The MATRICS Consensus Cognitive Battery, part 2: co-norming and standardization

OBJECTIVE

The consensus cognitive battery developed by the National Institute of Mental Health's (NIMH's) Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative includes 10 independently developed tests that are recommended as the standard battery for clinical trials of cognition-enhancing interventions for schizophrenia. To facilitate interpretation of results from the MATRICS Consensus Cognitive Battery using a common scaling across tests, normative data were obtained from a single representative U.S. community sample with the battery administered as a unit.

METHOD

The MATRICS Consensus Cognitive Battery was administered to 300 individuals from the general community at five sites in differing geographic regions. For each site, recruitment was stratified by age, gender, and education. A scientific survey sampling method was used to help avoid sampling bias. The battery was administered in a standard order to each participant in a single session lasting approximately 60 minutes. Descriptive data were generated, and age, gender, and education effects on performance were examined.

RESULTS

Prominent age and education effects were observed across tests. The results for gender differed by measure, suggesting the need for age and gender corrections in clinical trials. The MATRICS Consensus Cognitive Battery components were co-normed, with allowance for demographic corrections.

CONCLUSIONS

Co-norming a battery such as the MATRICS Consensus Cognitive Battery, comprising tests from independent test developers each with their own set of norms, facilitates valid interpretation of test scores and communication of findings across studies. These normative data will aid in estimating the magnitude of change during clinical trials of cognition-enhancing agents and make it possible to derive more directly interpretable composite scores.

Functional co-primary measures for clinical trials in schizophrenia: results from the MATRICS Psychometric and Standardization Study

OBJECTIVE

During the consensus meetings of the National Institute of Mental Health Measurement and Treatment Research to Improve Cognition in Schizophrenia (NIMH-MATRICS) Initiative, the U.S. Food and Drug Administration took the position that a drug for this purpose should show changes on 1) an accepted consensus cognitive performance measure and 2) an additional measure (i.e., a co-primary) that is considered functionally meaningful. The goal of the current study was to describe steps to evaluate four potential co-primary measures for psychometric properties and validity.

METHOD

As part of the five-site MATRICS Psychometric and Standardization Study (PASS), two measures of functional capacity and two interview-based measures of cognition were evaluated in 176 patients with schizophrenia (167 of these patients were retested 4 weeks later).

RESULTS

Data are presented for each co-primary measure for test-retest reliability, utility as a repeated measure, relationship to cognitive performance, relationship to functioning, tolerability/practicality, and number of missing data.

CONCLUSIONS

Psychometric properties of all of the measures were considered acceptable, and the measures were generally comparable across the various criteria, except that the functional capacity measures had stronger relationships to cognitive performance and fewer missing data. The development and evaluation of potential co-primary measures is still at an early stage, and it was decided not to endorse a single measure for clinical trials at this point. The current findings offer the initial steps to identify functionally meaningful co-primary measures in this area and will help to guide further evaluation of such measures.

The MATRICS Consensus Cognitive Battery, part 1: test selection, reliability, and validity

OBJECTIVE

The lack of an accepted standard for measuring cognitive change in schizophrenia has been a major obstacle to regulatory approval of cognition-enhancing treatments. A primary mandate of the National Institute of Mental Health's Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative was to develop a consensus cognitive battery for clinical trials of cognition-enhancing treatments for schizophrenia through a broadly based scientific evaluation of measures.

METHOD

The MATRICS Neurocognition Committee evaluated more than 90 tests in seven cognitive domains to identify the 36 most promising measures. A separate expert panel evaluated the degree to which each test met specific selection criteria. Twenty tests were selected as a beta battery. The beta battery was administered to 176 individuals with schizophrenia and readministered to 167 of them 4 weeks later so that the 20 tests could be compared directly.

RESULTS

The expert panel ratings are presented for the initially selected 36 tests. For the beta battery tests, data on test-retest reliability, practice effects, relationships to functional status, practicality, and tolerability are presented. Based on these data, 10 tests were selected to represent seven cognitive domains in the MATRICS Consensus Cognitive Battery.

