Mismatch negativity-indexed auditory change detection of speech sounds in early and chronic schizophrenia

Mismatch Negativity and Theta Oscillations Evoked by Auditory Deviance in Early Schizophrenia

BACKGROUND

Amplitude reduction of mismatch negativity (MMN), an event-related potential component indexing NMDA receptor-dependent auditory echoic memory and predictive coding, is widely replicated in schizophrenia. Time-frequency analyses of single-trial electroencephalography epochs suggest that theta oscillation abnormalities underlie MMN deficits in schizophrenia. However, this has received less attention in early schizophrenia (ESZ).

METHODS

Patients with ESZ (n = 89), within 5 years of illness onset, and healthy control subjects (n = 105) completed an electroencephalography MMN paradigm (duration-deviant, pitch-deviant, duration + pitch double-deviant). Repeated measures analyses of variance assessed group differences in MMN, theta intertrial phase coherence (ITC), and theta total power from frontocentral electrodes, after normal age adjustment. Group differences were retested after covarying MMN and theta measures.

RESULTS

Relative to healthy control subjects, patients with ESZ showed auditory deviance deficits. Patients with ESZ had MMN deficits for duration-deviants (p = .041), pitch-deviants (ps = .007), and double-deviants (ps < .047). Patients with ESZ had reduced theta ITC for standards (ps < .040) and duration-deviants (ps < .030). Furthermore, patients with ESZ had reduced theta power across deviants at central electrodes (p = .013). MMN group deficits were not fully accounted for by theta ITC and power, and neither were theta ITC group deficits fully accounted for by MMN. Group differences in theta total power were no longer significant after covarying for MMN.

CONCLUSIONS

Patients with ESZ showed reduced MMN and theta total power for all deviant types. Theta ITC showed a relatively specific reduction for duration-deviants. Although MMN and theta ITC were correlated in ESZ, covarying for one did not fully account for deficits in the other, raising the possibility of their sensitivity to dissociable pathophysiological processes.

Working memory and sensory memory in subclinical high schizotypy: An avenue for understanding schizophrenia?

The search for robust, reliable biomarkers of schizophrenia remains a high priority in psychiatry. Biomarkers are valuable because they can reveal the underlying mechanisms of symptoms and monitor treatment progress and may predict future risk of developing schizophrenia. Despite the existence of various promising biomarkers that relate to symptoms across the schizophrenia spectrum, and despite published recommendations encouraging multivariate metrics, they are rarely investigated simultaneously within the same individuals. In those with schizophrenia, the magnitude of purported biomarkers is complicated by comorbid diagnoses, medications and other treatments. Here, we argue three points. First, we reiterate the importance of assessing multiple biomarkers simultaneously. Second, we argue that investigating biomarkers in those with schizophrenia-related traits (schizotypy) in the general population can accelerate progress in understanding the mechanisms of schizophrenia. We focus on biomarkers of sensory and working memory in schizophrenia and their smaller effects in individuals with nonclinical schizotypy. Third, we note irregularities across research domains leading to the current situation in which there is a preponderance of data on auditory sensory memory and visual working memory, but markedly less in visual (iconic) memory and auditory working memory, particularly when focusing on schizotypy where data are either scarce or inconsistent. Together, this review highlights opportunities for researchers without access to clinical populations to address gaps in knowledge. We conclude by highlighting the theory that early sensory memory deficits contribute negatively to working memory and vice versa. This presents a mechanistic perspective where biomarkers may interact with one another and impact schizophrenia-related symptoms.

Early auditory processing dysfunction in schizophrenia: Mechanisms and implications

Schizophrenia is a major mental disorder that affects approximately 1% of the population worldwide. Cognitive deficits are a key feature of the disorder and a primary cause of long-term disability. Over the past decades, significant literature has accumulated demonstrating impairments in early auditory perceptual processes in schizophrenia. In this review, we first describe early auditory dysfunction in schizophrenia from both a behavioral and neurophysiological perspective and examine their interrelationship with both higher order cognitive constructs and social cognitive processes. Then, we provide insights into underlying pathological processes, especially in relationship to glutamatergic and N-methyl-D-aspartate receptor (NMDAR) dysfunction models. Finally, we discuss the utility of early auditory measures as both treatment targets for precision intervention and as translational biomarkers for etiological investigation. Altogether, this review points out the crucial role of early auditory deficits in the pathophysiology of schizophrenia, in addition to major implications for early intervention and auditory-targeted approaches.

Reduced duration mismatch negativity elicited by the multi-feature 'optimal' paradigm in early-phase psychosis

BACKGROUND

MMN and P3a are EEG-derived event related potentials that are thought to be prospective biomarkers for schizophrenia and, potentially, early-phase psychosis (EPP).

METHODS

EPP (n = 12) and healthy control (n = 35) participants listened to a multi-feature optimal paradigm with five deviant types (gap, duration, location, intensity, and frequency).

