Psychogenic non-epileptic seizures: Chronology of multidisciplinary team approach to diagnosis and management

While the diagnosis and management of psychogenic non-epileptic seizures (PNES) remain challenging, certain evidence-based guidelines exist, which can help to optimize patient care. A multidisciplinary team approach appears to have many benefits. Current recommendations exist for some aspects of diagnosis and management of PNES, including levels of diagnostic certainty as proposed by the International League Against Epilepsy's expert Task Force on PNES. Other aspects of clinical still care lack clear consensus, including use of suggestion techniques for recording PNES and optimal terminology, since the term "functional seizures" has recently been proposed as a possible term to replace "PNES". The present article aims to (1) review current recommendations and (2) discuss our own team's experience in managing patients with PNES. This is organized chronologically in terms of the roles of the neurologist, psychiatrist and psychologist, and discusses diagnostic issues, psychiatric assessment and treatment, and psychotherapeutic approaches.

Depressive symptoms and chronic peripheral inflammation are associated with impaired functional remission in schizophrenia independently of psychotic remission

BACKGROUND

While psychotic remission in schizophrenia (SZ) has been defined by consensus and associated with a rank of clinical predictive factors, there is a lack of data of factors associated with functional remission.

OBJECTIVES

To identify clinical and biological factors associated with impaired functional remission in a non-selected chronic stabilized SZ outpatients.

METHODS

This study was a cross-sectional study carried out on all admitted SZ stabilized outpatients in an academic daily care psychiatric hospital. Functional remission was defined by a global assessment of functioning score ≥61. Psychotic remission was defined according to international criteria. Depression was assessed with the Calgary Depression Rating scale for Schizophrenia. Sociodemographic variables, tobacco status, clozapine treatment and obesity were reported. Chronic peripheral inflammation was defined by a highly sensitive C-reactive protein serum level ≥3 mg/L and metabolic syndrome according to international recommendations.

RESULTS

273 patients were included, among them 51 (18.7%) were classified in the functional remission group. In the multivariate analysis, higher rate of functional remission was associated with psychotic remission (adjusted Odd ratio = 18.2, p <0.001), lower depressive symptoms (aOR=0.8, p = 0.018) and lower peripheral inflammation (aOR=0.4, p = 0.046). No association of functional remission with age, gender, illness duration, second-generation antipsychotics, clozapine treatment, tobacco smoking, obesity or metabolic syndrome has been found.

CONCLUSION

Depressive symptoms and chronic peripheral inflammation are associated with impaired functional remission in SZ independently of psychotic remission. Future intervention studies should determine if improving depressive symptoms and chronic peripheral inflammation may improve SZ patients reaching functional remission.

Quality of life is associated with chronic inflammation in depression: A cross-sectional study

BACKGROUND

Inflammation may play a crucial role in the pathophysiology of depression. However, the association between chronic inflammation and health outcomes in depression remains unclear, particularly for patient-reported outcomes.

METHODS

The aim of this study was to investigate the relationship between quality of life (QoL) (physical and mental health, assessed by the SF-36) and chronic inflammation assessed using C-reactive protein (CRP) in patients with current major depressive disorder.

RESULTS

One hundred eighty-one patients with depression were enrolled in this study. After adjusting for key socio-demographic, clinical and biological confounding factors, patients with high levels of CRP (> 3.0mg/L) had worse physical health than those with normal CRP levels (OR = 0.95, 95% CI = 0.92-0.99). Significant associations were found between a higher rate of metabolic syndrome (OR = 0.10, 95% CI = 0.02-0.41) and high CRP levels.

LIMITATIONS

The cut-off point for high cardiovascular risk was used to define the two groups: normal CRP level and high CRP level. CRP was the sole marker of inflammation in this study and was collected at only one time point. The design of this study is cross-sectional and there are no conclusions about the directionality of the association between QoL and inflammation in depression. QoL was assessed only by SF-36 scores.

CONCLUSION

This study found an association between SF-36 physical health score and CRP in patients with depression, thereby showing the need to consider physical well-being in depression. This paves the way for interventions to act both on inflammation and QoL in patients with depression.

