Glutathione precursor, N-acetyl-cysteine, improves mismatch negativity in schizophrenia patients

Double blind, two dose, randomized, placebo-controlled, cross-over clinical trial of the positive allosteric modulator at the alpha7 nicotinic cholinergic receptor AVL-3288 in schizophrenia patients

Despite their theoretical rationale, nicotinic alpha-7 acetylcholine (nα₇) receptor agonists, have largely failed to demonstrate efficacy in placebo-controlled trials in schizophrenia. AVL-3288 is a nα₇ positive allosteric modulator (PAM), which is only active in the presence of the endogenous ligand (acetylcholine), and thus theoretically less likely to cause receptor desensitization. We evaluated the efficacy of AVL-3288 in a Phase 1b, randomized, double-blind, placebo-controlled, triple cross-over study. Twenty-four non-smoking, medicated, outpatients with schizophrenia or schizoaffective disorder and a Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) ≥62 were randomized. Each subject received 5 days of AVL-3288 (10, 30 mg) and placebo across three separate treatment weeks. The primary outcome measure was the RBANS total scale score, with auditory P50 evoked potential suppression the key target engagement biomarker. Secondary outcome measures include task-based fMRI (RISE task), mismatch negativity, the Scale for the Assessment of Negative Symptoms of Schizophrenia (SANS) and the Brief Psychiatric Rating Scale (BPRS). Twenty-four subjects were randomized and treated without any clinically significant treatment emergent adverse effects. Baseline RBANS (82 ± 17) and BPRS (41 ± 13) scores were consistent with moderate impairment. Primary outcomes were negative, with non-significant worsening for both active groups vs. placebo in the P50 and minimal between group changes on the RBANS. In conclusion, the results did not indicate efficacy of the compound, consistent with most prior results for the nα₇ target.

Abnormal Effective Connectivity Underlying Auditory Mismatch Negativity Impairments in Schizophrenia

BACKGROUND

Auditory mismatch negativity (MMN) is a translatable event-related potential biomarker, and its reduction in schizophrenia is associated with the severity of clinical symptoms. While MMN recorded at the scalp is generated by a distributed network of temporofrontal neural sources, the primary contributing sources and the dynamic interactions among sources underlying MMN impairments in schizophrenia have not been previously characterized.

METHODS

A novel data-driven analytic framework was applied to large cohorts of healthy comparison subjects (n = 449) and patients with schizophrenia (n = 589) to identify the independent contributing sources of MMN, characterize the patterns of effective connectivity underlying reduced MMN in patients, and explore the clinical significance of these abnormal source dynamics in schizophrenia.

RESULTS

A network of 11 independent contributing sources underlying MMN distributed across temporofrontal cortices was identified. Orderly shifts in peak source activity were detected in a steplike manner, starting at temporal structures and progressing across frontal brain regions. MMN reduction in patients was predominantly associated with reduced contributions from 3 frontal midline sources: orbitofrontal, anterior cingulate, and middle cingulate cortices. Patients showed increased connectivity from temporal to prefrontal regions in conjunction with decreased cross-hemispheric connectivity to prefrontal regions. The decreased connectivity strength of precentral to prefrontal regions in patients with schizophrenia was associated with greater severity of negative symptoms.

CONCLUSIONS

Alterations in the dynamic interactions among temporofrontal sources underlie MMN abnormalities in schizophrenia. These results advance our understanding of the neural substrates and temporal dynamics of normal and impaired information processing with novel applications for translatable biomarkers of neuropsychiatric disorders.

Meta-analysis of randomised controlled trials with N-acetylcysteine in the treatment of schizophrenia

OBJECTIVE

There is accumulating evidence that adjunctive treatment with N-acetylcysteine may be effective for schizophrenia. This study aimed to conduct a comprehensive meta-analysis examining the efficacy of randomised control trials investigating N-acetylcysteine as an adjunct treatment for schizophrenia and the first to investigate cognition as an outcome.

METHODS

We systematically reviewed Medline, EmCare, PsycINFO, Embase, CINAHL Complete, China Knowledge Resource Integrated Database and the Cochrane Clinical Trials online registry for randomised control trials of N-acetylcysteine for schizophrenia. We undertook pairwise meta-analyses of N-acetylcysteine vs placebo for psychosis symptoms and cognition.

RESULTS

Seven studies, including n = 220 receiving N-acetylcysteine and n = 220 receiving placebo, met inclusion criteria for the pairwise meta-analyses. Positive and Negative Syndrome Scale negative and total scores were significantly improved in the N-acetylcysteine group after 24 weeks of treatment. The cognitive domain of working memory improved with N-acetylcysteine supplementation.

CONCLUSION

Evidence supports the notion that N-acetylcysteine may be a useful adjunct to standard treatment for the improvement of schizophrenia symptoms, as well as the cognitive domain of working memory. Treatment effects were observed at the later time point (⩾24 weeks), suggesting that longer interventions are required for the success of N-acetylcysteine treatment.

Current challenges and possible future developments in personalized psychiatry with an emphasis on psychotic disorders

A personalized medicine approach seems to be particularly applicable to psychiatry. Indeed, considering mental illness as deregulation, unique to each patient, of molecular pathways, governing the development and functioning of the brain, seems to be the most justified way to understand and treat disorders of this medical category. In order to extract correct information about the implicated molecular pathways, data can be drawn from sampling phenotypic and genetic biomarkers and then analyzed by a machine learning algorithm. This review describes current difficulties in the field of personalized psychiatry and gives several examples of possibly actionable biomarkers of psychotic and other psychiatric disorders, including several examples of genetic studies relevant to personalized psychiatry. Most of these biomarkers are not yet ready to be introduced in clinical practice. In a next step, a perspective on the path personalized psychiatry may take in the future is given, paying particular attention to machine learning algorithms that can be used with the goal of handling multidimensional datasets.

Reduction of oxidative stress improves insulin signaling in cardiac tissue of obese mice

Objective

To evaluate the effects of oxidative stress on insulin signaling in cardiac tissue of obese mice.

Methods

Thirty Swiss mice were equally divided (n=10) into three groups: Control Group, Obese Group, and Obese Group Treated with N-acetylcysteine. After obesity and insulin resistance were established, the obese mice were treated with N-acetylcysteine at a dose of 50mg/kg daily for 15 days via oral gavage.

Results

Higher blood glucose levels and nitrite and carbonyl contents, and lower protein levels of glutathione peroxidase and phosphorylated protein kinase B were observed in the obese group when compared with their respective control. On the other hand, treatment with N-acetylcysteine was effective in reducing blood glucose levels and nitrite and carbonyl contents, and significantly increased protein levels of glutathione peroxidase and phosphorylated protein kinase B compared to the Obese Group.

Conclusion

Obesity and/or a high-lipid diet may result in oxidative stress and insulin resistance in the heart tissue of obese mice, and the use of N-acetylcysteine as a methodological and therapeutic strategy suggested there is a relation between them.

Destruction of ERP responses to deviance in an auditory oddball paradigm in amyloid infusion mice with memory deficits

The amyloid-β (Aβ) oligomer is considered one of the major pathogens responsible for neuronal and synaptic loss in Alzheimer’s disease (AD) brains. Although the neurotoxic mechanisms of Aβ have been widely investigated, experimental evidence for the direct linkage between neural signaling and cognitive impairments in association with peptide oligomers is lacking. Here, we conducted an auditory oddball paradigm utilizing an Aβ-infused Alzheimer’s disease mouse model and interpreted the results based on Y-maze behavioral tests. We acutely injected Aβ oligomers into the intracerebroventricular brain region of normal mice to induce Aβ-associated cognitive impairments. During the auditory oddball paradigm, electroencephalograms (EEG) were recorded from frontal and parietal cortex of Aβ-infused and control mice. The event-related potentials (ERPs) elicited by auditory stimuli showed no significant difference in Aβ-infused mice compared to control mice. On the other hand, the differential ERP signature elicited by oddball sound stimuli was destructed in the Aβ-infused mice group. We noticed that ERP traces to standard and deviant tones were not significantly different in the Aβ group, while the control group showed differences in the amplitude of ERP components. In particular, the difference in the first negative component (N1) between standard and deviant tone, which indexes the sensory memory system, was significantly reduced in the parietal cortex of Aβ-infused mice. These findings demonstrate the direct influence of Aβ oligomers on the functional integrity of cortical areas in vivo. Furthermore, the N1 amplitude difference may provide a potential marker of sensory memory deficits in a mouse model of AD and yield additional targets for drug assessment in AD.

