Auditory P300 in individuals clinically at risk for psychosis

Dexamphetamine-induced reduction of P3a and P3b in healthy participants

The reduced P3 is one of the most robust deficits involved in schizophrenia. Previous research with catecholaminergic agonists or releasers such as amphetamines have used doses too small to adequately demonstrate an effect on P3. In this study, we gave 0.45 mg/kg dexamphetamine to healthy volunteers (final n = 18) using both auditory and visual three-stimulus P3 procedures. Dexamphetamine significantly reduced P3 amplitudes to auditory target, rare non-target and standard stimulus amplitudes. The reduction in auditory P3 induced by dexamphetamine was proportional across stimulus types to placebo P3 values. There were no effects of dexamphetamine on visual P3. We demonstrate a reduced auditory P3 similar to that seen in schizophrenia and other psychotic illnesses. This possibly reflects a common pathology which is hypothesized within the P3 literature to be related to attention and working memory. Differences between auditory and visual P3 modulation may be related to regional variations in catecholamine or specifically dopamine receptor densities. One specific auditory P3 generator is the superior temporal cortex, an area with dopamine D(2) receptor enriched bands. This is contrasted with visual specific generators, such as the inferior temporal cortex and superior parietal cortex, which do not have these enriched bands.

Multivariate patterns of brain-cognition associations relating to vulnerability and clinical outcome in the at-risk mental states for psychosis

BACKGROUND

Neuropsychological deficits are a core feature of established psychosis and have been previously linked to fronto-temporo-limbic brain alterations. Both neurocognitive and neuroanatomical abnormalities characterize clinical at-risk mental states (ARMS) for psychosis. However, structure-cognition relationships in the ARMS have not been directly explored using multivariate neuroimaging techniques.

METHODS

Voxel-based morphometry and partial least squares were employed to study system-level covariance patterns between whole-brain morphological data and processing speed, working memory, verbal learning/IQ, and executive functions in 40 ARMS subjects and 30 healthy controls (HC). The detected structure-cognition covariance patterns were tested for significance and reliability using non-parametric permutation and bootstrap resampling.

RESULTS

We identified ARMS-specific covariance patterns that described a generalized association of neurocognitive measures with predominantly prefronto-temporo-limbic and subcortical structures as well as the interconnecting white matter. In the conversion group, this generalized profile particularly involved working memory and verbal IQ and was positively correlated with limbic, insular and subcortical volumes as well as negatively related to prefrontal, temporal, parietal, and occipital cortices. Conversely, the neurocognitive profiles in the HC group were confined to working memory, learning and IQ, which were diffusely associated with cortical and subcortical brain regions.

CONCLUSIONS

These findings suggest that the ARMS and prodromal phase of psychosis are characterized by a convergent mapping from multi-domain neurocognitive measures to a set of prefronto-temporo-limbic and subcortical structures. Furthermore, a neuroanatomical separation between positive and negative brain-cognition correlations may not only point to a biological process determining the clinical risk for disease transition, but also to possible compensatory or dysmaturational neural processes.

A roadmap for the development and validation of event-related potential biomarkers in schizophrenia research

New efforts to develop treatments for cognitive dysfunction in mental illnesses would benefit enormously from biomarkers that provide sensitive and reliable measures of the neural events underlying cognition. Here, we evaluate the promise of event-related potentials (ERPs) as biomarkers of cognitive dysfunction in schizophrenia. We conclude that ERPs have several desirable properties: (1) they provide a direct measure of electrical activity during neurotransmission; (2) their high temporal resolutions make it possible to measure neural synchrony and oscillations; (3) they are relatively inexpensive and convenient to record; (4) animal models are readily available for several ERP components; (5) decades of research has established the sensitivity and reliability of ERP measures in psychiatric illnesses; and 6) feasibility of large N (>500) multisite studies has been demonstrated for key measures. Consequently, ERPs may be useful for identifying endophenotypes and defining treatment targets, for evaluating new compounds in animals and in humans, and for identifying individuals who are good candidates for early interventions or for specific treatments. However, several challenges must be overcome before ERPs gain widespread use as biomarkers in schizophrenia research, and we make several recommendations for the research that is necessary to develop and validate ERP-based biomarkers that can have a real impact on treatment development.