High C-reactive protein levels are associated with depressive symptoms in schizophrenia

BACKGROUND

Depressive symptoms are frequently associated with schizophrenia symptoms. C - Reactive protein (CRP), a marker of chronic inflammation, had been found elevated in patients with schizophrenia and in patients with depressive symptoms. However, the association between CRP level and depressive symptoms has been poorly investigated in patients with schizophrenia. The only study conducted found an association between high CRP levels and antidepressant consumption, but not with depressive symptoms investigated with the Calgary Depression Rating Scale for Schizophrenia (CDSS).

OBJECTIVES

The aim of this study was to evaluate CRP levels and depressive symptoms in patients with schizophrenia, and to determine whether high CRP levels are associated with depressive symptoms and/or antidepressant consumption, independently of potential confounding factors, especially tobacco-smoking and metabolic syndrome.

METHODS

Three hundred and seven patients with schizophrenia were enrolled in this study (mean age = 35.74 years, 69.1% male gender). Depressive symptoms was investigated with the CDSS. Patients were classified in two groups: normal CRP level (≤ 3.0mg/L) and high CRP level (> 3.0mg/L). Current medication was recorded.

RESULTS

124 subjects (40.4%) were classified in the high CRP level group. After adjusting for confounding factors, these patients were found to have higher CDSS scores than those with normal CRP levels in multivariate analyses (p = 0.035, OR = 1.067, 95% CI = 1.004-1.132). No significant association between CRP levels and antidepressants consumption was found.

LIMITATIONS

The size sample is relatively small. The cut-off point for high cardiovascular risk was used to define the two groups. CRP was the sole marker of inflammation in this study and was collected at only one time point. The design of this study is cross-sectional and there are no conclusions about the directionality of the association between depression and inflammation in schizophrenia.

CONCLUSION

This study found an association between high rates of CRP levels and depressive symptoms in patients with schizophrenia, but no association with antidepressant consumption. Further studies are needed to investigate the impact of inflammation in schizophrenia.

[What place for placebo in clinical trials conducted on psychiatric patients?]

Placebo effect remains a crucial issue in current clinical trials. Most clinical trials rely on the hypothesis of equivalent placebo response rates in both placebo and specific drug arms ("additive model"). But contrary to this dominant and rarely questioned hypothesis, several aspects may influence placebo response. A few recent meta-analyses and reviews have shown evidence for several clinical and methodological factors, which are able to modulate placebo response. In psychiatry research, placebo response has been mainly explored through antidepressant trials. In early clinical trials, drug-placebo differences were initially significant and robust. However, more recent clinical trials have not yielded similar results, and rather show narrowed antidepressant-placebo differences. Several factors may be involved in this absence of comparability: intrinsic properties of new antidepressants, changes in clinical criteria and classifications, symptomatic remission rather than global remission criteria, industrial and institutional constraints. Moreover, results from antidepressant trials (laboratory conditions) remain hardly fully transposable to clinical routine (ecological conditions).

On the correlation between perceptual inundation caused by realistic immersive environmental auditory scenes and the sensory gating inventory in schizophrenia

BACKGROUND

In schizophrenia, perceptual inundation related to sensory gating deficit can be evaluated "off-line" with the sensory gating inventory (SGI) and "on-line" during listening tests. However, no study investigated the relation between "off-line evaluation" and "on-line evaluation". The present study investigates this relationship.

METHODS

A sound corpus of 36 realistic environmental auditory scenes was obtained from a 3D immersive synthesizer. Twenty schizophrenic patients and twenty healthy subjects completed the SGI and evaluated the feeling of "inundation" from 1 ("null") to 5 ("maximum") for each auditory scene. Sensory gating deficit was evaluated in half of each population group with P50 suppression electrophysiological measure.

RESULTS

Evaluation of inundation during sound listening was significantly higher in schizophrenia (3.25) compared to the control group (2.40, P<.001). The evaluation of inundation during the listening test correlated significantly with the perceptual modulation (n=20, rho=.52, P=.029) and the over-inclusion dimensions (n=20, rho=.59, P=.01) of the SGI in schizophrenic patients and with the P50 suppression for the entire group of controls and patients who performed ERP recordings (n=20, rho=-.49, P=.027).