Oxidation-reduction mechanisms in psychiatric disorders: A novel target for pharmacological intervention

While neurotransmitter dysfunction represents a key component in mental illnesses, there is now a wide agreement for a central pathophysiological hub that includes hormones, neuroinflammation, redox mechanisms as well as oxidative stress. With respect to oxidation-reduction (redox) mechanisms, preclinical and clinical evidence suggests that an imbalance in the pro/anti-oxidative homeostasis toward the increased production of substances with oxidizing potential may contribute to the etiology and manifestation of different psychiatric disorders. The substantial and continous demand for energy renders the brain highly susceptible to disturbances in its energy supply, especially following exposure to stressful events, which may lead to overproduction of reactive oxygen and nitrogen species under conditions of perturbed antioxidant defenses. This will eventually induce different molecular alterations, including extensive protein and lipid peroxidation, increased blood-brain barrier permeability and neuroinflammation, which may contribute to the changes in brain function and morphology observed in mental illnesses. This view may also reconcile different key concepts for psychiatric disorders, such as the neurodevelopmental origin of these diseases, as well as the vulnerability of selective cellular populations that are critical for specific functional abnormalities. The possibility to pharmacologically modulate the redox system is receiving increasing interest as a novel therapeutic strategy to counteract the detrimental effects of the unbalance in brain oxidative mechanisms. This review will describe the main mechanisms and mediators of the redox system and will examine the alterations of oxidative stress found in animal models of psychiatric disorders as well as in patients suffering from mental illnesses, such as schizophrenia and major depressive disorder. In addition, it will discuss studies that examined the effects of psychotropic drugs, including antipsychotics and antidepressants, on the oxidative balance as well as studies that investigated the effectiveness of a direct modulation of oxidative mechanisms in counteracting the behavioral and functional alterations associated with psychiatric disorders, which supports the promising role of the redox system as a novel therapeutic target for the improved treatment of brain disorders.

Progressive Impairment of Mismatch Negativity Is Reflective of Underlying Pathophysiological Changes in Patients With First-Episode Psychosis

BACKGROUND

Although mismatch negativity (MMN) is associated with the pathophysiology of schizophrenia, whether MMN progressively worsens during the initial years of psychotic disorder has not yet been sufficiently studied. We aimed to investigate whether longitudinal reduction of MMN occurs in patients with first-episode psychosis (FEP) and whether it is reflective of change in cognitive functioning or clinical status.

METHODS

MMN and the clinical status of 25 patients with FEP were measured and the Trail Making Test (TMT) was administered at baseline and reassessed after 1 year of usual treatment. The MMN of 25 matched healthy controls (HCs) was measured at baseline. Repeated-measures analysis of variance was used to compare MMNs at baseline among the groups, and paired t-test was utilized to compare the baseline and 1-year MMN amplitudes of FEP patients. To identify the association between changes in MMN and changes in cognitive, symptomatic, or functional status over 1 year, multiple regression analysis was used to control for other possible confounders.

RESULTS

MMN amplitudes at baseline were significantly attenuated in FEP patients compared to those in HC. The 1-year follow-up MMN amplitude decreased significantly at the Fz electrode site in the FEP group. Additionally, the decreased MMN amplitude significantly correlated with worsened TMT part B (TMT-B) performance over 1 year but did not correlate with symptomatic or functional improvement.

CONCLUSIONS

FEP patients with an MMN amplitude reduction showed worsening of cognitive functioning, which might reflect pathophysiological progression during the early years of a psychotic episode.

Neurophysiological Biomarkers in Schizophrenia-P50, Mismatch Negativity, and TMS-EMG and TMS-EEG

Impaired early auditory processing is a well characterized finding in schizophrenia that is theorized to contribute to clinical symptoms, cognitive impairment, and social dysfunction in patients. Two neurophysiological measures of early auditory processing, P50 gating ("P50") and mismatch negativity (MMN), which measure sensory gating and detection of change in auditory stimuli, respectively, are consistently shown to be impaired in patients with schizophrenia. Transcranial magnetic stimulation (TMS) may also be a potential method by which sensory processing can be assessed, since TMS paradigms can be used to measure GABA_B-mediated cortical inhibition that is linked with sensory gating. In this review, we examine the potential of P50, MMN and two TMS paradigms, cortical silent period (CSP) and long-interval intracortical inhibition (LICI), as endophenotypes as well as their ability to be used as predictive markers for interventions targeted at cognitive and psychosocial functioning. Studies consistently support a link between MMN, P50, and cognitive dysfunction, with robust evidence for a link between MMN and psychosocial functioning in schizophrenia as well. Importantly, studies have demonstrated that MMN can be used to predict performance in social and cognitive training tasks. A growing body of studies also supports the potential of MMN to be used as an endophenotype, and future studies are needed to determine if MMN can be used as an endophenotype specifically in schizophrenia. P50, however, has weaker evidence supporting its use as an endophenotype. While CSP and LICI are not as extensively investigated, growing evidence is supporting their potential to be used as an endophenotype in schizophrenia. Future studies that assess the ability of P50, MMN, and TMS neurophysiological measures to predict performance in cognitive and social training programs may identify markers that inform clinical decisions in the treatment of neurocognitive impairments in schizophrenia.

Effect of single dose N-acetylcysteine administration on resting state functional connectivity in schizophrenia

RATIONALE

There is interest in employing N-acetylcysteine (NAC) in the treatment of schizophrenia, but investigations of the functional signatures of its pharmacological action are scarce.

OBJECTIVES

The aim of this study was to identify the changes in resting-state functional connectivity (rs-FC) that occur following administration of a single dose of NAC in patients with schizophrenia. A secondary aim was to examine whether differences in rs-FC between conditions were mediated by glutamate metabolites in the anterior cingulate cortex (ACC).

METHODS

In a double-blind, placebo-controlled crossover design, 20 patients with schizophrenia had two MRI scans administered 7 days apart, following oral administration of either 2400 mg NAC or placebo. Resting state functional fMRI (rsfMRI) assessed the effect of NAC on rs-FC within the default mode network (DMN) and the salience network (SN). Proton magnetic resonance spectroscopy was used to measure Glx/Cr (glutamate plus glutamine, in ratio to creatine) levels in the ACC during the same scanning sessions.

RESULTS

Compared to the placebo condition, the NAC condition was associated with reduced within the DMN and SN, specifically between the medial pre-frontal cortex to mid frontal gyrus, and ACC to frontal pole (all p < 0.04). There were no significant correlations between ACC Glx/Cr and rs-FC in either condition (p > 0.6).

CONCLUSIONS

These findings provide preliminary evidence that NAC can reduce medial frontal rs-FC in schizophrenia. Future studies assessing the effects of NAC on rs-FC in early psychosis and on repeated administration in relation to efficacy would be of interest.

Multimodal prevention of first psychotic episode through N-acetyl-l-cysteine and integrated preventive psychological intervention in individuals clinically at high risk for psychosis: Protocol of a randomized, placebo-controlled, parallel-group trial

AIM

Meta-analyses indicate positive effects of both antipsychotic and cognitive-behavioural interventions in subjects clinically at high risk (CHR) for psychosis in terms of a delay or prevention of psychotic disorders. However, these effects have been limited regarding social functioning and the relative efficacy of both types of interventions remains unclear. Furthermore, neuroprotective substances seem to be a promising alternative agent in psychosis-prevention as they are associated with few and weak side-effects.

METHODS

In this multi-centre randomized controlled trial (RCT), we investigate the effects of two interventions on transition to psychosis and social functioning: (a) an integrated preventive psychological intervention (IPPI) including stress-/symptom-management and social-cognitive remediation; (b) N-acetyl-l-cysteine (NAC) as a pharmacological intervention with glutamatergic, neuroprotective and anti-inflammatory capabilities.