Neuropsychological profiles in different at-risk states of psychosis: executive control impairment in the early--and additional memory dysfunction in the late--prodromal state

Impairments in neuropsychological functioning have been described in subjects clinically at high risk for psychosis, but the specific cognitive deficits in different clinical high-risk groups remain to be elucidated. The German Research Network on Schizophrenia employs a heuristic 2-stage model: a putatively late prodromal state (LPS), characterized by the onset of attenuated positive or brief psychotic symptoms, and an early prodromal state (EPS), mainly characterized by the presence of basic symptoms, which are predictive for psychosis within the next 10 years. A total of 205 subjects met the criteria for either an EPS or an LPS of psychosis and were assessed with a comprehensive neuropsychological test battery. Neurocognitive profiles of high-risk groups were compared with data of 87 healthy controls comparable with regard to gender, age, and premorbid verbal IQ. Patients in the LPS were impaired in all neurocognitive domains (memory/learning, executive control/processing speed, and working memory) examined, with memory being the worst. Deficits were less pronounced in patients in the EPS, with a specific deficit in the executive control/processing speed domain. Consistent with a progressive neurodevelopmental disorder, some cognitive abilities were already impaired in patients in the EPS, followed by further deterioration in the LPS. Specifically, deficits in executive control functioning were related to the presence of basic symptoms, indicating a vulnerability for psychosis. Memory deficits were associated with the onset of psychotic symptoms indicating further disease progression in the trajectory to psychosis and, thus, may be useful in predicting psychosis and targeting early intervention.

White matter alterations related to P300 abnormalities in individuals at high risk for psychosis: an MRI-EEG study

BACKGROUND

Psychosis onset is characterized by white matter and electrophysiologic abnormalities. The relation between these factors in the development of illness is almost unknown. We studied the relation between white matter volumes and P300 in prodromal psychosis.

METHODS

We assessed white matter volume (detected using magnetic resonance imaging) and electrophysiologic response during an oddball task (P300) in healthy controls and individuals at high clinical risk for psychosis (with an "at-risk mental state" [ARMS]).

RESULTS

We included 41 controls and 39 patients with an ARMS in our study. A psychotic disorder developed in 26% of the ARMS group within the follow-up period of 2 years. The P300 amplitude was significantly lower in the ARMS group than in the control group. The ARMS group showed reduced volume of white matter underlying the left superior temporal gyrus and the left superior frontal gyrus and increased volume of white matter underlying the right insula and the right angular gyrus compared with controls. Relative to individuals who did not later become psychotic, the subgroup in whom psychosis subsequently developed had a smaller volume of white matter underlying the left precuneus and the right middle temporal gyrus and increased volume in the white matter underlying the right middle frontal gyrus. We observed a significant interaction in the right middle frontal gyrus: white matter volume was negatively associated with P300 amplitude in the ARMS group and positively associated with P300 amplitude in the control group.

LIMITATIONS

The voxel-based morphometry method alone cannot determine whether abnormal white matter volumes are due to an altered number of axonal connections or decreased myelination.

CONCLUSION

P300 abnormalities precede the onset of psychosis and are directly related to white matter alterations, representing a correlate of an increased vulnerability to disease.

Prediction of psychosis by mismatch negativity

BACKGROUND

To develop risk-adapted prevention of psychosis, an accurate estimation of the individual risk of psychosis at a given time is needed. Inclusion of biological parameters into multilevel prediction models is thought to improve predictive accuracy of models on the basis of clinical variables. To this aim, mismatch negativity (MMN) was investigated in a sample clinically at high risk, comparing individuals with and without subsequent conversion to psychosis.