CONCLUSION

An evaluation of the external validity of the SGI was obtained through listening tests. The ability to control acoustic parameters of each of the realistic immersive environmental auditory scenes might in future research make it possible to identify acoustic triggers related to perceptual inundation in schizophrenia.

[Affective disorders: endocrine and metabolic comorbidities]

Links between affective and endocrine-metabolic disorders are numerous and complex. In this review, we explore most frequent endocrine-metabolic comorbidities. On the one hand, these comorbidities imply numerous iatrogenic effects from antipsychotics (metabolic side-effects) or from lithium (endocrine side-effects). On the other hand, these comorbidities are also associated with affective disorders independently from medication. We will successively examine metabolic syndrome, glycemic disturbances, obesity and thyroid disorders among patients with affective disorders. Endocrinemetabolic comorbidities can be individually encountered, but can also be associated. Therefore, they substantially impact morbidity and mortality by increasing cardiovascular risk factors. Two distinct approaches give an account of processes involved in these comorbidities: common environmental factors (iatrogenic effects, lifestyle), and/or shared physiological vulnerabilities. In conclusion, we provide a synthesis of important results and recommendations related to endocrine-metabolic comorbidities in affective disorders : heavy influence on morbidity and mortality, undertreatment of somatic diseases, importance of endocrine and metabolic side effects from main mood stabilizers, impact from sex and age on the prevalence of comorbidities, influence from previous depressive episodes in bipolar disorders, and relevance of systematic screening for subclinical (biological) disturbances.

[Mixed states and neuroimaging]

Despite the growing number of neuroimaging studies in bipolar disorder over the past years, the brain regions involved in mood dysregulation in this disease are still poorly understood. If some neurofunctional abnormalities seem to be independent of mood state, others were preferentially associated with mania or depression, involving the amygdala and other limbic regions as well as ventral frontal regions, with a likely hemispheric lateralization of these abnormalities according to the thymic state that was examined. Very few imaging studies became interested in bipolar patients in a mixed state, making it harder to connect brain malfunction to a given mood state. However, data obtained so far support the hypothesis of a lateralization of brain abnormalities in relation to bipolar symptomatology, suggesting that neurofonctional abnormalities preferentially located in the right ventral frontal and limbic areas may underlie the depressive component, associated with abnormalities of the left similar regions for the manic component. Identification of brain dysfunctions that may explain the emergence of mixed symptoms will likely provide useful information to better understand the respective roles of each hemisphere in the pathophysiology of bipolar disorder.

[Clinical description of mixed mania]

DSM-IV mixed states have become the mixed mania and mixed depression in the new DSM-5. One noticeable point is the introduction of nine cations, among which the "with mixed features" specification. These non exclusive specifications may contribute to a more precise identification of mixed clinical pictures, and therefore to offer a more efficient therapeutic answer. Different dimensional approaches are widely documented. They allow the isolation of a mixed factor which is clinically associated with two other specifications: anxious distress and psychotic features. These severity markers may encourage clinicians to be alert about the risk of misdiagnosis, and cautious in the management of these clinical situations.

[Neurocognitive fuctioning in pure mania and mixed mania]

Neurocognitive dysfunction is increasingly recognized as a prominent feature of bipolar disorder. Cognitive function seems to be impaired across different states of bipolar illness. Nervertheless, research that studies neuropsychological functioning in acute phases is scarce. Acutely ill patients have shown dysfunctions in several cognitive areas. We reviewed the literature on neuropsychological studies of acute phases to highlight neurocognitive deficits in mixed and pure mania. The results show dysfunctions in sustained attention that are significantly more important in mixed mania rather than in pure mania. Impulsive pattern of responding seems to characterize pure manic state. We also found impairments in processing speed, verbal and spatial learning/memory and executive functions, including cognitive flexibility, inhibitory control, conceptual reasoning, planning and problem solving. Disturbance in executive functioning seems to be more important in pure mania rather than mixed mania.