CONCLUSIONS

The structured consensus method was a feasible and fair mechanism for choosing candidate tests, and direct comparison of beta battery tests in a common sample allowed selection of a final consensus battery. The MATRICS Consensus Cognitive Battery is expected to be the standard tool for assessing cognitive change in clinical trials of cognition-enhancing drugs for schizophrenia. It may also aid evaluation of cognitive remediation strategies.

Does the Central Bottleneck Encompass Voluntary Selection of Hedonically Based Choices?

A large literature on multitasking bottlenecks suggests that people cannot generally make decisions or select responses in two different tasks at the same time. However, these tasks have all involved retrieving preinstructed responses, rather than spontaneously choosing actions based on anticipated hedonic consequences. To assess whether the same bottlenecks encompasses voluntary choices, a gambling decision was utilized as the second of two tasks in a psychological refractory period (PRP) design. Three decision-related factors were identified that affected latency of responding in the gambling task. All proved to be additive with stimulus-onset asynchrony (SOA) in dual-task blocks. The results indicate that making a choice to try to optimize outcomes is subject to the same processing bottleneck as the retrieval of preinstructed responses that has been the mainstay of attention and performance research.

Initial heritability analyses of endophenotypic measures for schizophrenia: the consortium on the genetics of schizophrenia

CONTEXT

Exploration of the genetic architecture of specific endophenotypes may be a powerful strategy for understanding the genetic basis of schizophrenia.

OBJECTIVE

To characterize the genetic architecture of some key endophenotypic measures selected for their reported heritabilities in schizophrenia.

DESIGN

Family-based heritability study.

SETTING

Seven sites across the United States.

PARTICIPANTS

At the time of these initial data analyses, the members of 183 nuclear families ascertained through probands with schizophrenia had been assessed for these endophenotypes.

MAIN OUTCOME MEASURES

Variance component models were used to assess the heritability of and the environmental and genetic correlations among the endophenotypes. The Consortium on the Genetics of Schizophrenia assesses the neurophysiologic measures of prepulse inhibition of acoustic startle, P50 event-related potential suppression, and the antisaccade task for eye movements and the neurocognitive measures of the Continuous Performance Test (Degraded Stimulus version), the California Verbal Learning Test, the Letter-Number Sequencing test, and 6 measures from the University of Pennsylvania Computerized Neurocognitive Battery. The heritabilities of these 12 measures are the focus of this article.

RESULTS

All of the endophenotypes and the University of Pennsylvania Computerized Neurocognitive Battery measures were found to be significantly heritable (P < or = .005), with heritabilities ranging from 24% to 55%. Significant environmental and genetic correlations were also observed between many of the endophenotypic measures.

CONCLUSION

This is the first large-scale, multisite, family-based heritability study of a collection of endophenotypes for schizophrenia and suggests that endophenotypes are important measures to consider in characterizing the genetic basis of schizophrenia.

Differential effects of typical and atypical antipsychotics on brain myelination in schizophrenia

CONTEXT

Imaging and post-mortem studies provide converging evidence that patients with schizophrenia have a dysregulated developmental trajectory of frontal lobe myelination even in adulthood. Atypical antipsychotics have been shown to have a wide spectrum of efficacy across multiple psychiatric diseases and to be particularly efficacious in treatment resistant cases of disorders such as schizophrenia.

OBJECTIVE

To test the a priori hypothesis that antipsychotic medications may differentially impact frontal lobe myelination in patients with schizophrenia.

DESIGN, SETTING, AND PARTICIPANTS

Participants ranged in age from 18-35 years, were all male, and were recruited by a single group of investigators using the same criteria. Two cohorts of subjects with schizophrenia early in their disease who were treated either with oral risperidone (Ris) or fluphenazine decanoate (Fd) were imaged in conjunction with cohorts of healthy controls. Each cohort was imaged using a different MRI instrument using identical imaging sequences.

MAIN OUTCOME MEASURE

MRI measures of frontal lobe white matter volume.