METHODS

At baseline, an auditory oddball paradigm was used in 62 subjects meeting criteria of a late risk at-state who remained antipsychotic-naive throughout the study. Median follow-up period was 32 months (minimum of 24 months in nonconverters, n = 37). Repeated-measures analysis of covariance was employed to analyze the MMN recorded at frontocentral electrodes; additional comparisons with healthy controls (HC, n = 67) and first-episode schizophrenia patients (FES, n = 33) were performed. Predictive value was evaluated by a Cox regression model.

RESULTS

Compared with nonconverters, duration MMN in converters (n = 25) showed significantly reduced amplitudes across the six frontocentral electrodes; the same applied in comparison with HC, but not FES, whereas the duration MMN in in nonconverters was comparable to HC and larger than in FES. A prognostic score was calculated based on a Cox regression model and stratified into two risk classes, which showed significantly different survival curves.

CONCLUSIONS

Our findings demonstrate the duration MMN is significantly reduced in at-risk subjects converting to first-episode psychosis compared with nonconverters and may contribute not only to the prediction of conversion but also to a more individualized risk estimation and thus risk-adapted prevention.

[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.

Auditory ERP components before and after transition to a first psychotic episode

We investigated the course of Event Related Potentials (ERP) from prior to until shortly after a first psychotic episode in subjects at Ultra High Risk (UHR) for psychosis. N1, N2, N2b, P2 and P3 amplitudes were assessed using an auditory active oddball paradigm in 15 UHR subjects who made a transition to psychosis (UHR+T) at follow up, 23 subjects without a transition (UHR+NT) and 17 matched healthy controls at inclusion and again after approximately 18 months. Repeated-measures analyses revealed no significant time effects for any of the ERP components. However, an interaction effect was found for N1 amplitudes. Post-hoc analyses showed that N1 amplitudes were smaller at follow up compared to baseline only in UHR+T subjects. P3 amplitudes showed no further reduction after psychotic onset. These findings suggest that discernable ERP components behave differently during progression from the prodromal phase to the first psychotic episode. These findings may give insight in pathophysiological mechanisms underlying the genesis of psychosis.

Gray matter alterations related to P300 abnormalities in subjects at high risk for psychosis: longitudinal MRI-EEG study

BACKGROUND

Psychotic disorders are characterized by gray matter and volumetric and electrophysiological abnormalities. The relationship between these factors in the onset of psychotic illness is unclear.

METHODS

Eighty English-native right-handed subjects (39 subjects at ultra high risk for psychosis "ARMS" and 41 healthy volunteers) were scanned with MRI, and studied using EEG during an oddball task. Both assessments were performed at first clinical presentation. The ARMS subjects were then followed clinically, with the MRI and EEG assessments repeated in a subgroup of each sample.

RESULTS

The P300 amplitude at presentation was significantly lower in the ARMS subjects than in controls. At baseline, the ARMS group showed reduced gray matter volume relative to controls in the right superior frontal gyrus, left medial frontal gyrus, left inferior frontal gyrus, right orbital gyrus and right supramarginal gyrus. Transition to psychosis (26%) was associated with reduced gray matter in the right inferior parietal lobule and in the left parahippocampal gyrus. Within the ARMS group, there was a positive correlation between P300 amplitude and gray matter volume in the right supramarginal gyrus. A significant group by P300 by gray matter interaction was detected in the left medial frontal gyrus. Longitudinal assessment revealed progressive gray matter alterations in prefrontal and subcortical areas of the ARMS but no significant changes in P300 amplitude over time.

CONCLUSIONS

P300 abnormalities in the ARMS are related to alterations in regional gray matter volume and represent a correlate of an increased vulnerability to psychosis.