[Endophenotypes: the molecular biology point of view]

Endophenotypes are proposed for a better understanding of the molecular substrate underlying psychiatric disorders vulnerability. In this review, we discuss key points of the definition of endophenotypes from the molecular biology point of view. First, we examine the concept of heritability of endophenotype, which does not directly explain the molecular mechanisms responsible for the studied disorder Indeed, we discuss the necessity to better decipher the functional role of polymorphisms associated to endophenotypes, especially if those endophenotypes would be assigned a clinical and biological value. The complexity of endophenotypes definition and use in psychiatric research is also illustrated by the complexity of the human genome organization and gene networks as well as by the gene x environment interactions and also the possible existence of phenocopies.

[Neurophysiological endophenotypes and schizophrenic disorder: emergence and evolution of a clinical concept]

It is proposed an historical approach to concepts leading to the development of operational paradigms for measuring objectives neurophysiological endophenotypes. It is hypothesized that psychiatric interest for paradigms measuring Event-Related Potential (ERP) come from Bleuler (1911) and McGhie and Chapman (1961) phenomenological and clinical descriptions. They noted, first that patients with schizophrenia generally feel as if they are being flooded by an overwhelming mass of sensory input combined with a heightened sensory perception, second that they were distractible to irrelevant sensory stimuli. These subjective abnormalities may be related, first to inability to filter incongruent information measured in a double click paradigm by a deficit in P50 amplitude gating, and second to an inability to select a stimulus of interest measured in the oddball paradigm by a deficit in P300 amplitude. The analysis of these P50 and P300 ERP in cohorts of patients with schizophrenia found most of Gottesman endophenotype criteria. P50 and P300 ERP are therefore relevant neurophysiological endophenotypes. However, from a clinical point of view, these endophenotypes lack specificity. The hypothesis of this article leads us to formulate ways of research. It is shown the value of combining objective neurophysiological measures with subjective measures using self-administered questionnaires ("offline") or psychophysiological tests ("online") to develop rigorous neurophysiological experimental paradigms especially as clinical observations of their origins are not forgotten.

[Decision-making and schizophrenia]

Abnormalities involving the prefrontal cortex (PFC) have long been postulated to underpin the pathophysiology of schizophrenia. Investigations of PFC integrity have focused mainly on the dorsolateral PFC (DLPFC) and abnormalities in this region have been extensively documented. However, defects in schizophrenia may extend to other prefrontal regions, including the ventromedial PFC (VMPFC), and evidence of VMPFC abnormalities comes from neuropathological, structural and functional studies. Patients with acquired brain injury to the VMPFC display profound disruption of social behaviour and poor judgment in their personal lives. The Iowa Gambling Task (IGT) was developed to assess decision-making in these neurological cases : it presents a series of 100 choices from four card decks that differ in the distribution of rewarding and punishing outcomes. Whilst healthy volunteers gradually develop a preference for the two "safe" decks over the course of the task, patients with VMPFC lesions maintain a preference for the two "risky" decks which are associated with high reinforcement in the short term, but significant long-term debt. Interestingly, damage to VMPFC may cause both poor performance on the IGT and lack of insight concerning the acquired personality modification. Recently, our group reported a trait-related decisionmaking impairment in the three phases of bipolar disorder. In a PET study, VMPFC dysfunction was shown in bipolar manic patients impaired on a decision-making task and an association between decision-making cognition and lack of insight was described in mania. A quantitative association between grey matter volume of VMPFC and memory impairment was previously reported in schizophrenia. Research suggests that lack of insight is a prevalent feature in schizophrenia patients, like auditory hallucinations, paranoid or bizarre delusions, and disorganized speech and thinking. Because schizophrenia is associated with significant social or occupational dysfunction, previous research assessed decision-making function but indicates conflicting results. Thirteen studies have reported impaired IGT performance in patients with schizophrenia and, in seven reports, no significant differences in IGT performance between patient and healthy control groups were found. Those discrepancies may relate to multiple factors. First, most of the studies included small sample size and negative findings may be due to the large variance of net scores. Second, as suggested by Rodríguez-Sánchez et al., there is a wide disparity in performance by control subjects across studies. Third, intelligence quotient (IQ) score and level of education may be correlated with IGT performance, which may explain IGT performance differences in studies that did not control for educational or IQ score. Fourth, only two studies have systematically controlled for substance use disorder, a potential confounder. Fifth, only two studies assessed the impact of antipsychotic (AP) class on performance. Sixth, to our knowledge, no study assessed the impact of AP dosage on decision-making ability, while AP dose-reduction and dopamine increase, might lead to improvements, in cognitive functions in schizophrenia and in IGT performance in bipolar disorder, respectively. Finally, discrepancies between studies may be related to the heterogeneity of diagnostic groups. Two of the negative studies included schizophrenia and schizoaffective disorder while positive studies have generally included only patients with schizophrenia. Nevertheless, some studies that included only patients with schizophrenia failed to find differences between groups. Thus, further research should assess decision-making in schizophrenia by testing a large group of patients with homogeneity of diagnostic, in comparison with a large group of control subjects. Authors should control for IQ or level of education, substance use disorder and smoking status. While it is now accepted that DLPFC defects in schizophrenia may extend to VMPFC, future investigations should test for an association between memory, insight ability and IGT performance and assess the impact of antipsychotic dosage upon performance.

