Differences in the EEG profiles of early and late responders to antipsychotic treatment in first-episode, drug-naive psychotic patients

Macroscale EEG characteristics in antipsychotic-naïve patients with first-episode psychosis and healthy controls

Electroencephalography in patients with a first episode of psychosis (FEP) may contribute to the diagnosis and treatment response prediction. Findings in the literature vary due to small sample sizes, medication effects, and variable illness duration. We studied macroscale resting-state EEG characteristics of antipsychotic naïve patients with FEP. We tested (1) for differences between FEP patients and controls, (2) if EEG could be used to classify patients as FEP, and (3) if EEG could be used to predict treatment response to antipsychotic medication. In total, we studied EEG recordings of 62 antipsychotic-naïve patients with FEP and 106 healthy controls. Spectral power, phase-based and amplitude-based functional connectivity, and macroscale network characteristics were analyzed, resulting in 60 EEG variables across four frequency bands. Positive and Negative Symptom Scale (PANSS) were assessed at baseline and 4-6 weeks follow-up after treatment with amisulpride or aripiprazole. Mann-Whitney U tests, a random forest (RF) classifier and RF regression were used for statistical analysis. Our study found that at baseline, FEP patients did not differ from controls in any of the EEG characteristics. A random forest classifier showed chance-level discrimination between patients and controls. The random forest regression explained 23% variance in positive symptom reduction after treatment in the patient group. In conclusion, in this largest antipsychotic- naïve EEG sample to date in FEP patients, we found no differences in macroscale EEG characteristics between patients with FEP and healthy controls. However, these EEG characteristics did show predictive value for positive symptom reduction following treatment with antipsychotic medication.

Effects of Ketamine on Resting-State EEG Activity and Their Relationship to Perceptual/Dissociative Symptoms in Healthy Humans

N-methyl-D-aspartate (NMDA) receptor antagonists administered to healthy humans results in schizophrenia-like symptoms, which preclinical research suggests are due to glutamatergically altered brain oscillations. Here, we examined resting-state electroencephalographic activity in 21 healthy volunteers assessed in a placebo-controlled, double-blind, randomized study involving administration of either a saline infusion or a sub-anesthetic dose of ketamine, an NMDA receptor antagonist. Frequency-specific current source density (CSD) was assessed at sensor-level and source-level using eLORETA within regions of interest of a triple network model of schizophrenia (this model posits a dysfunctional switching between large-scale Default Mode and Central Executive networks by the monitor-controlling Salience Network). These CSDs were measured in each session along with subjective symptoms as indexed with the Clinician Administered Dissociative States Scale. Ketamine-induced CSD reductions in slow (delta/theta and alpha) and increases in fast (gamma) frequencies at scalp electrode sites were paralleled by frequency-specific CSD changes in the Default Mode, Central Executive, and Salience networks. Subjective symptoms scores were increased with ketamine and ratings of depersonalization in particular were associated with alpha CSD reductions in general and in specific regions of interest in each of the three networks. These results tentatively support the hypothesis that pathological brain oscillations associated with hypofunctional NMDA receptor activity may contribute to the emergence of the perceptual/dissociate symptoms of schizophrenia.

Electroencephalographic abnormalities and 5-year outcome in first-episode psychosis

OBJECTIVE

To examine the relation of electroencephalographic abnormalities to 5-year outcomes in first-episode psychosis (FEP).

METHODS

Patients (n = 103) had their baseline electroencephalogram (EEG) classified by modified Mayo Clinic criteria. Symptoms and psychosocial functioning were rated after 5 years of treatment.

RESULTS

Dysrhythmic EEG was associated with persistence in positive and negative symptoms of psychoses and poorer psychosocial functioning at 5-year follow-up, independently of other characteristics, such as duration of untreated illness or premorbid adjustment. A higher percentage of people with comorbid substance use disorder had normal EEG.

CONCLUSIONS

Abnormal baseline EEG in FEP is associated with poorer 5-year symptomatic and functional outcome.

Comodulation of dopamine and serotonin on prefrontal cortical rhythms: a theoretical study