Neuroanatomical correlates of executive dysfunction in the at-risk mental state for psychosis

Deficits in executive functioning have been described as a core feature of schizophrenia and have been linked to patterns of fronto-temporo-limbic brain alterations. To date, such structure-cognition relationships have not been explored in a clinically defined at-risk mental state (ARMS) for psychosis using whole-brain neuroimaging techniques. Therefore, we used voxel-based morphometry in 40 ARMS and 30 matched healthy control (HC) individuals to investigate whether gray and white matter volumes (1) correlated with the performance in the Trail-Making Test B (TMT-B), an established measure of executive functioning, and (2) were volumetrically linked to the ventromedial prefrontal cortex (VMPFC), found to be associated with TMT-B in the ARMS during the first analysis step. We found the ARMS subjects to be specifically impaired in their TMT-B performance versus HC. Brain-cognition associations involving the insular cortices were observed in the HC, but not in the ARMS individuals. Conversely, TMT-B correlations in the VMPFC, the cerebellum, the fronto-callosal white matter were detected in the ARMS, but not the HC group. The VMPFC was linked to the temporo-limbic cortices in HC, whereas the connectivity pattern in the ARMS involved the left temporal and dorsolateral prefrontal cortex, the cerebellum, the right SMA and extended portions of the fronto-callosal white matter. These findings suggest that executive deficits are already present in the ARMS for psychosis and may be subserved by structurally altered networks of interconnected cortical and subcortical brain regions in line with the disconnectivity hypothesis of schizophrenia.

Use of neuroanatomical pattern regression to predict the structural brain dynamics of vulnerability and transition to psychosis

BACKGROUND

The at-risk mental state for psychosis (ARMS) has been associated with abnormal structural brain dynamics underlying disease transition or non-transition. To date, it is unknown whether these dynamic brain changes can be predicted at the single-subject level prior to disease transition using MRI-based machine-learning techniques.

METHODS

First, deformation-based morphometry and partial-least-squares (PLS) was used to investigate patterns of volumetric changes over time in 25 ARMS individuals versus 28 healthy controls (HC) (1) irrespective of the clinical outcome and (2) according to illness transition or non-transition. Then, the baseline MRI data were employed to predict the expression of these volumetric changes at the individual level using support-vector regression (SVR).

RESULTS

PLS revealed a pattern of pronounced morphometric changes in ARMS versus HC that affected predominantly the right prefrontal, as well as the perisylvian, parietal and periventricular structures (p<0.011), and that was more pronounced in the converters versus the non-converters (p<0.010). The SVR analysis facilitated a reliable prediction of these longitudinal brain changes in individual out-of training cases (HC vs ARMS: r=0.83, p<0.001; HC vs converters vs non-converters: r=0.83, p<0.001) by relying on baseline patterns that involved ventricular enlargements, as well as prefrontal, perisylvian, limbic, parietal and subcortical volume reductions.

CONCLUSIONS

Abnormal brain changes over time may underlie an elevated vulnerability for psychosis and may be most pronounced in subsequent converters to psychosis. Pattern regression techniques may facilitate an accurate prediction of these structural brain dynamics, potentially allowing for an early recognition of individuals at risk of developing psychosis-associated neuroanatomical changes over time.

EEG spectral power and negative symptoms in at-risk individuals predict transition to psychosis

INTRODUCTION

EEG power in the delta, theta and beta1 bands has been shown to be positively correlated with negative symptoms in first episode psychotic patients. The present study investigates this correlation in an "at risk mental state for psychosis" (ARMS) with the aim to improve prediction of transition to psychosis.

METHODS

Thirteen ARMS patients with later transition to psychosis (ARMS-T) and fifteen without (follow-up period of at least 4 years) (ARMS-NT) were investigated using spectral resting EEG data (of 8 electrodes over the fronto-central scalp area placed according to the 10-20 system) and summary score of the Scale for the Assessment of Negative Symptoms (SANS). Linear regressions were used to evaluate the correlation of SANS and EEG power in seven bands (delta, theta, alpha1, alpha2, beta1, beta2, beta3) in both ARMS groups and logistic regressions were used to predict transition to psychosis. Potentially confounding factors were controlled.

RESULTS

ARMS-T and ARMS-NT showed differential correlations of EEG power and SANS in delta, theta, and beta1 bands (p<.05): ARMS-T showed positive and ARMS-NT negative correlations. Logistic regressions showed that neither SANS score nor EEG spectral power alone predicted transition to psychosis. However, SANS score in combination with power in the delta, theta, beta1, and beta2 bands, respectively, predicted transition significantly (p<.03).