RESULTS

This is a double-blind, placebo-controlled RCT with regard to NAC and a single-blind RCT with regard to IPPI using a 2 × 2-factorial design to investigate the individual and combined preventive effects of both interventions. To this aim, a total of 200 CHR subjects will be randomized stratified by site to one of four conditions: (a) IPPI and NAC; (b) IPPI and Placebo; (c) NAC and psychological stress management; (d) Placebo and psychological stress management. Interventions are delivered over 26 weeks with a follow-up period of 12 months.

CONCLUSION

This paper reports on the rationale and protocol of an indicated prevention trial to detect the most effective and tolerable interventions with regard to transition to psychosis as well as improvements in social functioning, and to evaluate the synergistic effects of these interventions.

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.

ENACT: a protocol for a randomised placebo-controlled trial investigating the efficacy and mechanisms of action of adjunctive N-acetylcysteine for first-episode psychosis

BACKGROUND

First-episode psychosis (FEP) may lead to a progressive, potentially disabling and lifelong chronic illness; however, evidence suggests that the illness course can be improved if appropriate treatments are given at the early stages. Nonetheless, the efficacy of antipsychotic medications is suboptimal, particularly for negative and cognitive symptoms, and more efficacious and benign treatments are needed. Previous studies have shown that the antioxidant amino acid N-acetylcysteine (NAC) reduces negative symptoms and improves functioning in chronic schizophrenia and bipolar disorder. Research is scarce as to whether NAC is beneficial earlier in the course of illness. The primary aim of this study is to determine the efficacy of treatment with adjunctive NAC (2 g/day for 26 weeks) compared with placebo to improve psychiatric symptoms in young people experiencing FEP. Secondary aims are to explore the neurobiological mechanisms underpinning NAC and how they relate to various clinical and functional outcomes at 26- and 52-week follow-ups.

METHODS/DESIGN

ENACT is a 26-week, randomised controlled trial of adjunctive NAC versus placebo, with a 26-week non-treatment follow-up period, for FEP. We will be recruiting 162 young people aged 15-25 years who have recently presented to, and are being treated at, the Early Psychosis Prevention and Intervention Centre, Melbourne, Australia. The primary outcome is the Total Score on the Positive and Negative Syndrome Scale which will be administered at baseline, and weeks 4, 8, 12, 26 (primary endpoint), and 52 (end of study). Secondary outcomes include: symptomatology, functioning, quality of life, neurocognition, blood-derived measures of: inflammation, oxidative and nitrosative stress, and magnetic resonance spectroscopy measures of glutathione concentration.

DISCUSSION

Targeted drug development for FEP to date has generally not involved the exploration of neuroprotective agents. This study has the potential to offer a new, safe, and efficacious treatment for people with FEP, leading to better treatment outcomes. Additionally, the neuroprotective dimension of this study may lead to a better long-term prognosis for people with FEP. It has the potential to uncover a novel treatment that targets the neurobiological mechanisms of FEP and, if successful, will be a major advance for psychiatry.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry, ID: ACTRN12618000413224. Registered on 21 March 2018.

Validation of oxidative stress assay for schizophrenia

Accumulating evidence implicates oxidative stress in a range of diseases, yet no objective measurement has emerged that characterizes the global nature of oxidative stress. Previously, we reported a measurement that employs the moderately strong oxidant iridium (Ir) to probe the oxidative damage in a serum sample and reported that in a small study (N = 15) the Ir-reducing capacity assay could distinguish schizophrenia from healthy control groups based on their levels of oxidative stress. Here, we used a larger sample size to evaluate the Ir-reducing capacity assay to assess its ability to discriminate the schizophrenia (N = 73) and healthy control groups (N = 45). Each serum sample was measured (in triplicate) at three different times that were separated by several weeks. The Intraclass Correlation Coefficient (ICC = 0.69) for these repeated measurements indicates the assay detects stable components in the sample (i.e., it is not detecting transient reactive species or air-oxidizable serum components). Correlations between the Ir-reducing capacity assay and independently-measured total serum protein levels (r = +0.74, p < 2.2 × 10^-16) suggest the assay is detecting information in the protein pool. For cross-validation of the discrimination ability, we used machine learning and receiver operating characteristic (ROC) analysis. After adjusting for potential confounders (age and smoking status), an area under the curve (AUC) of ROC curve was calculated to be 0.89 (p = 9.3 × 10^-5). In conclusion, this validation indicates the Ir-reducing capacity assay provides a simple global measure of oxidative stress, and further supports the hypothesis that oxidative stress is linked with schizophrenia.

N-Acetyl-Cysteine Supplementation Improves Functional Connectivity Within the Cingulate Cortex in Early Psychosis: A Pilot Study

BACKGROUND

There is increasing evidence that redox dysregulation, which can lead to oxidative stress and eventually to impairment of oligodendrocytes and parvalbumin interneurons, may underlie brain connectivity alterations in schizophrenia. Accordingly, we previously reported that levels of brain antioxidant glutathione in the medial prefrontal cortex were positively correlated with increased functional connectivity along the cingulum bundle in healthy controls but not in early psychosis patients. In a recent randomized controlled trial, we observed that 6-month supplementation with a glutathione precursor, N-acetyl-cysteine, increased brain glutathione levels and improved symptomatic expression and processing speed.

METHODS

We investigated the effect of N-acetyl-cysteine supplementation on the functional connectivity between regions of the cingulate cortex, which have been linked to positive symptoms and processing speed decline. In this pilot study, we compared structural connectivity and resting-state functional connectivity between early psychosis patients treated with 6-month N-acetyl-cysteine (n = 9) or placebo (n = 11) supplementation with sex- and age-matched healthy control subjects (n = 74).

RESULTS

We observed that 6-month N-acetyl-cysteine supplementation increases functional connectivity along the cingulum and more precisely between the caudal anterior part and the isthmus of the cingulate cortex. These functional changes can be partially explained by an increase of centrality of these regions in the functional brain network.

CONCLUSIONS

N-acetyl-cysteine supplementation has a positive effect on functional connectivity within the cingulate cortex in early psychosis patients. To our knowledge, this is the first study suggesting that increased brain glutathione levels via N-acetyl-cysteine supplementation may improve brain functional connectivity.

Elucidating the glutamatergic processes underlying mismatch negativity deficits in early stage bipolar disorder and schizophrenia: A combined 1H-MRS and EEG study

Impairments in mismatch negativity (MMN) in schizophrenia are well-established; these findings have been extended to show impairments at early illness stages and in bipolar disorder. A substantial literature supports MMN as an index of NMDA receptor output, however, few studies have conducted in vivo assessments to elucidate the neurochemical underpinnings of MMN. Sixty young (16-33 years) participants with bipolar disorder (n = 47) or schizophrenia (n = 13) underwent ¹H-MRS and MMN assessment. Glutamate over creatine (Glu/Cr) levels in the anterior cingulate cortex (ACC) and hippocampus were determined and MMN was measured frontally and temporally. Correlational analyses assessed the relationship between MMN amplitudes and Glu/Cr. Any significant relationships were assessed for specificity with a follow up correlation analysis of MMN and n-acetyleaspartate (NAA/Cr). No associations between frontal or temporal MMN and ACC or hippocampal Glu/Cr were noted in the bipolar group. In the schizophrenia group, frontal and right temporal MMN amplitudes corresponded with increased ACC Glu/Cr at the trend-level. Right temporal MMN was similarly significantly associated with NAA/Cr. MMN was not associated with hippocampal Glu/Cr. This work provides in vivo evidence that glutamatergic processes may underlie MMN generation in early stage schizophrenia but not in early stage bipolar disorder suggesting differences in the MMN mechanism in these groups. The negative association between ACC Glu/Cr and MMN is consistent with findings of reduced MMN and increased in vivo glutamatergic neurometabolite levels in early stage schizophrenia. Furthermore, these results indicate that examining in vivo NAA/Cr may have provide additional insights into the MMN mechanism in schizophrenia.

Galantamine-Memantine Combination as an Antioxidant Treatment for Schizophrenia

PURPOSE OF REVIEW

The objective of this article is to highlight the potential role of the galantamine-memantine combination as a novel antioxidant treatment for schizophrenia.