RESULTS

We estimated differences due to differences in the MRI instruments used in the two studies in the two healthy control groups matched to the patient samples, adjusting for age and other covariates. We then statistically removed those differences (which we assumed were due to instrument effects) from the data in the schizophrenia samples by subtraction. Relative to the differences seen in controls, the two groups of schizophrenic patients differed in their pattern of frontal lobe structure with the Ris-treated group having significantly larger white matter volume than the Fd group.

CONCLUSIONS

The results suggest that the choice of antipsychotic treatment may differentially impact brain myelination in adults with schizophrenia. Prospective studies are needed to confirm this finding. MRI can be used to dissect subtle differences in brain tissue characteristics and thus could help clarify the effect of pharmacologic treatments on neurodevelopmental and pathologic processes in vivo.

Effects of cigarette smoking on prepulse inhibition, its attentional modulation, and vigilance performance

Startle eyeblink modification was measured during a degraded stimulus continuous performance test following both smoking and overnight abstinence among student smokers to measure the effects of smoking on both early and late attentional processes. A group of nonsmokers was tested twice without nicotine manipulation. A startling noise was presented either 240 or 1200 ms following target and nontarget stimuli presented during the task. Startle inhibition at 240 ms was greater following targets than nontargets following smoking and during both nonsmoker tests, but this attentional modulation was absent following abstinence. At the 1200-ms probe position, target and nontarget stimuli produced nondifferential inhibition during both tests for both groups. Abstinence among smokers produced reliably lower vigilance performance compared to ad lib smoking. The results indicate that smoking abstinence affects the early stages of stimulus processing.

Multi-site studies of acoustic startle and prepulse inhibition in humans: initial experience and methodological considerations based on studies by the Consortium on the Genetics of Schizophrenia

BACKGROUND

Startle and its inhibition by weak lead stimuli ("prepulse inhibition": PPI) are studied to understand the neurobiology of information processing in patients and community comparison subjects (CCS). PPI has a strong genetic basis in infrahumans, and there is evidence for its heritability, stability and reliability in humans. PPI has gained increasing use as an endophenotype to identify vulnerability genes for brain disorders, including schizophrenia. Genetic studies now often employ multiple, geographically dispersed test sites to accommodate the need for large and complex study samples. Here, we assessed the feasibility of using PPI in multi-site studies.

METHODS

Within a 7-site investigation with multiple measures, the Consortium on the Genetics of Schizophrenia conducted a methodological study of acoustic startle and PPI in CCS. Methods were manualized, videotaped and standardized across sites with intensive in-person training sessions. Equipment was acquired and programmed at the "PPI site" (UCSD), and stringent quality assurance (QA) procedures were used. Testing was completed on 196 CCS over 2.5 years, with 5 primary startle dependent measures: eyeblink startle magnitude, habituation, peak latency, latency facilitation and PPI.

RESULTS

Analyses identified significant variability across sites in some but not all primary measures, and determined factors both within the testing process and subject characteristics that influenced a number of test measures. QA procedures also identified non-standardized practices with respect to testing methods and procedural "drift", which may be particularly relevant to multi-site studies using these measures.

CONCLUSION

With thorough oversight and QA procedures, measures of acoustic startle PPI can be acquired reliably across multiple testing sites. Nonetheless, even among sites with substantial expertise in utilizing psychophysiological measures, multi-site studies using startle and PPI as dependent measures require careful attention to methodological procedures.