CONCLUSIONS

ARMS-T and ARMS-NT show differential correlations of SANS summary score and EEG power in delta, theta, and beta bands. Prediction of transition to psychosis is possible using combined information from a negative symptom scale and EEG spectral data.

Reduced parietal P300 amplitude is associated with an increased risk for a first psychotic episode

BACKGROUND

P300 abnormalities indicate changes in information processing and are one of the most reliable biological markers of schizophrenia. We sought to investigate whether abnormalities in P300 (P3) or other event-related potentials are also present in subjects at ultra high risk (UHR) for developing psychosis and whether they are helpful in predicting transition to psychosis.

METHODS

The N1, N2, N2b, P2, and P3 amplitudes were assessed in 61 UHR subjects, of whom 18 subjects (30%) made a transition to psychosis over a 3-year follow-up period (UHR + T: age 20.4 years) and 43 (70%) did not (UHR + NT: age 19.3 years), and 28 age- and intelligence-matched healthy control subjects (age 20.0 years). Psychopathology was also assessed.

RESULTS

The UHR + T subjects showed smaller parietal P3 amplitudes, compared with control subjects and UHR + NT subjects. Moreover, the N2b was higher in control subjects compared with both UHR groups. We found no differences in N1 or P2 components between the groups, and our UHR subjects did not exhibit bilateral P3 asymmetry. Reduced P3 amplitudes were the best predictor for subsequent psychosis in the UHR group. The P3 reduction was related to increased social anhedonia and withdrawal and a lower global assessment of social functioning and social personal adjustment.

CONCLUSIONS

The UHR + T subjects showed reduced parietal P3 amplitudes. In addition, a reduced P3 amplitude was the best predictor for subsequent psychosis. If replicated, these findings might contribute to a more accurate prediction of a first psychotic episode. Furthermore, reduced social functioning might be related to information processing deficits in UHR subjects.

Increased saccadic rate during smooth pursuit eye movements in patients at Ultra High Risk for developing a psychosis

Abnormalities in eye tracking are consistently observed in schizophrenia patients and their relatives and have been proposed as an endophenotype of the disease. The aim of this study was to investigate the performance of patients at Ultra High Risk (UHR) for developing psychosis on a task of smooth pursuit eye movement (SPEM). Forty-six UHR patients and twenty-eight age and education matched controls were assessed with a task of SPEM and psychiatric questionnaires. Our results showed that both the corrective and non-corrective saccadic rates during pursuit were higher in the UHR group. There were however no differences in smooth pursuit gain between the two groups. The saccadic rate was related to positive UHR symptoms. Our findings indicate that abnormalities in SPEM are already present in UHR patients, prior to a first psychotic episode. These abnormalities occur only in the saccadic system.

Genetics and intermediate phenotypes of the schizophrenia--bipolar disorder boundary

Categorization of psychotic illnesses into schizophrenic and affective psychoses remains an ongoing controversy. Although Kraepelinian subtyping of psychosis was historically beneficial, modern genetic and neurophysiological studies do not support dichotomous conceptualization of psychosis. Evidence suggests that schizophrenia and bipolar disorder rather present a clinical continuum with partially overlapping symptom dimensions, neurophysiology, genetics and treatment responses. Recent large scale genetic studies have produced inconsistent findings and exposed an urgent need for re-thinking phenomenology-based approach in psychiatric research. Epidemiological, linkage and molecular genetic studies, as well as studies in intermediate phenotypes (neurocognitive, neurophysiological and anatomical imaging) in schizophrenia and bipolar disorders are reviewed in order to support a dimensional conceptualization of psychosis. Overlapping and unique genetic and intermediate phenotypic signatures of the two psychoses are comprehensively recapitulated. Alternative strategies which may be implicated into genetic research are discussed.