RECENT FINDINGS

In addition to the well-known mechanisms of action of galantamine and memantine, these medications also have antioxidant activity. Furthermore, an interplay exists between oxidative stress, inflammation (redox-inflammatory hypothesis), and kynurenine pathway metabolites. Also, there is an interaction between brain-derived neurotrophic factor and oxidative stress in schizophrenia. Oxidative stress may be associated with positive, cognitive, and negative symptoms and impairments in white matter integrity in schizophrenia. The antipsychotic-galantamine-memantine combination may provide a novel strategy in schizophrenia to treat positive, cognitive, and negative symptoms.

SUMMARY

A "single antioxidant" may be inadequate to counteract the complex cascade of oxidative stress. The galantamine-memantine combination as "double antioxidants" is promising. Hence, randomized controlled trials are warranted with the antipsychotic-galantamine-memantine combination with oxidative stress and antioxidant biomarkers in schizophrenia.

Recycling N-acetylcysteine: A review of evidence for adjunctive therapy in schizophrenia

Introduction

All symptoms in schizophrenia may impact functioning. Although Food and Drug Administration-approved medications typically benefit positive symptoms, negative symptoms are generally refractory to medication interventions. N-acetylcysteine's (NAC) influence on glutamatergic neurotransmission has been established. An emerging body of research has attempted to correlate this action with reduction in symptom severity, evaluating response in positive, negative, and cognitive symptom domains.

Methods

A literature review was performed to analyze available data on NAC intervention and improvement in the positive, negative, and cognitive symptom domains in patients with schizophrenia. Quality of evidence was systematically assessed to determine level of certainty in results.

Results

Three randomized controlled trials were identified. Across studies, negative symptoms decreased more with NAC compared to placebo; ranging between 11.9% and 24.1%. The assessment determined a low level of certainty regarding benefit of NAC on negative and cognitive symptoms and moderate certainty for NAC regarding findings of side effects and lack of benefit on positive symptoms.

Discussion

Consistent reporting of benefit in negative symptoms is found across studies of NAC intervention. These improvements are notable for symptoms that have generally remained refractory to medication intervention. Inconsistent benefit was reported in positive and cognitive symptoms. GRADE (grading of recommendations assessment, development and evaluation) assessment of current evidence indicates a low certainty of benefit for negative symptoms with standard use of NAC in patients with schizophrenia. However, a trial of this low-risk intervention may be warranted in patients with resistant negative symptoms and subsequent impaired functioning despite appropriate antipsychotic therapy as they may experience additional benefit in this symptom domain.

NMDA Receptor Antagonist Effects on Speech-Related Mismatch Negativity and Its Underlying Oscillatory and Source Activity in Healthy Humans

Background: Previous studies in schizophrenia have consistently shown that deficits in the generation of the auditory mismatch negativity (MMN) – a pre-attentive, event-related potential (ERP) typically elicited by changes to simple sound features – are linked to N-methyl-D-aspartate (NMDA) receptor hypofunction. Concomitant with extensive language dysfunction in schizophrenia, patients also exhibit MMN deficits to changes in speech but their relationship to NMDA-mediated neurotransmission is not clear. Accordingly, our study aimed to investigate speech MMNs in healthy humans and their underlying electrophysiological mechanisms in response to NMDA antagonist treatment. We also evaluated the relationship between baseline MMN/electrocortical activity and emergent schizophrenia-like symptoms associated with NMDA receptor blockade.

Methods: In a sample of 18 healthy volunteers, a multi-feature Finnish language paradigm incorporating changes in syllables, vowels and consonant stimuli was used to assess the acute effects of the NMDA receptor antagonist ketamine and placebo on the MMN. Further, measures of underlying neural activity, including evoked theta power, theta phase locking and source-localized current density in cortical regions of interest were assessed. Subjective symptoms were assessed with the Clinician Administered Dissociative States Scale (CADSS).

Results: Participants exhibited significant ketamine-induced increases in psychosis-like symptoms and depending on temporal or frontal recording region, co-occurred with reductions in MMN generation in response to syllable frequency/intensity, vowel duration, across vowel and consonant deviants. MMN attenuation was associated with decreases in evoked theta power, theta phase locking and diminished current density in auditory and inferior frontal (language-related cortical) regions. Baseline (placebo) MMN and underlying electrophysiological features associated with the processing of changes in syllable intensity correlated with the degree of psychotomimetic response to ketamine.

Conclusion: Ketamine-induced impairments in healthy human speech MMNs and their underlying electrocortical mechanisms closely resemble those observed in schizophrenia and support a model of dysfunctional NMDA receptor-mediated neurotransmission of language processing deficits in schizophrenia.

N-methyl-d-aspartate-type glutamate receptor modulators and related medications for the enhancement of auditory system plasticity in schizophrenia

Deficits in N-methyl-d-aspartate-type (NMDAR) function contribute to cognitive deficits in schizophrenia, particularly dysfunction in neuroplasticity, defined as reduced learning during training on exercises that place implicit, increasing demands on early sensory (auditory and visual) information processing. Auditory mismatch negativity (MMN) can be both a target engagement biomarker for the NMDAR and a proxy measure of neurophysiological plasticity. This review covers the evidence for using NMDAR modulator and related compounds for enhancement of cognition, with a particular focus on early auditory processing/plasticity. Compounds covered include glycine site agonists, glycine and system A-type transporter inhibitors, d-amino acid oxidase inhibitors, memantine and nicotinic alpha-7 acetylcholine receptor agonists. As opposed to daily treatment studies focusing on schizophrenia in general, intermittent, non-daily treatment combining NMDAR modulators with neuroplasticity-based paradigms, using MMN as target-engagement biomarkers show promise as treatments to both remediate plasticity deficits and overall functional deficits.

Effects of acute N-acetylcysteine challenge on cortical glutathione and glutamate in schizophrenia: A pilot in vivo proton magnetic resonance spectroscopy study

Findings from in vivo brain proton magnetic resonance spectroscopy (1H MRS) and preclinical studies have suggested region- and medication status-dependent increases in glutamate (Glu) levels and deficiencies in glutathione (GSH) levels in schizophrenia. N-acetylcysteine (NAC), a GSH synthesis precursor, has demonstrated modest clinical benefit in schizophrenia. The objective of this study was to examine the effects of acute administration of NAC on GSH and Glu levels measured with 1H MRS in 19 patients with schizophrenia and 20 healthy control subjects. Levels of GSH were acquired in dorsal anterior cingulate cortex (dACC), and those of Glu in dACC and medial prefrontal cortex (mPFC), at baseline and 60 min following acute oral administration of 2400 mg of NAC. No differences in the levels of GSH or Glu were found at baseline or following NAC administration between patients with schizophrenia and control subjects in either of the targeted brain regions. Future studies measuring GSH levels in brain regions previously found to exhibit glutamatergic abnormalities or using genetic polymorphisms, while controlling for the age and medication status of the cohorts, are warranted to better identify groups of patients more likely to respond to NAC and its mode of action and mechanisms.

Abnormal development of early auditory processing in 22q11.2 Deletion Syndrome

The 22q11.2 Deletion Syndrome (22q11.2 DS) is one of the highest genetic risk factors for the development of schizophrenia spectrum disorders. In schizophrenia, reduced amplitude of the frequency mismatch negativity (fMMN) has been proposed as a promising neurophysiological marker for progressive brain pathology. In this longitudinal study in 22q11.2 DS, we investigate the progression of fMMN between childhood and adolescence, a vulnerable period for brain maturation. We measured evoked potentials to auditory oddball stimuli in the same sample of 16 patients with 22q11.2 DS and 14 age-matched controls in childhood and adolescence. In addition, we cross-sectionally compared an increased sample of 51 participants with 22q11.2 DS and 50 controls divided into two groups (8-14 and 14-20 years). The reported results are obtained using the fMMN difference waveforms. In the longitudinal design, the 22q11.2 deletion carriers exhibit a significant reduction in amplitude and a change in topographic patterns of the mismatch negativity response from childhood to adolescence. The same effect, reduced mismatch amplitude in adolescence, while preserved during childhood, is observed in the cross-sectional study. These results point towards functional changes within the brain network responsible for the fMMN. In addition, the adolescents with 22q11.2 DS displayed a significant increase in amplitude over central electrodes during the auditory N1 component. No such differences, reduced mismatch response nor increased N1, were observed in the typically developing group. These findings suggest different developmental trajectories of early auditory sensory processing in 22q11.2 DS and functional changes that emerge during the critical period of increased risk for schizophrenia spectrum disorders.

