Which perspectives can endophenotypes and biological markers offer in the early recognition of schizophrenia?

Predicting the diagnosis of various mental disorders in a mixed cohort using blood-based multi-protein model: a machine learning approach

The lack of objective diagnostic methods for mental disorders challenges the reliability of diagnosis. The study aimed to develop an easily accessible and useable objective method for diagnosing major depressive disorder (MDD), schizophrenia (SZ), bipolar disorder (BPD), and panic disorder (PD) using serum multi-protein. Serum levels of brain-derived neurotrophic factor (BDNF), VGF (non-acronymic), bicaudal C homolog 1 (BICC1), C-reactive protein (CRP), and cortisol, which are generally recognized to be involved in different pathogenesis of various mental disorders, were measured in patients with MDD (n = 50), SZ (n = 50), BPD (n = 55), and PD along with 50 healthy controls (HC). Linear discriminant analysis (LDA) was employed to construct a multi-classification model to classify these mental disorders. Both leave-one-out cross-validation (LOOCV) and fivefold cross-validation were applied to validate the accuracy and stability of the LDA model. All five serum proteins were included in the LDA model, and it was found to display a high overall accuracy of 96.9% when classifying MDD, SZ, BPD, PD, and HC groups. Multi-classification accuracy of the LDA model for LOOCV and fivefold cross-validation (within-study replication) reached 96.9 and 96.5%, respectively, demonstrating the feasibility of the blood-based multi-protein LDA model for classifying common mental disorders in a mixed cohort. The results suggest that combining multiple proteins associated with different pathogeneses of mental disorders using LDA may be a novel and relatively objective method for classifying mental disorders. Clinicians should consider combining multiple serum proteins to diagnose mental disorders objectively.

Association of Transferrin Gene Polymorphism with Cognitive Deficits and Psychiatric Symptoms in Patients with Chronic Schizophrenia

A large amount of recent literature has focused on impaired iron homeostasis in the pathophysiology of schizophrenia. Specifically, microarray analysis has illustrated associations between the transferrin locus and schizophrenia. To elaborate on the effects of transferrin on schizophrenia and its psychiatric phenotypes, our study aimed to investigate whether transferrin gene polymorphism was correlated with cognitive deficits and clinical symptoms in schizophrenia. We recruited 564 patients with chronic schizophrenia and 422 healthy controls (HCs) in a Han Chinese population, collected phenotypic data, and genotyped the rs3811655 polymorphism of the transferrin gene. Our results showed that the rs3811655 polymorphism was related to cognitive performance in both patients and HCs, as well as negative symptoms in patients (all p < 0.05), and patients carrying at least one G-allele showed worsened cognition/severe negative symptoms (all p < 0.05). Further analyses also found that the rs3811655 polymorphism in combination with cognition may exert small but significant contributions to the negative (β = −0.10, t = −2.48, p < 0.05) or total psychiatric symptoms (β = −0.08, t = −1.92, p < 0.05) in patients. Our findings indicated that the rs3811655 polymorphism may be implicated in the cognitive deficits of schizophrenia and HCs as well as psychiatric symptoms in patients, which suggested the possible iron regulatory mechanism in the pathology of schizophrenia.

Use of cognitive event-related potentials in the management of psychiatric disorders: Towards an individual follow-up and multi-component clinical approach

Relapse prevention remains a major challenge in psychiatry, thus indicating that the established treatment methods combining psychotherapy with neuropharmacological interventions are not entirely effective. In recent years, several intervention strategies have been devised that are aimed at improving psychiatric treatment by providing a complementary set of add-on tools that can be used by clinicians to improve current patient assessment. Among these, cognitive event-related potentials (ERPs) have been indexed as valuable biomarkers of the pathophysiological mechanisms of various mental illnesses. However, despite decades of research, their clinical utility is still controversial and a matter of debate. In this opinion review, I present the main arguments supporting the use of cognitive ERPs in the management of psychiatric disorders, stressing why it is currently still not the case despite the vast number of ERP studies to date. I also propose a clinically-oriented suitable way in which this technique could - in my opinion - be effectively incorporated into individual patient care by promotion of the use of individual ERP test-retest sessions and the use of a multi-component approach.