Research in people with psychosis risk syndrome: a review of the current evidence and future directions

After decades of research, schizophrenia and related psychotic disorders are still among the most debilitating disorders in medicine. The chronic illness course in most individuals, greater treatment responsiveness during the first episode, progressive gray matter decline during early disease stages, and retrospective accounts of 'prodromal' or early illness signs and symptoms formed the basis for research on the psychosis risk syndrome (PRS), known variably as 'clinical high risk' (CHR), or 'ultra-high risk' (UHR), or 'prodromal'. The pioneering era of research on PRS focused on the development and validation of specific assessment tools and the delineation of high risk criteria. This was followed by the examination of conversion rates in psychosis risk cohorts followed naturalistically, identification of predictors of conversion to psychosis, and investigation of interventions able to abort or delay the development of full psychosis. Despite initially encouraging results concerning the predictive validity of PRS criteria, recent findings of declining conversion rates demonstrate the need for further investigations. Results from intervention studies, mostly involving second-generation antipsychotics and cognitive behavioral therapy, are encouraging, but are currently still insufficient to make treatment recommendations for this early, relatively non-specific illness phase. The next phase of research on PRS, just now beginning, has moved to larger, 'multisite' projects to increase generalizability and to ensure that sufficiently large samples at true risk for psychosis are included. Emphasis in these emerging studies is on: 1) identification of biomarkers for conversion to psychosis; 2) examination of non-antipsychotic, neuroprotective and low-risk pharmacologic and non-pharmacologic interventions; 3) testing of potentially phase-specific interventions; 4) examination of the relationship between treatment response during PRS and prognosis for the course of illness; 5) follow-up of patients who developed schizophrenia despite early interventions and comparison of illness trajectories with patients who did not receive early interventions; 6) characterization of individuals with outcomes other than schizophrenia-spectrum disorders, such as bipolar disorder and remission from PRS, including false positive cases; and 7) assessment of meaningful social and role functioning outcomes. While the research conducted to date has already yielded crucial information, the translation of the concept of a clinically identifiable PRS into clinical practice does not seem justified at this point.

Increased cortical inhibition deficits in first-episode schizophrenia with comorbid cannabis abuse

RATIONALE/OBJECTIVES

There is a high prevalence of substance use disorder (SUD) in first-episode schizophrenia (SZ), but its contribution to the underlying SZ pathophysiology remains unclear. Several studies using transcranial magnetic stimulation (TMS) have observed abnormalities in human motor cortex (M1) excitability in SZ. Studies on cortical excitability comparing SZ patients with and without comorbid substance abuse are lacking.

METHODS

A total of 29 first-episode SZ patients participated in this study; 12 had a history of comorbid cannabis abuse (SZ-SUD) and 17 did not (SZ-NSUD). We applied TMS to right and left M1 areas to assess the resting motor threshold (RMT), short-interval cortical inhibition (SICI), intracortical facilitation (ICF), and the contralateral cortical silent period (CSP).

RESULTS

In SICI and ICF conditions, right M1 stimulation led to significantly higher motor evoked potential ratios in SZ-SUD compared to SZ-NSUD. This suggests lower cortical inhibition and increased ICF in first-episode SZ with previous cannabis abuse. There were no group differences in RMT and CSP duration. Neither were there any significant correlations between psychopathology (as indexed by Positive and Negative Syndrome Scale), disease characteristics, the extent of cannabis abuse, and TMS parameters (SICI, ICF, and CSP).

CONCLUSIONS

Comorbid cannabis abuse may potentiate the reduced intracortical inhibition and enhanced ICF observed in first-episode SZ patients in some previous studies. This finding suggests an increased alteration of GABA(A) and NMDA receptor activity in cannabis-abusing first-episode patients as compared to schizophrenia patients with no history of substance abuse. This may constitute a distinct vulnerability factor in this special population.

Neuroanatomical correlates of different vulnerability states for psychosis and their clinical outcomes

BACKGROUND

Structural brain abnormalities have been described in individuals with an at-risk mental state for psychosis. However, the neuroanatomical underpinnings of the early and late at-risk mental state relative to clinical outcome remain unclear.