MEGA-PRESS and PRESS measure oxidation of glutathione in a phantom

PURPOSE

Investigate the possibility of measuring changes in glutathione (GSH) concentration using the MRS PRESS and MEGA-PRESS sequences by tracking the natural oxidation of GSH, and to examine the accuracy of the two methods.

METHODS

122 GSH edited MEGA-PRESS and PRESS acquisitions were acquired on a "braino" based phantom +3.0 mM GSH during a period of 11 days. All spectra were analyzed in LCModel. (The MEGA-PRESS data were first preprocessed in Matlab). Degradation curves were modeled. A one year follow-up on the same phantom and measurements from a similar phantom without GSH and one pure GSH phantom were also included.

RESULTS

Both MEGA-PRESS and PRESS showed degradation of the measured GSH signal. Modeling the exponential decay of the GSH signal in MEGA-PRESS and PRESS gave for t = 0; 2.9 i.u. for MEGA-PRESS and 2.3 i.u. for PRESS. As t increased, the GSH concentration converged to zero for MEGA-PRESS but not for PRESS (0.7 i.u.). GSH for the one year follow up were 0.0 i.u. for MEGA-PRESS and 0.6 i.u. for PRESS. Similar phantom without GSH yielded 0.0 i.u. for both MEGA-PRESS and PRESS.

CONCLUSION

It is possible to measure changes in GSH concentration in a phantom using both PRESS and MEGA-PRESS techniques, however the PRESS spectrum appears to include oxidized GSH (GSSG). In addition, GSH edited MEGA-PRESS measurement gives more precise values at lower GSH concentrations.

Antipsychotic-minocycline-acetylcysteine combination for positive, cognitive, and negative symptoms of schizophrenia

Preclinical evidence shows that the minocycline and N-acetylcysteine (NAC) combination synergistically improved cognition. Meta-analyses of randomized controlled trials (RCTs) with minocycline and NAC have shown some efficacy signal for positive, cognitive, and negative symptoms of schizophrenia. Hence, the combination may be more effective than either medication alone. The objective of this article is to highlight the potential role of the minocycline-NAC combination for the treatment of schizophrenia. The antipsychotic-minocycline-NAC combination is promising and has the potential to concurrently treat positive, cognitive, and primary negative symptoms. RCTs are warranted with the minocycline-NAC combination to address the unmet clinical need in schizophrenia.

Overview on the Effects of N-Acetylcysteine in Neurodegenerative Diseases

N-acetylcysteine (NAC), which is an acetylated cysteine compound, has aroused scientific interest for decades due to its important medical applications. It also represents a nutritional supplement in the human diet. NAC is a glutathione precursor and shows antioxidant and anti-inflammatory activities. In addition to the uses quoted in the literature, NAC may be considered helpful in therapies to counteract neurodegenerative and mental health diseases. Furthermore, this compound has been evaluated for its neuroprotective potential in the prevention of cognitive aging dementia. NAC is inexpensive, commercially available and no relevant side effects were observed after its administration. The purpose of this paper is to give an overview on the effects and applications of NAC in Parkinson's and Alzheimer's disorders and in neuropathic pain and stroke.

Overexpression of kynurenic acid and 3-hydroxyanthranilic acid after rat traumatic brain injury

Using an immunohistochemical technique, we have studied the distribution of kynuneric acid (KYNA) and 3-hydroxyanthranilic acid (3-HAA) in a rat brain injury model (trauma). The study was carried out inducing a cerebral ablation of the frontal motor cortex. Two mouse monoclonal specific antibodies previously developed by our group directed against KYNA and 3-HAA were used. In control animals (sham-operated), the expression of both KYNA and 3-HAA was not observed. In animals in which the ablation was performed, the highest number of immunoreactive cells containing KYNA or 3-HAA was observed in the region surrounding the lesion and the number of these cells decreased moving away from the lesion. KYNA and 3-HAA were also observed in the white matter (ipsilateral side) located close to the injured region and in some cells placed in the white matter of the contralateral side. The distribution of KYNA and 3-HAA perfectly matched with the peripheral injured regions. The results found were identical independently of the perfusion date of animals (17, 30 or 54 days after brain injury). For the first time, the presence of KYNA and 3-HAA has been described in a rat trauma model. Moreover, by using a double immunocytochemistry protocol, it has been demonstrated that both metabolites were located in astrocytes. The findings observed suggest that, in cerebral trauma, KYNA and 3-HAA are involved in tissue damage and that these compounds could act, respectively, as a neuroprotector and a neurotoxic. This means that, in trauma, a counterbalance occurs and that a regulation of the indoleamine 2,3 dioxygenase (IDO) pathway could be required after a brain injury in order to decrease the deleterious effects of ending metabolites (the neurotoxic picolinic acid). Moreover, the localization of KYNA and 3-HAA in the contralateral side of the lesion suggests that the IDO pathway is also involved in the sprouting and pathfinding that follows a traumatic brain injury.

Glutamatergic Deficits in Schizophrenia - Biomarkers and Pharmacological Interventions within the Ketamine Model

Background:

The observation that N-methyl-D-aspartate glutamate receptor (NMDAR) antagonists such as ketamine transiently induce schizophrenia-like positive, negative and cognitive symptoms has led to a paradigm shift from dopaminergic to glutamatergic dysfunction in pharmacological models of schizophrenia. NMDAR hypofunction can explain many schizophrenia symptoms directly due to excitatory-to-inhibitory (E/I) imbalance, but also dopaminergic dysfunction itself. However, so far no new drug targeting the NMDAR has been successfully approved. In the search for possible biomarkers it is interesting that ketamine-induced psychopathological changes in healthy participants were accompanied by altered electro-(EEG), magnetoencephalographic (MEG) and functional magnetic resonance imaging (fMRI) signals.

Methods:

We systematically searched PubMed/Medline and Web of Knowledge databases (January 2006 to July 2017) to identify EEG/MEG and fMRI studies of the ketamine model of schizophrenia with human subjects. The search strategy identified 209 citations of which 46 articles met specified eligibility criteria.

Results:

In EEG/MEG studies, ketamine induced changes of event-related potentials, such as the P300 potential and the mismatch negativity, similar to alterations observed in schizophrenia patients. In fMRI studies, alterations of activation were observed in different brain regions, most prominently within the anterior cingulate cortex and limbic structures as well as task-relevant brain regions. These alterations were accompanied by changes in functional connectivity, indicating a balance shift of the underlying brain networks. Pharmacological treatments did alter ketamine-induced changes in EEG/MEG and fMRI studies to different extents.

Conclusion:

This review highlights the potential applicability of the ketamine model for schizophrenia drug development by offering the possibility to assess the effect of pharmacological agents on schizophrenia-like symptoms and to find relevant neurophysiological and neuroimaging biomarkers.

N-acetylcysteine add-on treatment leads to an improvement of fornix white matter integrity in early psychosis: a double-blind randomized placebo-controlled trial

Mechanism-based treatments for schizophrenia are needed, and increasing evidence suggests that oxidative stress may be a target. Previous research has shown that N-acetylcysteine (NAC), an antioxidant and glutathione (GSH) precursor almost devoid of side effects, improved negative symptoms, decreased the side effects of antipsychotics, and improved mismatch negativity and local neural synchronization in chronic schizophrenia. In a recent double-blind randomized placebo-controlled trial by Conus et al., early psychosis patients received NAC add-on therapy (2700 mg/day) for 6 months. Compared with placebo-treated controls, NAC patients showed significant improvements in neurocognition (processing speed) and a reduction of positive symptoms among patients with high peripheral oxidative status. NAC also led to a 23% increase in GSH levels in the medial prefrontal cortex (GSH_mPFC) as measured by ¹H magnetic resonance spectroscopy. A subgroup of the patients in this study were also scanned with multimodal MR imaging (spectroscopy, diffusion, and structural) at baseline (prior to NAC/placebo) and after 6 months of add-on treatment. Based on prior translational research, we hypothesized that NAC would protect white matter integrity in the fornix. A group × time interaction indicated a difference in the 6-month evolution of white matter integrity (as measured by generalized fractional anisotropy, gFA) in favor of the NAC group, which showed an 11% increase. The increase in gFA correlated with an increase in GSH_mPFC over the same 6-month period. In this secondary study, we suggest that NAC add-on treatment may be a safe and effective way to protect white matter integrity in early psychosis patients.