Avoidant personality disorder is a separable schizophrenia-spectrum personality disorder even when controlling for the presence of paranoid and schizotypal personality disorders The UCLA family study

It is unresolved whether avoidant personality disorder (APD) is an independent schizophrenia (Sz)-spectrum personality disorder (PD). Some studies find APD and social anxiety symptoms (Sxs) to be separable dimensions of psychopathology in relatives (Rels) of schizophrenics while other studies find avoidant Sxs to be correlated with schizotypal and paranoid Sxs. Rates of APD among first-degree Rels of Sz probands, attention-deficit/hyperactivity disorder (ADHD) probands, and community control (CC) probands were examined. Further analyses examined rates when controlling for the presence of schizotypal (SPD) and paranoid (PPD) personality disorders, differences in APD Sxs between relative groups, and whether APD in Rels of Szs reflects a near miss for another Sz-spectrum PD. Three hundred sixty-two first-degree Rels of Sz probands, 201 relatives of ADHD probands, and 245 Rels of CC probands were interviewed for the presence of DSM-III-R Axis I and II disorders. Diagnoses, integrating family history, interview information, and medical records, were determined. APD occurred more frequently in Rels of Sz probands compared to CC probands (p<0.001) and also when controlling for SPD and PPD (p<0.005). Two Sxs of APD were most characteristic of the Rels of Sz probands: "avoids social or occupational activities..." and "exaggerates the potential difficulties..." 65% of the Rels of Sz probands who had diagnoses of APD were more than one criterion short of a DSM-III-R diagnosis of either SPD or PPD. This indicates that APD is a separate Sz-spectrum disorder, and not merely a sub-clinical form of SPD or PPD.

Translating basic attentional paradigms to schizophrenia research: reconsidering the nature of the deficits

Abnormalities in attention have long been viewed as one of the fundamental underlying cognitive deficits in schizophrenia, likely contributing both to formation of some types of symptoms and particularly to the substantial work and social impairments that often accompany schizophrenia. Yet, the precise nature of the attentional deficits in schizophrenia remains poorly understood. Translating advances in cognitive psychology to clinical research brings paradigms with greater analytic power to the study of attention in schizophrenia. In particular, these paradigms should shed light on whether the attentional dysfunction in schizophrenia is best conceptualized as arising from limitations in amount or allocation of processing capacity or from more specific structural bottlenecks that do not allow certain processes to be carried out in two tasks simultaneously. Certain types of dual-task paradigms are particularly well suited to make distinctive predictions, particularly those involving a psychological refractory period paradigm. The background and design of a series of ongoing studies of prodromal, first-episode, and chronic schizophrenia patients are described that are addressing the developmental course of attentional dysfunction in this disorder. These refined paradigms should substantially increase our understanding of the specific forms of attentional impairment characterizing schizophrenia and their connections to symptom development and functional outcome.

The Consortium on the Genetics of Endophenotypes in Schizophrenia: model recruitment, assessment, and endophenotyping methods for a multisite collaboration

BACKGROUND

The Consortium on the Genetics of Schizophrenia (COGS) is an ongoing, National Institute of Mental Health-funded, 7-site collaboration investigating the occurrence and genetic architecture of quantitative endophenotypes related to schizophrenia. The purpose of this article is to provide a description of the COGS structure and methods, including participant recruitment and assessment.

METHODS

The hypothesis-driven recruitment strategy ascertains families that include a proband with a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnosis of schizophrenia, and at least one unaffected full sibling available for genotyping and endophenotyping, along with parents available for genotyping and (optional depending on age) endophenotyping. The family structure is selected to provide contrast in quantitative endophenotypic traits and thus to maximize the power of the planned genetic analyses. Probands are recruited from many sources including clinician referrals, local National Alliance for the Mentally Ill chapters, and advertising via the media. All participants undergo a standardized protocol that includes clinical characterization, a blood draw for genotyping, and endophenotype assessments (P50 suppression, prepulse inhibition, antisaccade performance, continuous performance tasks, letter-number span, verbal memory, and a computerized neurocognitive battery). Investigators participate in weekly teleconferences to coordinate and evaluate recruitment, clinical assessment, endophenotyping, and continuous quality control of data gathering and analyses. Data integrity is maintained through use of a highly quality-assured, centralized web-based database.

RESULTS

As of February 2006, 355 families have been enrolled and 688 participants have been endophenotyped, including schizophrenia probands (n = 154, M:F = 110:44), first-degree biological relatives (n = 343, M:F = 151:192), and community comparison subjects (n = 191, M:F = 81:110).