The prefrontal cortex (PFC) is implicated to play an important role in cognitive control. Abnormal PFC activities and rhythms have been observed in some neurological and neuropsychiatric disorders, and evidences suggest influences from the neuromodulators dopamine (DA) and serotonin (5-HT). Despite the high level of interest in these brain systems, the combined effects of DA and 5-HT modulation on PFC dynamics remain unknown. In this work, we build a mathematical model that incorporates available experimental findings to systematically study the comodulation of DA and 5-HT on the network behavior, focusing on beta and gamma band oscillations. Single neuronal model shows pyramidal cells with 5-HT1A and 2A receptors can be non-monotonically modulated by 5-HT. Two-population excitatory-inhibitory type network consisting of pyramidal cells with D1 receptors can provide rich repertoires of oscillatory behavior. In particular, 5-HT and DA can modulate the amplitude and frequency of the oscillations, which can emerge or cease, depending on receptor types. Certain receptor combinations are conducive for the robustness of the oscillatory regime, or the existence of multiple discrete oscillatory regimes. In a multi-population heterogeneous model that takes into account possible combination of receptors, we demonstrate that robust network oscillations require high DA concentration. We also show that selective D1 receptor antagonists (agonists) tend to suppress (enhance) network oscillations, increase the frequency from beta toward gamma band, while selective 5-HT1A antagonists (agonists) act in opposite ways. Selective D2 or 5-HT2A receptor antagonists (agonists) can lead to decrease (increase) in oscillation amplitude, but only 5-HT2A antagonists (agonists) can increase (decrease) the frequency. These results are comparable to some pharmacological effects. Our work illustrates the complex mechanisms of DA and 5-HT when operating simultaneously through multiple receptors.

Treatment Response in First-episode Schizophrenia

First episode schizophrenia (FES) patients tend to be more responsive to treatment. An adequate response has been associated with a favourable long-term course in FES patients. Yet, despite the generally very favourable response profile around one quarter of the patients shows persisting symptoms of psychosis. To improve the outcome and course of psychosis great effort has emerged in identifying biological and clinical variables associated with non-response in order to identify non-responders as early as possible and adopt specific treatment strategies improving illness outcome. Different antipsychotic treatment regimens have been evaluated in terms of their efficacy in reducing symptoms of FES with psychological interventions gaining increasing importance in the treatment concept of patients suffering from their first illness episode. Therefore, aim of this review is to summarize current evidence on the response patterns, the most important predictors of response/non-response as well as on effective treatment interventions in FES patients.

Time to treatment response in first-episode schizophrenia: should acute treatment trials last several months?

OBJECTIVE

Response patterns may differ between patients with first-episode and multiepisode schizophrenia. This analysis explored trial duration with first-episode patients and asked whether early limited improvement predicts ultimate lack of treatment response with first-episode patients as it does with multiepisode patients.

METHOD

One hundred twelve subjects (mean age = 23.3 years, SD = 5.1 years) who presented between November 1998 and October 2004 with a first episode of psychosis and had a DSM-IV diagnosis of schizophrenia or schizophreniform or schizoaffective disorder were randomly assigned to treatment with olanzapine or risperidone for 16 weeks. Treatment response, the primary outcome measure, was defined as a rating of mild or better on all of the positive symptom items on the Schedule for Affective Disorders and Schizophrenia Change Version With Psychosis and Disorganization Items. Response rates were calculated for each study week. A logistic regression analysis examined the association between percentage reduction in symptom severity scores from baseline values at weeks 2, 4, or 8 and response by week 16. The study was conducted at The Zucker Hillside Hospital, Glen Oaks, New York and the Bronx-Lebanon Hospital Center, Bronx, New York.

RESULTS

The estimated cumulative response rate was 39.59% (95% CI, 29.77%-49.41%) by week 8 and 65.19% (95% CI, 55.11%-75.27%) by week 16. The confidence intervals for estimated response at weeks 10, 12, 14, and 16 were not distinct. Response rates increased approximately 5 to 6 percentage points each 2-week interval between week 10 and 16. Percentage reduction in symptom severity score at week 4 (but not 2 or 8) was associated (χ²₁ = 3.96; P < .05) with responder status at week 16 (odds ratio = 1.03; 95% CI, 1.00-1.05). However, receiver operating characteristic curves did not suggest any level of percentage symptom reduction that would be clinically useful as a predictor of response by week 16.

CONCLUSIONS

Many first-episode patients respond between weeks 8 and 16 of treatment with a single antipsychotic medication. Limited early symptom improvement does not identify those first-episode patients who will not improve with a full 16-week trial with enough accuracy to be clinically useful.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00000374.

EEG: a helpful tool in the prediction of psychosis

OBJECTIVE

EEG investigation in patients with an at risk mental state (ARMS) for psychosis and patients with a first episode of psychosis (FE) in comparison to healthy controls (HC) in a clinical follow up study of Early Detection of Psychosis.

METHOD

Seventy-three patients (42 ARMS, 31 FE) and 35 HC were investigated. ARMS patients were followed up in order to monitor transition to psychosis. Psychopathology was assessed with respect to positive and negative symptoms. At study baseline EEG was recorded using the 10/20 system. Two blinded neurologists analyzed the EEGs visually for presence of generalized or focal slowing and epileptiform discharges. EEG data were controlled for medication and substance abuse. For statistical analyses we used chi(2)-tests, logistic regression, ANOVA, and receiver operating characteristics.