[Schizophrenia, psychotropic drugs and cognition]

The robust and specific associations between cognitive abilities and the functional prognosis of patients suffering from schizophrenia lead to a major concern for cognitive impairment in this disorder. Among the strategies considered to correct or enhance cognition in schizophrenia, drugs hold a pivotal place. Evidently, antipsychotic drugs, which are inextricable from patients' management, have generated considerable scrutiny in this topic. This paper first aims to outline the current views on the impact of antipsychotic drugs in schizophrenia. The distinction between conventional and atypical drugs is reminded in order to more precisely review existing data comparing the impact of these two types of molecules on cognitive impairment. More specifically, an elementary framework is proposed to facilitate the recognition of methodological flaws and offer a critical examination of previous findings. It emerges subsequently that differences between atypical and conventional drugs appear far less contrasted than initially suggested. Also, atypical antipsychotics compose a disparate pharmacological class and much clarification could be obtained by differentiating the individual effects of these molecules rather than considering them as a group. Finally, the relevance of these cognitive measures is also considered. In particular, we address alternative measures closer to real life situations as well as the growing interest in the broad field of social cognition. A last part of this article deals with strategies relying on adjunctive therapies. The fairly modest results obtained with these approaches is evoked and briefly reviewed.

[Schizophrenia, cognition and neuroimaging]

Schizophrenia is a complex illness whose mechanisms are still largely unknown. Functional brain imaging, by making the link between psyche and brain, has recently become an indispensable tool to study in vivo the neural bases underlying cognitive dysfunction in this disease. But despite the proliferation of data coming from this approach, the exact impact of functional imaging on our understanding of the disease remains blurry. In general, studies of the brain functioning of patients with schizophrenia found activation abnormalities which vary in nature and localization depending of the cognitive paradigm used. However, it appears that neurofunctional abnormalities observed in patients cannot be reduced to a simple well-localized deficit. It would be rather an alteration of the dynamics of the interactions between different brain regions that underlie the cognitive disturbances encountered in the disease. Functional brain imaging now offers new perspectives to clarify the dynamics of the brain networks, and particularly those involved in high-level cognitive functions, such as cognitive control or social cognition which seem to play a crucial role in the disease. The characterization of these features is an important issue not only to develop new hypotheses on the pathophysiology of the disorder, but also more pragmatically to identify potential therapeutic targets.

[Interpersonal sensorimotor coordination dynamics in schizophrenic patients: introducing a new experimental paradigm]