Effects of N-acetylcysteine on brain glutamate levels and resting perfusion in schizophrenia

RATIONALE

N-Acetylcysteine (NAC) is currently under investigation as an adjunctive treatment for schizophrenia. The therapeutic potential of NAC may involve modulation of brain glutamate function, but its effects on brain glutamate levels in schizophrenia have not been evaluated.

OBJECTIVES

The aim of this study was to examine whether a single dose of NAC can alter brain glutamate levels. A secondary aim was to characterise its effects on regional brain perfusion.

METHODS

In a double-blind placebo-controlled crossover study, 19 patients with a diagnosis of schizophrenia underwent two MRI scans, following oral administration of 2400 mg NAC or matching placebo. Proton magnetic resonance spectroscopy was used to investigate the effect of NAC on glutamate and Glx (glutamate plus glutamine) levels scaled to creatine (Cr) in the anterior cingulate cortex (ACC) and in the right caudate nucleus. Pulsed continuous arterial spin labelling was used to assess the effects of NAC on resting cerebral blood flow (rCBF) in the same regions.

RESULTS

Relative to the placebo condition, the NAC condition was associated with lower levels of Glx/Cr, in the ACC (P < 0.05), but not in the caudate nucleus. There were no significant differences in CBF in the NAC compared to placebo condition.

CONCLUSIONS

These data provide preliminary evidence that NAC can modulate ACC glutamate in patients with schizophrenia. In contrast, physiological effects of NAC on the brain were not detectable as between session changes in rCBF. Future studies assessing the effects of a course of treatment with NAC on glutamate metabolites in schizophrenia are indicated.

Neurocognitive effects of an omega-3 fatty acid and vitamins E+C in schizophrenia: A randomised controlled trial

There is need for more efficient treatment of neurocognitive deficits in schizophrenia. In this 16 weeks randomised, placebo-controlled trial, we examined neurocognitive effects of adding ethyl-eicosapentaenoate 2g/day and/or vitamins E 364mg/day + C 1000mg/day to antipsychotics in 53 patients aged 18-39 years with acute schizophrenia. For the sake of validating neurocognitive tests, healthy subjects, not taking trial drugs, were also included in the study. Ethyl-EPA given alone to patients with low baseline RBC polyunsaturated fatty acids (PUFA), and Vitamins E+C given alone to high PUFA patients, impaired sustained attention (Continuous Performance Test, CPT-IP d prime score), standardised effect sizes d = 0.78 and d = 0.69, respectively. These adverse effects were paralleled by excessive increases in long-chain PUFA and serum alpha-tocopherol, respectively. They were counteracted by combining ethyl-EPA and vitamins, d = 0.80 and d = 0.74 in low and high PUFA patients, respectively. No other neurocognitive tests yielded significant results. Plausible mechanisms of harmful effects are oxidative stress and lipid raft disruption.

Effects of 12-month, double-blind N-acetyl cysteine on symptoms, cognition and brain morphology in early phase schizophrenia spectrum disorders

BACKGROUND

Currently approved medications for schizophrenia are relatively ineffective for negative symptoms and cognitive impairment. N-Acetyl Cysteine (NAC) is a neuroprotective agent that improved general symptoms, cognitive impairment and negative symptoms in some but not all studies, but failed to improve positive symptoms in patients with schizophrenia. Progressive brain mass loss (PBML) has been consistently observed in early phase schizophrenia. NAC mitigates the deleterious effects oxidative stress, inflammation and glutamatergic excitotoxicity and these three pathological processes are hypothesized to contribute to PBML.

METHODS

In this study, we assessed the effects NAC (3600mg/day) in a 52-week, double-blind, placebo controlled trial on symptoms, and cognition in early phase schizophrenia spectrum disorders (N=60). In the context of the clinical trial, we explored the effects of NAC on brain morphology.

RESULTS

NAC significantly improved (time×group) PANSS total (F=14.7, p<0.001), negative (F=5.1, p=0.024) and disorganized thought (F=13.7, p<0.001) symptom scores. NAC failed to improve PANSS positive symptoms and BACS cognitive scores. In preliminary analyses, baseline right (r=-0.48, p=0.041) and left (r=-0.45, p=0.018) total cortical thickness, and thickness in other cortical regions, were associated with NAC related improvement in PANSS total scores, but NAC, as compared to placebo, did not significantly impact brain morphology over the study treatment period.

CONCLUSIONS

These results replicate some but not all previous findings of NAC efficacy. Preliminary results suggest that NAC's symptom effects may be related to structural integrity, but NAC failed to demonstrate treatment effects on longitudinal measures of brain morphology. ClinicalTrials.gov Identifier: NCT01339858.

A Spectroscopic Study of Interaction of Auricyanide with n-Acetylcysteine

Interaction of auricyanide, an important metabolite of anti-arthritic gold-based drug auranofin, was studied in vitro with a pharmacologically active ligand n-acetylcysteine with a view to understand reactivity of gold in vivo. Formation of reduction product aurocyanide occurred through mono- and di-n-acetylcysteine-substituted intermediates. The product and intermediates were identified and monitored spectrophotometrically and by electrospray ionization mass spectrometry. This study suggests successive substitution with n-acetylcysteine through trans effect. At equimolar concentrations of auricyanide and n-acetylcysteine, only mono-substituted mixed-ligand complex was formed. Substitution of the data obtained to various kinetic models suggested that the reaction orders are 0.6 in terms of n-acetylcysteine, 1.5 in terms of auricyanide, and 2 overall. The intermediates detected in this work may help to synthesize more effective and less toxic gold drugs.

Association between mismatch negativity and global functioning is specific to duration deviance in early stages of psychosis

BACKGROUND

Mismatch negativity (MMN) is a candidate biomarker for early stages of psychosis. Although an association among duration MMN (dMMN), cognitive deficits, and functional outcome in chronic schizophrenia has been shown by a large-scale study, the effects of deviant type and clinical stages have not been investigated.

METHODS

We investigated the relationships among dMMN, frequency MMN (fMMN), global functioning, and cognitive function in early stages of psychosis. The participants included 26 individuals with recent-onset schizophrenia (ROSZ), 30 individuals with ultra-high risk (UHR), and 20 healthy controls.

RESULTS

The correlational analyses revealed that dMMN amplitude, which was impaired in the ROSZ group compared to the healthy controls, correlated with global functioning (Global Assessment of Functioning-Functioning scale) in the ROSZ (r=-0.45) and UHR (r=-0.37) groups. The amplitude of fMMN, which did not differ among the groups, correlated with working memory (r=-0.57) only in the ROSZ group. The path analyses indicated that dMMN had a direct effect on global functioning in the ROSZ and UHR groups while fMMN had a direct effect on working memory only in the ROSZ group.

CONCLUSIONS

Our findings suggested that the association between MMN and global functioning was specific to the duration deviant and was already present in early stages of psychosis. These findings confirm the usefulness of dMMN as a biological marker of early psychosis to guide treatment interventions.

Therapeutic effect of adjunctive N-acetyl cysteine (NAC) on symptoms of chronic schizophrenia: A double-blind, randomized clinical trial

BACKGROUND

Schizophrenia is one of the most disabling psychiatric syndromes with the prevalence of 1% in the general population. Despite availability of various antipsychotics, negative symptoms and cognitive impairment are difficult to treat. In addition antipsychotic monotherapy is not effective in most of these patients. Current evidence indicates the roles of glutamatergic system in this disorder. N-acetyl cysteine (NAC) also increases extracellular glutamate. This study was conducted to evaluate the clinical effects of oral NAC as an add-on to maintenance medication for the treatment of chronic schizophrenia.