Frontal brain activity in individuals at risk for schizophrenic psychosis and bipolar disorder during the emotional Stroop task - an fNIRS study

OBJECTIVES

The emotional Stroop effect is defined as increased reaction times to emotional stimuli compared to neutral ones. It has been often reported in the literature, on both behavioral and neurophysiological level. The goal of this study was to investigate the frontal brain activation in individuals at risk for schizophrenic psychosis and bipolar disorder during an emotional Stroop task. We expected to observe decreased activation in the at-risk individuals compared to the healthy controls.

METHODS

Individuals at high risk for psychosis (HR), at ultra-high risk for psychosis (UHR), at risk for bipolar disorder (BIP) and healthy controls (HC) performed an emotional Stroop task, which included positively, negatively and neutrally valenced words. Functional near-infrared spectroscopy (fNIRS) was used to measure levels of oxygenated hemoglobin (O2Hb) representing brain activity in the dorsolateral prefrontal and frontotemporal cortex.

RESULTS

Results showed significantly decreased levels of O2Hb in the right dorsolateral prefrontal cortex (DLPFC) in the HR and UHR groups compared to the HC, indicating lower activity. Even though the decrease was independent from the valence of the words, it was the most visible for the negative ones. Moreover, significantly lower O2Hb levels in the frontotemporal cortex (FTC) were observed in all at risk groups compared to the HC.

CONCLUSIONS

Lower activity in the FTC in groups at risk for psychosis and bipolar disorder reflects unspecific dysfunctions. Decreased activity in the DLPFC in the HR and UHR groups indicates that hypofrontality can be found already in individuals at risk for schizophrenic psychosis.

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.

Combined serum levels of multiple proteins in tPA-BDNF pathway may aid the diagnosis of five mental disorders

Mental disorders are severe, disabling conditions with unknown etiology and are commonly misdiagnosed when clinical symptomology criteria are solely used. Our previous work indicated that combination of serum levels of multiple proteins in tissue plasminogen activator (tPA)-brain-derived neurotrophic factor (BDNF) pathway improved accuracy of diagnosis of major depressive disorder (MDD). Here, we measured serum levels of tPA, plasminogen activator inhibitor-1 (PAI-1), BDNF, precursor-BDNF (proBDNF), tropomyosin-related kinase B (TrkB) and neurotrophin receptor p75 (p75NTR) in patients with paranoid schizophrenia (SZ, n = 34), MDD (n = 30), bipolar mania (BM, n = 30), bipolar depression (BD, n = 22), panic disorder (PD, n = 30), and healthy controls (HCs, n = 30) by Enzyme-linked immunosorbent assay kits. We used receiver operating characteristic (ROC) curve to analyze diagnostic potential of these proteins. We found, compared with HCs, that serum tPA and proBDNF were lower in SZ, BM and BD; TrkB was lower in SZ and BD; and p75NTR was declined in SZ and BM. ROC analysis showed that combined serum level of tPA, PAI-1, BDNF, proBDNF, TrkB and p75NTR was better than any single protein in accuracy of diagnosis and differentiation, suggesting that the combination of multiple serum proteins levels in tPA-BDNF pathway may have a potential for a diagnostic panel in mental disorders.

Forecasting psychosis by event-related potentials-systematic review and specific meta-analysis

BACKGROUND

Prediction and prevention of psychosis have become major research topics. Clinical approaches warrant objective biological parameters to enhance validity in prediction of psychosis onset. In this regard, event-related potentials (ERPs) have been identified as promising tools for improving psychosis prediction.

METHODS

Herein, the focus is on sensory gating, mismatch negativity (MMN) and P300, thereby discussing which parameters allow for a timely and valid detection of future converters to psychosis. In a first step, we systematically reviewed the studies that resulted from a search of the MEDLINE database. In a second step, we performed a meta-analysis of those investigations reporting transitions that statistically compared ERPs in converting versus nonconverting subjects.

RESULTS

Sensory gating, MMN, and P300 have been demonstrated to be impaired in subjects clinically at risk of developing a psychotic disorder. In the meta-analysis, duration MMN achieved the highest effect size measures.

CONCLUSIONS

In summary, MMN studies have produced the most convincing results until now, including independent replication of the predictive validity. However, a synopsis of the literature revealed a relative paucity of ERP studies addressing the psychosis risk state. Considering the high clinical relevance of valid psychosis prediction, future research should question for the most informative paradigms and should allow for meta-analytic evaluation with regard to specificity and sensitivity of the most appropriate parameters.