RESULTS

Patients showed significantly more pathological EEG abnormalities than HC (P < 0.05), located more frequently in temporal or fronto-temporal regions (P < 0.01) of the brain, with twice as many pathologies in ARMS than in FE patients. The specificity of the prediction of psychosis could be increased from 59 to 73% by considering EEG pathology in addition to psychopathology alone. In contrast, sensitivity of prediction remained unchanged.

CONCLUSIONS

These results show that EEG investigation in patients at risk for psychosis can add to the identification of those patients who will not develop psychosis later on.

REM sleep EEG spectral analysis in patients with first-episode schizophrenia

The pathophysiology of schizophrenia includes abnormalities in subcortical-cortical transfer of information that can be studied using REM sleep EEG spectral analysis, a measure that reflects spontaneous and endogenous thalamocortical activity. We recorded 10 patients with first-episode schizophrenia and 30 healthy controls for two consecutive nights in a sleep laboratory, using a 10-electrode EEG montage. Sixty seconds of REM sleep EEG without artifact were analyzed using FFT spectral analysis. Absolute and relative spectral amplitudes of five frequency bands (delta, theta, alpha, beta1 and beta2) were extracted and compared between the two groups. Frequency bands with significant differences were correlated with BPRS positive and negative symptoms scores. Patients with schizophrenia showed lower relative alpha and higher relative beta2 spectral amplitudes compared to healthy controls over the averaged total scalp. Analysis using cortical regions showed lower relative alpha over frontal, central and temporal regions and higher relative beta2 over the occipital region. Absolute spectral amplitude was not different between groups for any given EEG band. However, absolute alpha activity correlated negatively with BPRS positive symptoms scores and correlated positively with negative symptoms scores. Since similar results have been reported following EEG spectral analysis during the waking state, we conclude that abnormalities of subcortical-cortical transfer of information in schizophrenia could be generated by mechanisms common to REM sleep and waking.

EEG abnormalities and 3-year outcome in first episode psychosis

OBJECTIVE

This study assesses the relationship of EEG to several aspects of 3 year symptomatic and functional outcome in first episode psychosis.

METHOD

A total of 117 patients with first episode psychosis had their baseline EEG classified by modified Mayo Clinic criteria as normal, essentially normal or dysrhythmia. Socio-demographic variables, duration of illness and of untreated psychosis and premorbid adjustment were also recorded. Positive and negative symptoms of psychoses, depression, anxiety and global functioning were rated on entry and after 3 years of treatment.

RESULTS

Patients with a dysrhythmic EEG at entry into treatment showed significantly greater persistence in both positive and negative symptoms of psychoses as well as anxiety and depression over 3 years. These findings were independent of duration of untreated illness or premorbid adjustment.

CONCLUSION

An abnormal baseline EEG in patients with first episode psychosis is associated with a poorer symptomatic outcome at 3-year follow-up.

EEG abnormalities and two year outcome in first episode psychosis

OBJECTIVE

This study examines the relationship of EEG to 2 year symptomatic outcome, duration of illness and untreated psychosis and gender.

METHOD

A total of 122 patients presenting for treatment of first episode psychosis had their baseline EEG classified by modified Mayo Clinic system criteria as normal, essentially normal or dysrhythmia. Positive and negative symptoms of psychoses were rated on entry and after 2 years of treatment. The socio-demographic variables and duration of illness and of untreated psychosis were also recorded.

RESULTS

Patients with a normal EEG showed significantly more reduction in both positive and negative symptoms of psychoses over 2 years and were more likely to be in 'remission' as compared with the essentially normal or dysrhythmia group. The dysrhythmic group had significantly higher duration of illness than either the normal or essentially normal groups. There were no gender differences in the distribution of EEGs.

CONCLUSION

An abnormal EEG in patients with first episode psychosis is associated with a poorer prognosis and a longer duration of untreated illness.