MATERIALS AND METHODS

This 12-week, double-blind, randomized, placebo-controlled, clinical trial was performed to determine the effectiveness of 1200mg N-acetyl cysteine as an adjunctive treatment with conventional antipsychotic medications in 84 patients with chronic schizophrenia. The subjects were evaluated with the Positive and Negative Syndrome Scale (PANSS), Mini-Mental State Examination (MMSE), and a standard neuropsychological screening test. Data were analyzed with SPSS-16 software.

RESULTS

NAC-treated patients showed significantly improvement in the positive (F=5.47, P=0.02) and negative (F=0.20, df=1) PANSS subscale. Also the general and total PANSS score of NAC group declined over times whilst it was increased for placebo group. Regarding cognitive functions, improvement was observed in some explored areas, such as attention, short-term and working memory, executive functioning and speed of processing. There was no significant difference between the 2 groups in the frequency of adverse effects.

CONCLUSION

The present study detected improvement in positive, negative, general and total psychopathology symptoms as well as cognitive performance with NAC treatment. It is also well-tolerated, safe and easy-to-use agent as an effective therapeutic strategy to improve outcome in schizophrenia treatment.

Role of Novel Dietary Supplement N-acetyl Cysteine in Treating Negative Symptoms in Schizophrenia: A 6-Month Follow-up Study

BACKGROUND

Abnormal metabolism of dopamine and glutamate in schizophrenia induces oxidative stress that is exacerbated by brain glutathione (GSH) deficiency. N-acetyl cysteine (NAC) increases brain GSH levels and is being used as an adjunctive agent in patients with schizophrenia. This open-label exploratory study in a naturalistic setting was conceived to examine the efficacy of NAC augmentation in treating negative syndrome in schizophrenia.

AIMS

To examine the efficacy of add-on NAC (1200 mg) in treating negative symptoms measured using Scale for the Assessment of Negative Symptoms (SANS) and clinical global impression (CGI) at baseline and 24 weeks.

SUBJECTS AND METHODS

In a 24-week feasibility study with open-label design, thirty patients with the International Classification of Diseases-Tenth Edition diagnosis of schizophrenia were recruited. Eligible patients were required to have been treated with stable dose of clozapine or amisulpride for negative symptoms for a minimum period of 8 weeks were selected for the study. The subjects were assigned to receive NAC (1.2 g/day) as an add-on treatment. Severity of negative symptoms was measured using SANS and CGI-severity at baseline and improvement with NAC measured using CGI-improvement at 24 weeks. Serum interleukin-6 was assessed before NAC initiation at baseline.

RESULTS

NAC augmentation showed a significantly greater improvement in negative symptoms on total SANS and CGI scores at 24 weeks.

CONCLUSIONS

NAC may be effective as an adjunct for the treatment of negative symptoms in schizophrenia.

Natural Medicines for Psychotic Disorders: A Systematic Review

Patients with psychotic disorders regularly use natural medicines, although it is unclear whether these are effective and safe. The aim of this study was to provide an overview of evidence for improved outcomes by natural medicines. A systematic literature search was performed through Medline, PsycINFO, CINAHL, and Cochrane until May 2015. In 110 randomized controlled trials, evidence was found for glycine, sarcosine, N-acetylcysteine, some Chinese and ayurvedic herbs, ginkgo biloba, estradiol, and vitamin B6 to improve psychotic symptoms when added to antipsychotics. Ginkgo biloba and vitamin B6 seemed to reduce tardive dyskinesia and akathisia. Results on other compounds were negative or inconclusive. All natural agents, except reserpine, were well tolerated. Most study samples were small, study periods were generally short, and most results need replication. However, there is some evidence for beneficial effects of certain natural medicines.

N-acetylcysteine in a Double-Blind Randomized Placebo-Controlled Trial: Toward Biomarker-Guided Treatment in Early Psychosis

Biomarker-guided treatments are needed in psychiatry, and previous data suggest oxidative stress may be a target in schizophrenia. A previous add-on trial with the antioxidant N-acetylcysteine (NAC) led to negative symptom reductions in chronic patients. We aim to study NAC's impact on symptoms and neurocognition in early psychosis (EP) and to explore whether glutathione (GSH)/redox markers could represent valid biomarkers to guide treatment. In a double-blind, randomized, placebo-controlled trial in 63 EP patients, we assessed the effect of NAC supplementation (2700 mg/day, 6 months) on PANSS, neurocognition, and redox markers (brain GSH [GSHmPFC], blood cells GSH levels [GSHBC], GSH peroxidase activity [GPxBC]). No changes in negative or positive symptoms or functional outcome were observed with NAC, but significant improvements were found in favor of NAC on neurocognition (processing speed). NAC also led to increases of GSHmPFC by 23% (P = .005) and GSHBC by 19% (P = .05). In patients with high-baseline GPxBC compared to low-baseline GPxBC, subgroup explorations revealed a link between changes of positive symptoms and changes of redox status with NAC. In conclusion, NAC supplementation in a limited sample of EP patients did not improve negative symptoms, which were at modest baseline levels. However, NAC led to some neurocognitive improvements and an increase in brain GSH levels, indicating good target engagement. Blood GPx activity, a redox peripheral index associated with brain GSH levels, could help identify a subgroup of patients who improve their positive symptoms with NAC. Thus, future trials with antioxidants in EP should consider biomarker-guided treatment.

The effects of glycine on auditory mismatch negativity in schizophrenia

Glycine increases N-methyl-d-aspartate receptor (NMDAR) mediated glutamatergic function. Mismatch negativity (MMN) is a proposed biomarker of glutamate-induced improvements in clinical symptoms, however, the effect of glycine-mediated NMDAR activation on MMN in schizophrenia is not well understood. This study aimed to determine the effects of acute and 6-week chronic glycine administration on MMN in schizophrenia patients. MMN amplitude was compared at baseline between 22 patients (schizophrenia or schizoaffective disorder; receiving stable antipsychotic medication; multi-centre recruitment) and 21 age- and gender-matched controls. Patients underwent a randomised, double-blind, placebo-controlled clinical trial with glycine added to their regular antipsychotic medication (placebo, n=10; glycine, n=12). MMN was reassessed post-45-minutes of first dose (0.2g/kg) and post-6-weeks treatment (incremented to 0.6g/kg/day). Clinical symptoms were assessed at baseline and post-6-weeks treatment. At baseline, duration MMN was smaller in schizophrenia compared to controls. Acute glycine increased duration MMN (compared to placebo), whilst this difference was absent post-6-weeks treatment. Six weeks of chronic glycine administration improved PANSS-Total, PANSS-Negative and PANSS-General symptoms compared to placebo. Smaller baseline duration MMN was associated with greater PANSS-Negative symptoms and predicted (at trend level) PANSS-Negative symptom improvement post-6-weeks glycine treatment (not placebo). These findings support the benefits of chronic glycine administration and demonstrate, for the first time, that acute glycine improves duration MMN in schizophrenia. This result, together with smaller baseline duration MMN predicting greater clinical treatment response, suggests the potential for duration MMN as a biomarker of glycine-induced improvements in negative symptoms in schizophrenia.

Impaired mismatch negativity to frequency deviants in individuals at ultra-high risk for psychosis, and preliminary evidence for further impairment with transition to psychosis

BACKGROUND

There is evidence to suggest that people with established psychotic disorders show impairments in the mismatch negativity induced by a frequency-deviant sound (fMMN), and that these impairments worsen with the deterioration of psychotic symptoms. This study aimed to test whether individuals at ultra-high risk (UHR) for psychosis show pre-morbid impairments in fMMN, and if so, whether fMMN continues to deteriorate with transition to psychosis.

METHOD

fMMN was recorded in a cohort of UHR individuals (n=42) and compared to healthy controls (n=29). Of the 27 UHR participants who returned for a second EEG session, six participants had transitioned to psychosis by 12-month follow-up (UHR-T) and were compared to the 21 participants who did not transition (UHR-NT).

RESULTS

fMMN amplitude was significantly reduced, relative to healthy controls, in the UHR cohort. Furthermore, UHR-T individuals showed a significant decrease in fMMN amplitude over the period from baseline to post-transition; this reduction was not observed in UHR-NT.

CONCLUSIONS

These results suggest that fMMN is abnormal in UHR individuals, as has repeatedly been found previously in people with established psychotic disorders. The finding that fMMN impairment worsens with transition to psychosis is consistent with the staging model of psychosis; however, caution must be taken in interpreting these findings, given the extremely small sample size of the UHR-T group.