DISCUSSION

Successful multisite genetics collaborations must institute standardized methodological criteria for assessment and recruitment that are clearly defined, well communicated, and uniformly applied. In parallel, studies utilizing endophenotypes require strict adherence to criteria for cross-site data acquisition, equipment calibration and testing and software equivalence, and continuous quality assurance for many measures obtained across sites. This report describes methods and presents the structure of the COGS as a model of multisite endophenotype genetic studies. It also provides demographic information after the first 2 years of data collection on a sample for whom the behavioral data and genetics of endophenotype performance will be fully characterized in future articles. Some issues discussed in the reviews that follow reflect the challenges of evaluating endophenotypes in studies of the genetic architecture of endophenotypes in schizophrenia.

The Consortium on the Genetics of Schizophrenia: neurocognitive endophenotypes

The Consortium on the Genetics of Schizophrenia (COGS) is a 7-site collaboration that examines the genetic architecture of quantitative endophenotypes in families with schizophrenia. Here we review the background and rationale for selecting neurocognitive tasks as endophenotypic measures in genetic studies. Criteria are outlined for the potential of measures as endophenotypic vulnerability markers. These include association with illness, state independence (ie, adequate test-retest stability, adequate between-site reliability, impairments in patients not due to medications, impairments observed regardless of illness state), heritability, findings of higher rates in relatives of probands than in the general population, and cosegregation within families. The COGS required that, in addition, the measures be "neurocognitive" and thus linked to neurobiology and that they be feasible in multisite studies. The COGS neurocognitive assessment includes measures of attention, verbal memory, working memory, and a computerized neurocognitive battery that also includes facial processing tasks. Here we describe data demonstrating that these neurobehavioral measures meet criteria for endophenotypic candidacy. We conclude that quantitative neurocognitive endophenotypes need further evidence for efficacy in identifying genetic effects but have the potential of providing unprecedented insight into gene-environment interaction related to dimensions of brain and behavior in health and disease.

Successful multi-site measurement of antisaccade performance deficits in schizophrenia

The antisaccade task is a promising schizophrenia endophenotype; it is stable over time and reflects neurophysiological deficits present in both schizophrenia subjects and their first-degree relatives. Meaningful genetic research requires large sample sizes that are best ascertained using multi-site study designs. To establish the criterion validity of the antisaccade task in a multi-site design, the Consortium on the Genetics of Schizophrenia (COGS) examined whether seven sites could detect previously reported antisaccade deficits in schizophrenia subjects. Investigators presented 3 blocks of 20 antisaccade stimuli to 143 schizophrenia subjects and 195 comparison subjects. Frequent collaborator communication, standardized training, and ongoing quality assurance optimized testing uniformity. Data were discarded from only 1.2% of subjects due to poor quality, reflecting the high fidelity of data collection and scoring methods. All sites detected a significant difference in the proportion of correct antisaccades between schizophrenia and comparison subjects (p<.02 at all sites); group differences in gain and latency were less robust. Regression analyses to adjust for the effects of group, site, age, gender, smoking, and parental education on the proportion of correct antisaccades revealed a significant effect of group, site, and age but no effect of gender, smoking, or parental education, and no group-by-site interactions. Intraclass correlations between proportion of correct antisaccades across the blocks of stimuli ranged from 0.87 to 0.93, demonstrating good within-session reliability at sites. These results confirm previous findings of antisaccade deficits in schizophrenia subjects and support the use of the antisaccade task as a potential schizophrenia endophenotype in multi-site genetic studies.

