.

Event-related potentials in panic disorder and generalized anxiety disorder

To evaluate the neurophysiological differences between panic disorder (PD) and generalized anxiety disorder (GAD), 52 patients with PD and 34 with GAD were investigated using event-related potentials (ERP). The ERP were recorded using a tone discrimination task, and peak latencies for N1, P2, N2, and P3 at a Pz electrode site were measured. In addition to analyzing the peak latencies of the ERP, the interpeak latencies (IPL; N1-P2, P2-N2, and N2-P3) were also analyzed. The same analysis was performed in 28 age-matched healthy volunteers (controls). When compared to those of the GAD and control groups, the mean latencies of P2, N2, and P3 were shorter in the PD patients. With regard to the IPL in the PD patients, the N1-P2 IPL was shorter than that in the other groups, and no individual with PD had a longer N1-P2 IPL than 1 SD above the mean of the controls. These findings suggest that certain attention-related processes in the cerebrum that affect ERP data are accelerated in PD patients. These findings demonstrate that it may be useful to neurophysiologically distinguish PD from GAD by measuring ERP peak latencies and IPL.

The N200 abnormalities of auditory event-related potentials in patients with panic disorder

Cognitive impairment in patients with panic disorder (PD) has been studied using event-related potentials (ERPs). However, previous studies obtained ERP data only at a few scalp sites, and seldom investigated N200 measurements from the difference waveforms. In the present study, auditory ERPs were recorded at 16 scalp sites during an active discrimination task of oddball paradigm. Fourteen PD patients (8 with agoraphobia; 6 without agoraphobia) were compared with 14 sex- and age-matched control subjects. For the nontarget waveforms, P2 amplitude was reduced in PD patients. For the target waveforms, a topographical difference between female PD patients and female controls was found for N200 amplitude, which attenuated in female PD patients over the parietal area. Two subcomponents of N200, N2a and N2b, were measured from the difference waveforms. A significant group difference was found for N2b amplitude, which reduced in PD patients compared with unaffected control subjects. It is suggested that N2b reduction reflects an abnormally controlled processing of stimulus information in PD.

Acute cholecystokinin effects on event-related potentials in healthy volunteers

This study investigated the effects of a continuous slow infusion of cholecystokinin tetrapeptide (CCK-4), a neuropeptide with panicogenic properties, on brain event-related potentials (ERPs) in healthy adults. Twenty-four volunteers, 15 females and 9 males, were assigned to infusion with either placebo or CCK-4 in a randomized, double-blind, parallel group design. ERPs, elicited within a standard auditory odd-ball paradigm requiring the counting of rare (20%) occurring 'deviant' tones interspersed among more frequent (80%) occurring 'standard' tones, were assessed once before infusion, and at 10 min and 40 min after the onset of infusion. Compared with the placebo, CCK-4 delayed the latencies of N100 and P200 components elicited by 'deviant' stimuli. No significant treatment differences were observed with respect to N200, P300b, mood or adverse symptoms. These preliminary findings suggest that CCK-4 may interfere with information processing relating to the selection of significant stimuli and as such, may be of relevance to mechanisms underlying panic disorder.

Auditory event-related potentials in panic and generalised anxiety disorders

In this study, we aimed to investigate event-related potential (ERP) changes in panic disorder (PD) and generalised anxiety disorder (GAD) and to determine whether two disorders are different from each other in terms of endogenous potentials. A total of 35 outpatients who fully met DSM-III-R criteria for PD (8 males and 27 females) were included in this study as the PD group. The GAD group consisted of 30 subjects (5 males and 25 females) who met DSM-III-R GAD criteria. The control group consisted of 29 healthy age and sex-matched volunteers (5 males and 24 females) having no history of psychiatric or neurological illness. ERPs were recorded by using auditory "odd-ball two-tone discrimination task" method. It was found that there was significant prolongation in P3 latency in the PD group compared to the GAD and control groups. Our study suggests that there are some disturbances in early information processing in patients with PD but not with GAD.

Phobic anxiety changes the function of brain-gut axis in irritable bowel syndrome

OBJECTIVE

Disease severity in the irritable bowel syndrome (IBS) is highly influenced by psychiatric comorbidity. The mechanism of this influence is generally unknown, even if the brain-gut axis seems to be involved. Recent research has indicated that IBS patients have aberrant perception of visceral stimuli in the CNS. We compared IBS patients with and without comorbid phobic anxiety to see if the comorbid disorder influenced brain information processing of auditory stimuli, and looked for possible consequences with respect to visceral sensitivity thresholds and disease severity.

METHODS

Eleven female patients with IBS with comorbid phobic anxiety disorder were compared with 22 age-matched female IBS patients without such comorbidity. The groups were compared with respect to event-related potentials (ERP), auditory-presented words with emotional contents, barostat-assessed visceral sensitivity thresholds, and symptom levels the last week before assessment.

RESULTS

The comorbid group had a significantly enhanced first negative ERP wave (N1) to all stimuli, indicating increased use of brain attentional resources. It also had increased visceral threshold for the sensation of gas, and reduced gas-stool and gas-discomfort tolerances compared with the noncomorbid group. Enhanced N1 amplitude at the frontal electrode and reduced gas-stools tolerance significantly predicted subjective gas complaints, explaining 47% of the symptom variation.

CONCLUSIONS

The study suggests an association between information processing in the frontal brain and visceral sensitivity characteristics in IBS patients, and indicates that subjective disease-related symptomatology is predicted by brain perceptual characteristics. The findings indicate that an interaction between IBS-related and anxiety-related hyperreactivity in the frontal brain may constitute a psychophysiological mechanism for the contribution of psychiatric comorbidity to severity and duration of the irritable bowel syndrome.

[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.