Fetal programming of schizophrenia: select mechanisms

Mounting evidence indicates that schizophrenia is associated with adverse intrauterine experiences. An adverse or suboptimal fetal environment can cause irreversible changes in brain that can subsequently exert long-lasting effects through resetting a diverse array of biological systems including endocrine, immune and nervous. It is evident from animal and imaging studies that subtle variations in the intrauterine environment can cause recognizable differences in brain structure and cognitive functions in the offspring. A wide variety of environmental factors may play a role in precipitating the emergent developmental dysregulation and the consequent evolution of psychiatric traits in early adulthood by inducing inflammatory, oxidative and nitrosative stress (IO&NS) pathways, mitochondrial dysfunction, apoptosis, and epigenetic dysregulation. However, the precise mechanisms behind such relationships and the specificity of the risk factors for schizophrenia remain exploratory. Considering the paucity of knowledge on fetal programming of schizophrenia, it is timely to consolidate the recent advances in the field and put forward an integrated overview of the mechanisms associated with fetal origin of schizophrenia.

Schizophrenia as a self-disorder due to perceptual incoherence

The aim of this review is to describe the potential relationship between multisensory disintegration and self-disorders in schizophrenia spectrum disorders. Sensory processing impairments affecting multisensory integration have been demonstrated in schizophrenia. From a developmental perspective multisensory integration is considered to be crucial for normal self-experience. An impairment of multisensory integration is called 'perceptual incoherence'. We theorize that perceptual incoherence may evoke incoherent self-experiences including depersonalization, ambivalence, diminished sense of agency, and 'loosening of associations' between thoughts, feelings and actions that lie within the framework of 'self-disorders' as described by Sass and Parnas (2003). We postulate that subconscious attempts to restore perceptual coherence may induce hallucinations and delusions. Increased insight into mechanisms underlying 'self-disorders' may enhance our understanding of schizophrenia, improve recognition of early psychosis, and extend the range of therapeutic possibilities.

Neurological soft signs in non-psychotic patients with cannabis dependence

Psychomotor performance has consistently been found to be altered in chronic cannabis users. Neurological soft signs (NSS) reflect neurological dysfunction involving integrative networks, especially those involving the cerebellum, where cannabinoid receptors are particularly concentrated. Our objective was to study, for the first time, NSS in a group of patients with cannabis dependence compared with a of healthy control subjects, matched for age, gender and level of education. All outpatients seeking treatment for chronic cannabis use in the substance abuse department of Sainte-Anne Hospital in Paris between June 2007 and May 2009 and meeting the cannabis dependence DSM-IV criteria were included in the study (n = 45). Patients with psychotic disorders, bipolar 1 disorder and current alcohol, opioid or cocaine dependence were excluded. All patients and controls were assessed using the Diagnostic Interview for Genetic Studies, which screens for lifetime DSM-IV diagnoses, and the Standardized Neurological Examination of Neurological Soft Signs. NSS scores were significantly higher in patients with cannabis dependence compared with healthy subjects (8.90 ± 4.85 versus 6.71 ± 2.73, respectively, Mann-Whitney: U = 775.0, P = 0.05). Patients had particularly high scores on motor coordination and sensory integration NSS factors. Cannabis dependence is associated with more NSS and especially motor coordination and sensory integration signs. These results suggest that cannabinoids interact with the brain networks underlying NSS, known to be altered in schizophrenia.

Longitudinal study of neurological soft signs in first-episode early-onset psychosis

BACKGROUND

In recent decades, the assessment of neurological soft signs (NSS) in patients with psychosis has become a subject of special interest. The study of the progression of NSS during adolescence will provide valuable information about the role of NSS as endophenotypes or biomarkers and about brain development at a stage in which brain maturation has not yet been completed.

METHODS

Neurological soft signs were assessed in a sample of 110 first episodes of early-onset psychosis (EOP) and 98 healthy children and adolescents at two different times in a 2-year follow-up period.

RESULTS

Patients with EOP showed more NSS than controls both at baseline (p < .001) and the 2-year follow-up (p < .001). No differences were found in the number of signs among the different diagnostic subgroups (schizophrenia, bipolar disorder, and other psychoses). When we examined the changes in NSS over the follow-up, the reduction of NSS in the patients was greater than the controls for 'Motor coordination' (p = .032), 'Others' (p < .001), and 'Total score' (p < .001) of the NES.