Compared to healthy individuals, schizophrenic patients suffer from sensorimotor disorders including problems when tracking moving targets and perceiving biological motion. Recent advances in embodied cognition and social coordination dynamics have emphasized the important role played by bodily information exchange (e.g. facial expressions, posture, and movements) in the way people interact with and mutually influence each other. These experimental studies on healthy participants provide data on sensorimotor performances of a patient that are recorded at high temporal and spatial resolutions. They should therefore be considered in studies on schizophrenic patients. These functional, quantitive and dynamic aspects of sensorimotor coordination abilities, may offer promising perspectives and could lead to a better understanding of sensorimotor disorders in schizophrenia. The purpose of this article is to introduce a new experimental paradigm in schizophrenia inspired by the field of coordination dynamics, a theoretical and experimental approach born more than 30 years ago that has recently expanded to interpersonal interactions, the so-called social coordination dynamics. In our study, we hypothesize that the sensorimotor deficits associated with schizophrenia in social interaction may be, at least partially, due to a failure to properly pick up information about the movements of other people. We therefore designed a study where healthy individuals and schizophrenic patients were asked to intentionally track the oscillations of visual targets of various social relevance using hand movements. Four different rhythmic visual stimuli varying in degree of biological relevance (form and motion) are used: [1] an oscillating dot; [2] a computer generated hand moving up and down continuously driven by a sine function; [3] pre-recorded oscillatory movements of a real hand; and [4] the hand of a real individual (behind a curtain that occluded vision of the rest of the body). Two distinct dependent variables are computed to quantify the coordination between the movements of the participants and the visual stimuli: the relative phase and the power spectrum overlap between their own movements. In this preliminary study, analyses of kinematic data revealed that schizophrenic patients had trouble synchronizing to (the more) "biological" target unlike control healthy individuals. These results suggest that patients with schizophrenia may suffer from sensorimotor coordination disabilities with socially relevant visual stimuli. The novel paradigm we introduce in research on schizophrenia should allow for a better understanding of the troubles these patients encounter when interacting with other people thanks to an approach rooted and building on social coordination dynamics as well as motor and social cognition.

[Schizophrenia, cognition and psychoeducation]

Cognitive impairment among patients suffering from schizophrenia is closely linked to psychoeducation and therapeutic education. First, this cognitive impairment requires specific communication strategy and special cognitive and behavioral techniques, which make possible for the patients to improve their trainability. Some of these tools are detailed, such as solving problems, communication skills, role plays, repetition, rewarding, and motivational support. Second, functional and social impairment, and outcome, are partly consequences of these cognitive problems. Cognitive remediation targets elementary cognitive impairment, mostly with repetitive cognitive tasks, and studies show an improvement in these specific tasks, but without positive effect on functional and social aspects of the illness. Overall approaches, such as psychoeducation or therapeutic education, obtain real gains in quality of life for the patients, autonomy and clinical improvement. It's not yet possible to know if these positive results underlie improvement in elementary cognitive impairment. The combination between remediation and psychoeducation seems to be promising.

[Towards a new approach of neurophysiology in clinical psychiatry: functional magnetic resonance imaging neurofeedback applied to emotional dysfunctions]

Emotions color in a singular way our everyday life and constitute important determinants of human cognition and behavior. Emotional regulation is an essential process involved in neuropathophysiology and therapeutic efficacy in many psychiatric disorders. Yet, traditional psychiatric therapeutic has focused on symptomatic rather than neurophysiological criteria. Therefore, it was proposed to teach patients to modify their own brain activity directly, in order to obtain a therapeutic effect. These techniques, which are named neurofeedback, were originally developed using electroencephalography. Recent technical advances in fMRI enable real-time acquisition, and open opportunities to its utilization in neurofeedback. This seems particularly interesting in emotion regulation, which, at a neurofunctional level, lies on cortico-limbic pathways that, in great parts, were previously identified by traditional fMRI paradigms. This emotion regulation plays a central role in the etiopathogeny psychiatric, especially depressive and anxious, disorders. It is possible to devise new therapeutic strategies and research approach for addressing directly the neurophysiological processes of emotion regulation by integrating the neurofunctional activities of a subject. These prospects seem to be in line with the neurophenomenology project, which proposes to establish a link between subjective experiences and objective neurophysiological measures.

[Theory of mind and schizophrenia]

In social cognition, the notion of Theory of Mind (ToM) is widely studied among people with schizophrenia to give an account for intersubjective disturbances. ToM is classically defined as the ability to make inferences about other persons'mental states, as beliefs, thoughts or intentions. However, ToM is not understood or explored as a homogeneous notion. First, this review briefly describes main theoretical models, as well as experimental tasks of ToM. Second, clinical results strongly suggest that patients with schizophrenia present impaired ToM performances. However, the presence of a robust relationship between ToM and schizophrenic symptomatology, or clinical course, is still controversial. Third, we highlight main findings from functional brain imaging studies based on ToM. Finally and in a more critical perspective, we suggest a few theoretical and experimental limitations regarding impaired ToM as a core feature of schizophrenic disturbances in social interactions.