AIMS

To investigate grey matter volume abnormalities in participants in a putatively early or late at-risk mental state relative to their prospective clinical outcome.

METHOD

Voxel-based morphometry of magnetic resonance imaging data from 20 people with a putatively early at-risk mental state (ARMS-E group) and 26 people with a late at-risk mental state (ARMS-L group) as well as from 15 participants with at-risk mental states with subsequent disease transition (ARMS-T group) and 18 participants without subsequent disease transition (ARMS-NT group) were compared with 75 healthy volunteers.

RESULTS

Compared with healthy controls, ARMS-L participants had grey matter volume losses in frontotemporolimbic structures. Participants in the ARMS-E group showed bilateral temporolimbic alterations and subtle prefrontal abnormalities. Participants in the ARMS-T group had prefrontal alterations relative to those in the ARMS-NT group and in the healthy controls that overlapped with the findings in the ARMS-L group.

CONCLUSIONS

Brain alterations associated with the early at-risk mental state may relate to an elevated susceptibility to psychosis, whereas alterations underlying the late at-risk mental state may indicate a subsequent transition to psychosis.

Use of neuroanatomical pattern classification to identify subjects in at-risk mental states of psychosis and predict disease transition

CONTEXT

Identification of individuals at high risk of developing psychosis has relied on prodromal symptomatology. Recently, machine learning algorithms have been successfully used for magnetic resonance imaging-based diagnostic classification of neuropsychiatric patient populations.

OBJECTIVE

To determine whether multivariate neuroanatomical pattern classification facilitates identification of individuals in different at-risk mental states (ARMS) of psychosis and enables the prediction of disease transition at the individual level.

DESIGN

Multivariate neuroanatomical pattern classification was performed on the structural magnetic resonance imaging data of individuals in early or late ARMS vs healthy controls (HCs). The predictive power of the method was then evaluated by categorizing the baseline imaging data of individuals with transition to psychosis vs those without transition vs HCs after 4 years of clinical follow-up. Classification generalizability was estimated by cross-validation and by categorizing an independent cohort of 45 new HCs.

SETTING

Departments of Psychiatry and Psychotherapy, Ludwig-Maximilians-University, Munich, Germany.

PARTICIPANTS

The first classification analysis included 20 early and 25 late at-risk individuals and 25 matched HCs. The second analysis consisted of 15 individuals with transition, 18 without transition, and 17 matched HCs.

MAIN OUTCOME MEASURES

Specificity, sensitivity, and accuracy of classification.

RESULTS

The 3-group, cross-validated classification accuracies of the first analysis were 86% (HCs vs the rest), 91% (early at-risk individuals vs the rest), and 86% (late at-risk individuals vs the rest). The accuracies in the second analysis were 90% (HCs vs the rest), 88% (individuals with transition vs the rest), and 86% (individuals without transition vs the rest). Independent HCs were correctly classified in 96% (first analysis) and 93% (second analysis) of cases.

CONCLUSIONS

Different ARMSs and their clinical outcomes may be reliably identified on an individual basis by assessing patterns of whole-brain neuroanatomical abnormalities. These patterns may serve as valuable biomarkers for the clinician to guide early detection in the prodromal phase of psychosis.

Evidence, evidence-based medicine, and evidence utility in psychiatry and electrophysiology

In this issue a series of outstanding and comprehensive reviews of the progress of electrophysiological biomarkers or endophenotype indicators in psychiatric illnesses is presented. These reviews establish presence of electrophysiological abnormalities in symptom-based diagnoses of schizophrenia, dementia, anxiety disorders, substance abuse, and childhood disorders. Diagnostic sensitivity and specificity remain modest in most studies as may be expected for the relationship of indicators of underlying dimensions of brain organization and function when compared by interview-obtained symptom assessment. The power of electrophysiology to mirror pharmacological effects and treatment susceptability is an important resarch direction for electrophysiology.