CONCLUSION

Despite the greater reduction of NSS in patients than in controls along the follow-up, patients still have more neurological signs than healthy controls; therefore, these signs may be considered a trait marker. NSS do not seem to be specific to schizophrenia as they are present in different EOPs.

Adolescent attention deficit hyperactivity disorder and susceptibility to psychosis in adulthood: a review of the literature and a phenomenological case report

AIM

In contrast to affective disorders, some forms of personality disorders and drug addiction, schizophrenia is commonly not considered to be a sequela of attention deficit hyperactivity disorder. However, attention deficit hyperactivity disorder and the prodromal stages of schizophrenia spectrum disorders do exhibit a number of common central features. To facilitate the early treatment of schizophrenic symptoms, the detection of discrete and subtle alterations in the prodromal stages of incipient psychoses is particularly important.

METHODS

We review the literature on the prodromal symptoms of psychosis and present a case report, in which a phenomenological approach was used to identify subtle alterations linked to anomalous self-experience.

RESULTS

Using the Examination of Anomalous Self-Experience symptom checklist, the case report presented here reveals attention deficit hyperactivity disorder symptoms in adolescence as a precursor state of psychosis in adulthood.

CONCLUSIONS

The characteristics of this schizophrenia spectrum disorder case and its time course are derived from the specific distribution pattern of Examination of Anomalous Self-Experience items. When treating adolescent attention deficit hyperactivity disorder patients, the rare possibility of the development of schizophrenia spectrum disorder from attention deficit hyperactivity disorder like symptoms should be kept in mind.

A systematic review and meta-analysis of neurological soft signs in relatives of people with schizophrenia

BACKGROUND

Neurological soft signs are subtle but observable impairments in motor and sensory functions that are not localized to a specific area of the brain. Neurological soft signs are common in schizophrenia. It has been established that soft signs meet two of five criteria for an endophenotype, namely: association with the illness, and state independence. This review investigated whether soft signs met a further criterion for an endophenotype, namely familial association. It was hypothesized that if familial association were present then neurological soft signs would be: (a) more common in first-degree relatives of people with schizophrenia than in controls; and (b) more common in people with schizophrenia than in their first-degree relatives.

METHOD

A systematic search identified potentially eligible studies in the EMBASE (1980-2011), OVID - MEDLINE (1950-2011) and PsycINFO (1806-2011) databases. Studies were included if they carried out a three-way comparison of levels of soft signs between people with schizophrenia, their first-degree relatives, and normal controls. Data were extracted independently by two reviewers and cross-checked by double entry.

RESULTS

After screening 8678 abstracts, seven studies with 1553 participants were identified. Neurological soft signs were significantly more common in first-degree relatives of people with schizophrenia than in controls (pooled standardised mean difference (SMD) 1.24, 95% confidence interval (c.i) 0.59-1.89). Neurological soft signs were also significantly more common in people with schizophrenia than in their first-degree relatives (SMD 0.92, 95% c.i 0.64-1.20). Sensitivity analyses examining the effects of age and group blinding did not significantly alter the main findings.

CONCLUSIONS

Both hypotheses were confirmed, suggesting that the distribution of neurological soft signs in people with schizophrenia and their first-degree relatives is consistent with the endophenotype criterion of familial association.

Transition to adulthood: the critical period for pre-emptive, disease-modifying care for schizophrenia and related disorders

There is an urgent need and a global opportunity to rethink not only the dominant research paradigms in etiological research but also to invest in less constrained strategies which cut across the existing diagnostic silos to seek out common risk factors, late as well as early neurodevelopmental processes, pathophysiologies, and novel treatment strategies. The high-quality research presented in this special issue of Schizophrenia Bulletin makes a compelling case for such a rethink. While there is still a genuine disconnect between our understanding of the complex and dramatic brain changes that occur during the transition to adulthood and the concurrent surge in incidence of mental ill-health, there is no doubt that a much more serious focus on the perionset stage of clinical disorders in young people with their rapidly evolving brains, social environments, and life trajectories could be extremely productive. Research access to these early stages of illness would be catalyzed by the widespread construction of engaging stigma-free portals and clinical scaffolding appropriate for young people in the 21st century. The latter are urgently required to supersede traditional models of care, which have served both patients and families so poorly, and equally have failed to unlock a deeper understanding of the origins and progression of potentially serious mental disorders.