[Schizophrenia, genetics and cognition]

Schizophrenia is a complex and heritable disorder. Nevertheless, molecular genetics of schizophrenia remains inconclusive. By developing the concept of endophenotype for the disorder, it is easier to define an association between a phenotype and genetic variants or physiopathological processes. Cognitive disorders could be useful endophenotypes for schizophrenia. For example, the val(158)/met COMT polymorphism has been associated with executive function or working memory. Therefore, several cognitive dysfunctions were proposed as endophenotypes and were investigated in the context of different genetic polymorphisms. Genome-wide association studies and epistatic studies demonstrated the complexity of the mechanisms underlying cognitive disturbance. However, meta-analysis remains inconclusive. Altogether, the study of endophenotypes is an attractive approach to solve the complex mechanisms causing schizophrenia vulnerability. Nevertheless, several limitations exist and include the lack of reproducibility, the discordant results between healthy subjects and patients, the exclusion of the many rare variants.

[Electrophysiology and schizophrenic vulnerability: the P300 component as endophenotype candidate?]

INTRODUCTION

Studies on early stages of schizophrenia imply the observation of stable markers of vulnerability. Among other research fields, these early and objective markers, or potential endophenotypes, can be described in event-related potential (ERP) paradigms.

LITERATURE FINDINGS

The P300 component, elicited during the allocation of attentional resources, is the most studied ERP among people with schizophrenia. In this review, we first develop the notion of endophenotypes in schizophrenia, notably in terms of stability, heritability and specificity. We also give a short account of the P300 component, its typical description, the classical paradigms which elicit it, and several interpretations of its significance.

DISCUSSION

After reviewing the main features of the schizophrenic alterations of P300 (their topography, amplitude and latency), we discuss the relevance of P300 when described as a potential schizophrenic endophenotype. In spite of an important number of studies, results remain controversial and incomplete. First, P300 in schizophrenia shows complex patterns of temporal evolution, and thus can be described as either a stable trait or a state marker. Second, its heritability is still discussed among high-risk participants with genetic, schizotypal or clinical vulnerability. Third, the issue of its specificity is the less studied criteria. In line with the debate of its specificity, only little is known about specific alterations of P300 among unipolar or bipolar disorders. In the discussion, we describe a few possible origins of such controversial results in both empirical and conceptual perspectives, and we provide several experimental propositions in order to develop a more systematic exploration of P300 alterations.

What is bizarre in bizarre delusions? A critical review

Diagnostic and Statistical Manual of Mental Disorder, Fourth Edition (DSM-IV) treats the presence of bizarre delusions (BD) as the heaviest-weighted clinical criterion of schizophrenia. Although BD play a major role in contemporary diagnostic systems, only a few empirical studies explore this issue. These studies provide highly heterogenous results because they are based on different experimental paradigms, in terms of definition, clinical sample, and number of raters. Here, we first discuss the psychopathological sources of the concept of BD, which were initially described as either nonsensical or incomprehensible. Then, we provide a critical review of contemporary studies on the reliability of BD and their methodological and conceptual limitations. Current approaches have focused intensely on BD's reliability and have defined BD strictly in terms of delusional content--mainly in terms of the physical impossibility or the cultural or historical incomprehensibility of the delusional claims. These approaches have neglected formal features of experience that underlie BD and the crucial issue of the nature and validity of BD. In the discussion, we argue that clinical diagnosis of BD cannot be limited to delusional contents alone and requires taking into account the subjective side of BD (how altered experience manifests itself) as well as the conditions of intersubjective encounter (how BD are expressed to and experienced by the clinician). The notion of "bizarreness" in schizophrenia is not purely theoretical; it has practical relevance for the therapeutic encounter and implications on further empirical research and on diagnostic approaches.