Nongenetic pathologic developments of brain-wave patterns in monozygotic twins discordant and concordant for schizophrenia

Evidence from previous studies has suggested that the inter-individual differences in human brain-wave patterns (EEG) are predominantly determined by genetic factors. In particular, the within-pair EEG concordance of monozygotic (mz) twins was found to be typically as high as r = 0.81 across channels and frequency bands, thus being comparable to that between repeated assessments on the same individual with typically r = 0.83. Yet our investigations into mz twins discordant and concordant for schizophrenia yielded a significantly reduced within-pair EEG concordance for both, the pairs discordant for schizophrenia and the pairs concordant for schizophrenia (with concordance for schizophrenia assessed through a syndrome-oriented approach). A multivariate discriminant function of EEG parameters distinguished in a reproducible way between affected and unaffected subjects at an overall performance of >75% correctly classified subjects, while the severity of illness, as derived from EEG-differences between affected and unaffected subjects, was closely related to the severity of illness as provided by psychopathology syndrome scores. Consequently, EEG anomalies associated with schizophrenia and manifested differently in the mz co-twins concordant for schizophrenia are likely the effect of nongenetic, pathologic processes that evolved independently in the co-twins' genetically identical brains once the illness began to progress. The existence of such nongenetic processes would suggest a modification of the standard phenotype-to-genotype search strategies of molecular-genetic studies that aim to link the schizophrenia phenotype to genetic vulnerability factors.

EEG abnormalities and outcome in first-episode psychosis

OBJECTIVE

There is widespread consensus that the EEG is not useful for the detection of clinically relevant abnormalities in patients with psychosis. Given that the EEG records brain dysfunction, this study examines whether an abnormal EEG in first-episode psychosis patients is associated with poorer prognosis, compared with a normal EEG.

METHOD

At their initial assessment, 61 patients with first-episode psychosis had an EEG classified according to the following modified Mayo Clinic system: normal, essentially normal (that is, one or more elements of questionable normality), or dysrhythmia (grade I to V). We assessed psychiatric symptoms using the Scale for Assessment of Negative Symptoms (SANS) and the Scale for Assessment of Positive Symptoms (SAPS) on entry and after 1 year of treatment. Psychosis is considered to have remitted if there are no, or minimal, psychotic symptoms (that is, a rating of 2 or less on every SAPS global rating), maintained for 1 month.

RESULTS

At the end of 1 year, 19/21 (90.5%) patients with a normal EEG had a remission of their positive symptoms, compared with 18/28 (64.3%) of those with an essentially normal EEG and only 7/12 (58.3%) of those with dysrhythmia. Negative symptoms were reduced by more than 50% in 11/18 (61.1%) patients with a normal EEG, compared with 10/28 (35.7%) patients with an essentially normal EEG. None of the 8 patients with dysrhythmia on their EEG experienced reduced negative symptoms.

CONCLUSION

The above findings suggest that an abnormal EEG in patients with first-episode psychosis is associated with a poorer prognosis.

Negative symptom resolution and improvements in specific cognitive deficits after acute treatment in first-episode schizophrenia

Patients with first-episode schizophrenia show significant cognitive impairments even at this early phase of their illness. Antipsychotic medication improves clinical symptomatology, but the effectiveness of this treatment on neuropsychological deficits remains unclear. We investigated clinical symptom and neuropsychological performance change in 34 unmedicated first-episode psychotic patients (17 males, 17 females) from the time prior to treatment until 33.6+/-11.3 days after treatment initiation at which time patients demonstrated meaningful recovery from psychosis. Twenty-four matched healthy subjects were also studied. Performance in most neuropsychological functions (language skills, attention, nonverbal learning and reasoning, motor speed) remained stable for the group as a whole. However, reduction in negative symptoms was significantly correlated with performance increases in verbal fluency and attention. Higher negative symptom recovery was associated with improvement of cognitive performance to levels approaching those of healthy subjects, whereas low or no negative symptom improvement was associated with stable or decreased cognitive performance. Reduction in positive symptoms was not associated with change in cognitive abilities. These findings suggest a linkage between early, treatment-induced improvements in negative symptoms and reductions in distinct cognitive deficits.

Electrophysiology in neuropsychiatric research: a network perspective

A growing number of anatomic and physiologic studies have shown that parallel sensory and motor information processing occurs in multiple cortical areas. These findings challenge the traditional model of brain processing, which states that the brain is a collection of physically discrete processing modules that pass information to each other by neuronal impulses in a stepwise manner. New concepts based on neural network models suggest that the brain is a dynamically shifting collection of interpenetrating, distributed, and transient neural networks. Neither of these models is necessarily mutually exclusive, but each gives different perspectives on the brain that might be complementary. Each model has its own research methodology, with functional magnetic resonance imaging supporting notions of modular processing, and electrophysiology (eg, electroencephalography) emphasizing the network model. These two technologies might be combined fruitfully in the near future to provide us with a better understanding of the brain. However, this common enterprise can succeed only when the inherent limitations and advantages of both models and technologies are known. After a general introduction about electrophysiology as a research tool and its relation to the network model, several practical examples are given on the generation of pathophysiologic models and disease classification, intermediate phenotyping for genetic investigations, and pharmacodynamic modeling. Finally, proposals are made about how to integrate electrophysiology and neuroimaging methods.