Premorbid cognitive deficits in young relatives of schizophrenia patients

Neurocognitive deficits in schizophrenia (SZ) are thought to be stable trait markers that predate the illness and manifest in relatives of patients. Adolescence is the age of maximum vulnerability to the onset of SZ and may be an opportune "window" to observe neurocognitive impairments close to but prior to the onset of psychosis. We reviewed the extant studies assessing neurocognitive deficits in young relatives at high risk (HR) for SZ and their relation to brain structural alterations. We also provide some additional data pertaining to the relation of these deficits to psychopathology and brain structural alterations from the Pittsburgh Risk Evaluation Program (PREP). Cognitive deficits are noted in the HR population, which are more severe in first-degree relatives compared to second-degree relatives and primarily involve psychomotor speed, memory, attention, reasoning, and social-cognition. Reduced general intelligence is also noted, although its relationship to these specific domains is underexplored. Premorbid cognitive deficits may be related to brain structural and functional abnormalities, underlining the neurobiological basis of this illness. Cognitive impairments might predict later emergence of psychopathology in at-risk subjects and may be targets of early remediation and preventive strategies. Although evidence for neurocognitive deficits in young relatives abounds, further studies on their structural underpinnings and on their candidate status as endophenotypes are needed.

Neuroimaging in psychiatry: from bench to bedside

This perspective considers the present and the future role of different neuroimaging techniques in the field of psychiatry. After identifying shortcomings of the mainly symptom-focussed diagnostic processes and treatment decisions in modern psychiatry, we suggest topics where neuroimaging methods have the potential to help. These include better understanding of the pathophysiology, improved diagnoses, assistance in therapeutic decisions and the supervision of treatment success by direct assessment of improvement in disease-related brain functions. These different questions are illustrated by examples from neuroimaging studies, with a focus on severe mental and neuropsychiatric illnesses such as schizophrenia and depression. Despite all reservations addressed in the article, we are optimistic that neuroimaging has a huge potential with regard to the above-mentioned questions. We expect that neuroimaging will play an increasing role in the future refinement of the diagnostic process and aid in the development of new therapies in the field of psychiatry.

Schizophrenia genomics and proteomics: are we any closer to biomarker discovery?

The field of proteomics has made leaps and bounds in the last 10 years particularly in the fields of oncology and cardiovascular medicine. In comparison, neuroproteomics is still playing catch up mainly due to the relative complexity of neurological disorders. Schizophrenia is one such disorder, believed to be the results of multiple factors both genetic and environmental. Affecting over 2 million people in the US alone, it has become a major clinical and public health concern worldwide. This paper gives an update of schizophrenia biomarker research as reviewed by Lakhan in 2006 and gives us a rundown of the progress made during the last two years. Several studies demonstrate the potential of cerebrospinal fluid as a source of neuro-specific biomarkers. Genetic association studies are making headway in identifying candidate genes for schizophrenia. In addition, metabonomics, bioinformatics, and neuroimaging techniques are aiming to complete the picture by filling in knowledge gaps. International cooperation in the form of genomics and protein databases and brain banks is facilitating research efforts. While none of the recent developments described here in qualifies as biomarker discovery, many are likely to be stepping stones towards that goal.

Früherkennung und Frühbehandlung der Schizophrenie: Chance oder Dilemma?

Zusammenfassung: Die Früherkennung und Frühbehandlung von Psychosen aus dem schizophrenen Formenkreis bei Kinder- und Jugendlichen gilt als wichtiges therapeutisches Ziel, da ein Zusammenhang zwischen verzögertem Behandlungsbeginn und ungünstigem Gesamtverlauf immer wieder postuliert wurde. Die Dauer der unbehandelten Psychose (DUP) ist bei Jugendlichen gegenüber Erwachsenen signifikant verlängert, was sowohl mit einem schleichenden Beginn der Symptomatik als auch mit möglicher Bagatellisierung durch Familien und Helfersysteme in Verbindung gebracht wird. Kritisch wird die Idee der Primärprävention beleuchtet, da die Vorfeldsymptomatik des Prodroms auf Grund ihrer Unspezifität eine schizophreniespezifische Intervention nicht möglich macht. Überlegungen zum Vulnerabilitätsmodell der Pathogenese und zukünftige Frühdiagnosestrategien einer mehrdimensionalen biopsychosozialen Risikoabschätzung werden vorgestellt.