RESULTS

There was a significant amplitude difference between the EPP and HC group with duration MMN (p =.02). No significant amplitude differences between groups were found for the P3a waveform. There were several correlations for the EPP group with the BNSS, SOFAS, and PANSS-general questionnaires. Length of illness was not associated with MMN or P3a.

CONCLUSIONS

The optimal paradigm is suitable for eliciting multiple deviant types within a short amount of time in both clinical and healthy populations. This study confirms duration MMN deficits within an EPP group and that MMN is related to functional outcomes and positive and negative symptomology.

Mismatch negativity as an early biomarker of cognitive impairment in schizophrenia

Background

Due to its disturbance in schizophrenic patients, mismatch negativity (MMN) generation is believed to be a potential biomarker for recognizing primary impairments in auditory sensory processing during the course of the disease. However, great controversy exists regarding the type and onset of MMN-related impairments, with the deficits to frequency deviants is more debatable. This cross-sectional, case–control study was conducted to assess the cognitive functions among 33 eligible Egyptian schizophrenics (15 early and 18 chronic), and 30 matched healthy controls by assessing their psychometric tests and correlating them to the coexisting frequency deviant MMN responses (using both tone and speech stimuli).

Results

Deficits in frequency MMN and neuropsychological tests were evident among early and chronic schizophrenics compared to their matched control counterparts, and also between early versus chronic schizophrenia in favor of the later. MMN deficits to speech stimuli were more elicited than tone stimuli among schizophrenics. Moreover, significant correlations were identified between MMN parameters and the results of psychiatric cognitive scales.

Conclusions

We demonstrated that frequency-deviant MMN deficits are evident feature among the enrolled Egyptian schizophrenics. The cognitive functions as indexed by MMN seem affected early, with the striking decrease of MMN amplitude and delay of latency point towards the progression of the illness. The normal lateralization of MMN was absent in chronic schizophrenia. These findings could be helpful in using the MMN as an additional objective tool for confirming cognitive impairments among schizophrenics and to differentiate between early- and chronic-schizophrenic patients for medico-legal purposes and clinical implication for medications.

Reduction of phonetic mismatch negativity may depict illness course and predict functional outcomes in schizophrenia

Schizophrenia (SZ) is characterized by a series of cognitive impairments, including automatic processing impairment of basic auditory information, indexed by mismatch negativity (MMN). Existing studies mainly focus on MMN induced by deviant of single acoustic features, and relatively few studies have focused on complex acoustic stimuli, especially speech-induced MMN. Many cognitive impairments in SZ are related to speech function. Thus, the present study aimed to examine the reduction of phonetic MMN in SZ as a potential biomarker and its relationship with illness course and functional outcomes. Electroencephalogram (EEG) signals were recorded from 32 SZ and 32 healthy controls (HC) in a double oddball paradigm, with /da/ as the standard stimulus and /ba/ and /du/ as the deviant stimuli. MMN was computed for vowel and consonant deviants separately. Clinical symptoms were assessed using the Positive and Negative Symptom Rating Scale (PANSS). Illness duration and illness relapse were acquired by combining clinical interviews and electronic medical records. Functional outcomes were assessed using the Global Assessment of Functioning scale (GAF). Compared with HC, SZ showed lower amplitudes of phonetic MMN, especially for vowel deviants. In addition, the MMN amplitude of the vowel deviant was significantly correlated with illness duration, illness relapse, and functional outcomes among patients with SZ. These findings indicate that the pre-attentive automatic phonetic processing of SZ was impaired for both consonants and vowels, while the vowel processing deficit may be the key speech processing deficit in SZ, which could depict the illness course and predict the functional outcomes.

Suicidality: An Evolutionary Concept Analysis

Suicide is a preventable health problem. Multiple definitions and inconsistent use of the term suicidality can result in failure to properly recognize suicide risk and behavior and confuses suicide research. Clarification of the suicidality concept is needed to facilitate the care for individuals at risk for suicide. Using Rodgers' evolutionary concept analysis method, this analysis describes the breadth and scope of the suicidality concept. Findings indicate suicidality covers a spectrum of suicidal risk and levels of emotional suffering and intent. The analysis does not draw definite conclusions, but outlines a direction for further research.

Special Report on the Impact of the COVID-19 Pandemic on Clinical EEG and Research and Consensus Recommendations for the Safe Use of EEG

INTRODUCTION

The global COVID-19 pandemic has affected the economy, daily life, and mental/physical health. The latter includes the use of electroencephalography (EEG) in clinical practice and research. We report a survey of the impact of COVID-19 on the use of clinical EEG in practice and research in several countries, and the recommendations of an international panel of experts for the safe application of EEG during and after this pandemic.

METHODS

Fifteen clinicians from 8 different countries and 25 researchers from 13 different countries reported the impact of COVID-19 on their EEG activities, the procedures implemented in response to the COVID-19 pandemic, and precautions planned or already implemented during the reopening of EEG activities.