Improvement in mismatch negativity generation during d-serine treatment in schizophrenia: Correlation with symptoms

BACKGROUND

Deficits in N-methyl-d-aspartate-type (NMDAR) function contribute to symptoms and cognitive dysfunction in schizophrenia. The efficacy of NMDAR agonists in the treatment of persistent symptoms of schizophrenia has been variable, potentially reflecting limitations in functional target engagement. We recently demonstrated significant improvement in auditory mismatch negativity (MMN) with once-weekly treatment with d-serine, a naturally occurring NMDAR glycine-site agonist. This study investigates effects of continuous (daily) NMDAR agonists in schizophrenia/schizoaffective disorder.

METHODS

Primary analysis was on MMN after double-blind crossover (60mg/kg/d, n=16, 6weeks) treatment with d-serine/placebo. Secondary measures included clinical symptoms, neurocognition, and the effects of open-label (30-120mg/kg/d, n=21) d-serine and bitopertin/placebo (10mg, n=29), a glycine transport inhibitor.

RESULTS

Double-blind d-serine treatment led to significant improvement in MMN frequency (p=0.001, d=2.3) generation and clinical symptoms (p=0.023, d=0.80). MMN frequency correlated significantly with change in symptoms (r=-0.63, p=0.002) following co-variation for treatment type. d-Serine treatment led to a significant, large effect size increase vs. placebo in evoked α-power in response to standards (p=0.036, d=0.81), appearing to normalize evoked α power relative to previous findings with controls. While similar results were seen with open-label d-serine, no significant effects of bitopertin were observed for symptoms or MMN.

CONCLUSIONS

These findings represent the first randomized double-blind placebo-controlled study with 60mg/kg d-serine in schizophrenia, and are consistent with meta-analyses showing significant effects of d-serine in schizophrenia. Results overall support suggest that MMN may have negative, as well as positive, predictive value in predicting efficacy of novel compounds.

CLINICAL TRIALS REGISTRATION

Clinicaltrials.gov: NCT00322023/NCT00817336 (d-serine); NCT01116830 (bitopertin).

Treatment in early psychosis with N-acetyl-cysteine for 6months improves low-level auditory processing: Pilot study

Sensory impairments constitute core dysfunctions in schizophrenia. In the auditory modality, impaired mismatch negativity (MMN) has been observed in chronic schizophrenia and may reflect N-methyl-d-aspartate (NMDA) hypo-function, consistent with models of schizophrenia based on oxidative stress. Moreover, a recent study demonstrated deficits in the N100 component of the auditory evoked potential (AEP) in early psychosis patients. Previous work has shown that add-on administration of the glutathione precursor N-acetyl-cysteine (NAC) improves the MMN and clinical symptoms in chronic schizophrenia. To date, it remains unknown whether NAC also improves general low-level auditory processing and if its efficacy would extend to early-phase psychosis. We addressed these issues with a randomized, double-blind study of a small sample (N=15) of early psychosis (EP) patients and 18 healthy controls from whom AEPs were recorded during an active, auditory oddball task. Patients were recorded twice: once prior to NAC/placebo administration and once after six months of treatment. The N100 component was significantly smaller in patients before NAC administration versus controls. Critically, NAC administration improved this AEP deficit. Source estimations revealed increased activity in the left temporo-parietal lobe in patients after NAC administration. Overall, the data from this pilot study, which call for replication in a larger sample, indicate that NAC improves low-level auditory processing in early psychosis.

Meta-analysis of mismatch negativity to simple versus complex deviants in schizophrenia

Mismatch negativity (MMN) deficits in schizophrenia (SCZ) have been studied extensively since the early 1990s, with the vast majority of studies using simple auditory oddball task deviants that vary in a single acoustic dimension such as pitch or duration. There has been a growing interest in using more complex deviants that violate more abstract rules to probe higher order cognitive deficits. It is still unclear how sensory processing deficits compare to and contribute to higher order cognitive dysfunction, which can be investigated with later attention-dependent auditory event-related potential (ERP) components such as a subcomponent of P300, P3b. In this meta-analysis, we compared MMN deficits in SCZ using simple deviants to more complex deviants. We also pooled studies that measured MMN and P3b in the same study sample and examined the relationship between MMN and P3b deficits within study samples. Our analysis reveals that, to date, studies using simple deviants demonstrate larger deficits than those using complex deviants, with effect sizes in the range of moderate to large. The difference in effect sizes between deviant types was reduced significantly when accounting for magnitude of MMN measured in healthy controls. P3b deficits, while large, were only modestly greater than MMN deficits (d=0.21). Taken together, our findings suggest that MMN to simple deviants may still be optimal as a biomarker for SCZ and that sensory processing dysfunction contributes significantly to MMN deficit and disease pathophysiology.

Adjunctive N-acetylcysteine in depression: exploration of interleukin-6, C-reactive protein and brain-derived neurotrophic factor

OBJECTIVE

This study aimed to explore effects of adjunctive N-acetylcysteine (NAC) treatment on inflammatory and neurogenesis markers in unipolar depression.

METHODS

We embarked on a 12-week clinical trial of NAC (2000 mg/day compared with placebo) as an adjunctive treatment for unipolar depression. A follow-up visit was conducted 4 weeks following the completion of treatment. We collected serum samples at baseline and the end of the treatment phase (week 12) to determine changes in interleukin-6 (IL6), C-reactive protein (CRP) and brain-derived neurotrophic factor (BDNF) following NAC treatment.

RESULTS

NAC treatment significantly improved depressive symptoms on the Montgomery-Asberg Depression Rating Scale (MADRS) over 16 weeks of the trial. Serum levels of IL6 were associated with reductions of MADRS scores independent of treatment response. However, we found no significant changes in IL6, CRP and BDNF levels following NAC treatment.

CONCLUSION

Overall, this suggests that our results failed to support the hypothesis that IL6, CRP and BDNF are directly involved in the therapeutic mechanism of NAC in depression. IL6 may be a useful marker for future exploration of treatment response.

The coupling of low-level auditory dysfunction and oxidative stress in psychosis patients

Patients diagnosed with schizophrenia often present with low-level sensory deficits. It is an open question whether there is a functional link between these deficits and the pathophysiology of the disease, e.g. oxidative stress and glutathione (GSH) metabolism dysregulation. Auditory evoked potentials (AEPs) were recorded from 21 psychosis disorder patients and 30 healthy controls performing an active, auditory oddball task. AEPs to standard sounds were analyzed within an electrical neuroimaging framework. A peripheral measure of participants' redox balance, the ratio of glutathione peroxidase and glutathione reductase activities (GPx/GR), was correlated with the AEP data. Patients displayed significantly decreased AEPs over the time window of the P50/N100 complex resulting from significantly weaker responses in the left temporo-parietal lobe. The GPx/GR ratio significantly correlated with patients' brain activity during the time window of the P50/N100 in the medial frontal lobe. We show for the first time a direct coupling between electrophysiological indices of AEPs and peripheral redox dysregulation in psychosis patients. This coupling is limited to stages of auditory processing that are impaired relative to healthy controls and suggests a link between biochemical and sensory dysfunction. The data highlight the potential of low-level sensory processing as a trait-marker of psychosis.

Towards a neurodynamical understanding of the prodrome in schizophrenia

The identification of biomarkers for the early diagnosis of schizophrenia that could inform novel treatment developments is an important objective of current research. This paper will summarize recent work that has investigated changes in oscillatory activity and event-related potentials with Electro/Magnetoencephalography (EEG/MEG) in participants at high-risk for the development of schizophrenia, highlighting disruptions in sensory and cognitive operations prior to the onset of the syndrome. Changes in EEG/MEG-data are consistent with evidence for alterations in Glutamatergic and GABAergic neurotransmission as disclosed by Magnetic Resonance Spectroscopy and brain stimulation, indicating changes in Excitation/Inhibition balance parameters prior to the onset of psychosis. Together these data emphasize the importance of research into neuronal dynamics as a crucial approach to establish functional relationships between impairments in neural circuits and emerging psychopathology that together could be fundamental for early intervention and the identification of novel treatments for emerging psychosis.