RESULTS

Of the 15 clinical centers responding, 11 reported a total stoppage of all EEG activities, while 4 reduced the number of tests per day. In research settings, all 25 laboratories reported a complete stoppage of activity, with 7 laboratories reopening to some extent since initial closure. In both settings, recommended precautions for restarting or continuing EEG recording included strict hygienic rules, social distance, and assessment for infection symptoms among staff and patients/participants.

CONCLUSIONS

The COVID-19 pandemic interfered with the use of EEG recordings in clinical practice and even more in clinical research. We suggest updated best practices to allow safe EEG recordings in both research and clinical settings. The continued use of EEG is important in those with psychiatric diseases, particularly in times of social alarm such as the COVID-19 pandemic.

CDP-choline and galantamine, a personalized α7 nicotinic acetylcholine receptor targeted treatment for the modulation of speech MMN indexed deviance detection in healthy volunteers: a pilot study

RATIONALE

The combination of CDP-choline, an α7 nicotinic acetylcholine receptor (α7 nAChR) agonist, with galantamine, a positive allosteric modulator of nAChRs, is believed to counter the fast desensitization rate of the α7 nAChRs and may be of interest for schizophrenia (SCZ) patients. Beyond the positive and negative clinical symptoms, deficits in early auditory prediction-error processes are also observed in SCZ. Regularity violations activate these mechanisms that are indexed by electroencephalography-derived mismatch negativity (MMN) event-related potentials (ERPs) in response to auditory deviance.

OBJECTIVES/METHODS

This pilot study in thirty-three healthy humans assessed the effects of an optimized α7 nAChR strategy combining CDP-choline (500 mg) with galantamine (16 mg) on speech-elicited MMN amplitude and latency measures. The randomized, double-blinded, placebo-controlled, and counterbalanced design with a baseline stratification method allowed for assessment of individual response differences.

RESULTS

Increases in MMN generation mediated by the acute CDP-choline/galantamine treatment in individuals with low baseline MMN amplitude for frequency, intensity, duration, and vowel deviants were revealed.

CONCLUSIONS

These results, observed primarily at temporal recording sites overlying the auditory cortex, implicate α7 nAChRs in the enhancement of speech deviance detection and warrant further examination with respect to dysfunctional auditory deviance processing in individuals with SCZ.

Auditory Mismatch Negativity in Youth Affected by Autism Spectrum Disorder With and Without Attenuated Psychosis Syndrome

The present study investigates the differences in auditory mismatch negativity (MMN) parameters given in a sample of young subjects with autism spectrum disorder (ASD, n = 37) with or without co-occurrent attenuated psychosis syndrome (APS). Our results show that ASD individuals present an MMN decreased amplitude and prolonged latency, without being influenced by concurrent APS. Additionally, when correlating the MMN indexes to clinical features, in the ASD + APS group, we found a negative correlation between the severity of autistic symptoms and the MMN latency in both frequency (f-MMN r = -0.810; p < 0.0001) and duration (d-MMN r = -0.650; p = 0.006) deviants. Thus, our results may provide a more informative characterization of the ASD sub-phenotype when associated with APS, highlighting the need for further longitudinal investigations.

Interaction of Background Noise and Auditory Hallucinations on Phonemic Mismatch Negativity (MMN) and P3a Processing in Schizophrenia

Auditory hallucinations (AHs) are among the cardinal symptoms of schizophrenia (SZ). During the presence of AHs aberrant activity of auditory cortices have been observed, including hyperactivation during AHs alone and hypoactivation when AHs are accompanied by a concurrent external auditory competitor. Mismatch negativity (MMN) and P3a are common ERPs of interest within the study of SZ as they are robustly reduced in the chronic phase of the illness. The present study aimed to explore whether background noise altered the auditory MMN and P3a in those with SZ and treatment-resistant AHs.

METHODS

MMN and P3a were assessed in 12 hallucinating patients (HPs), 11 non-hallucinating patients (NPs) and 9 healthy controls (HCs) within an auditory oddball paradigm. Standard (P = 0.85) and deviant (P = 0.15) stimuli were presented during three noise conditions: silence (SL), traffic noise (TN), and wide-band white noise (WN).

RESULTS

HPs showed significantly greater deficits in MMN amplitude relative to NPs in all background noise conditions, though predominantly at central electrodes. Conversely, both NPs and HPs exhibited significant deficits in P3a amplitude relative to HCs under the SL condition only.

SIGNIFICANCE

These findings suggest that the presence of AHs may specifically impair the MMN, while the P3a appears to be more generally impaired in SZ. That MMN amplitudes are specifically reduced for HPs during background noise conditions suggests HPs may have a harder time detecting changes in phonemic sounds during situations with external traffic or "real-world" noise compared to NPs.