Classifying episodes in schizophrenia and bipolar disorder: criteria for relapse and remission applied to recent-onset samples

Research on predicting and preventing episodes of schizophrenia and mood disorder lacks consistent, specific definitions of episodes. We present an operational system for identifying relapse, exacerbation, and remission of schizophrenia and bipolar disorder within longitudinal studies that involve repeated symptom assessments. Three major classes of episodic outcome are defined: relapse or significant exacerbation, nonrelapse, and stable, severe persisting symptoms. These major classes are further subdivided to distinguish nine categories of episodic outcome. To examine ease of use, interrater reliability, and validity, the classification system was applied to recent-onset samples of schizophrenia patients (N=77) and bipolar mood disorder patients (N=23) followed on medication for 9- to 12-month periods. A range of episodic outcomes were distinguished with high interrater reliability. Despite being prescribed continuous medication, 21% of the recent-onset schizophrenia patients and 61% of bipolar patients met criteria for relapse or significant exacerbation during this follow-up period. Predictive relationships support the validity of this system for classifying episodes. A computer program is available to facilitate its use. Use of these explicit definitions of episodes may help to clarify the relationship between episodic outcome and other fundamental domains of illness outcome, particularly other symptom dimensions, work functioning, and social functioning.

Exploring the short term visual store in schizophrenia using the attentional blink

Schizophrenia patients exhibit numerous deficits on visual processing tasks, ranging from very early stages of visual processing (e.g., backward masking) to the later working memory stages (e.g., delayed match-to-sample, N-back). However, little is known about deficits in an intermediate stage of visual information processing, namely short term visual memory (STVM). The attentional blink (AB) paradigm is considered to be a valid way to assess the STVM, and recent studies have reported AB deficits in schizophrenia. However, it is not clear whether the reported AB deficit in schizophrenia patients is due to their increased susceptibility to backward masking or increased vulnerability in the STVM. In this study we first found poorer performance in the AB task in 37 schizophrenia patients compared to 26 normal controls. To examine the effects of increasing and decreasing mask strength on AB performance in patients and controls, we next systematically varied the masking effect by varying the length of the distracters immediately following the targets. The manipulation had relatively little effect on the patient--control differences and patients continued to show an enhanced AB effect across conditions. The findings suggest that the enhanced AB effect in schizophrenia reflects an abnormality in their short term visual memory, as opposed to their enhanced susceptibility to visual masking.

Does anhedonia in schizophrenia reflect faulty memory for subjectively experienced emotions?

The authors evaluated whether self-reported trait anhedonia in schizophrenia reflects faulty memory, such that patients are capable of experiencing pleasure while engaged in enjoyable activities but underestimate their pleasure in recalling these experiences. Thirty schizophrenia patients and 31 nonpatient control participants rated their emotional responses to pleasant and neutral foods and film clips and completed a surprise recall task for their emotions after a 4-hr delay. Despite reporting elevated trait anhedonia, patients did not significantly differ from control participants in immediate pleasant emotional responses to the stimuli or in delayed recall for these experiences. In-the-moment pleasure and short-term retention for emotional experiences thus appear to be relatively intact in schizophrenia. Alternative explanations for the hedonic deficit in this disorder are discussed.

Neurocognitive and social cognitive correlates of formal thought disorder in schizophrenia patients

The neurocognitive and social cognitive correlates of two types of formal thought disorder (i.e., bizarre-idiosyncratic and concrete thinking) were examined in 47 stable outpatients with schizophrenia. Both types of thinking disturbance were related to impairments in verbal learning, intrusions in verbal memory, immediate auditory memory, sustained attention, and social schema knowledge. Distractibility during an immediate memory task was associated with more frequent bizarre verbalizations but not concreteness. Impaired verbal learning rate and intrusions in verbal memory independently contributed to the prediction of bizarre responses, whereas intrusions in verbal memory and impaired immediate memory independently contributed to concrete thinking. This pattern of findings is consistent with the view that neurocognitive and, possibly, social cognitive deficits underlie these two aspects of formal thinking disturbance in schizophrenia.

Electrophysiological analysis of error monitoring in schizophrenia

In this study, the authors sought to determine whether abnormalities exhibited by schizophrenia patients in event-related potentials associated with self-monitoring--the error-related negativity (ERN) and the correct response negativity (CRN)--persist under conditions that maximize ERN amplitude and to examine relationships between the ERN and behavior in schizophrenia. Participants performed a flanker task under 2 contingencies: one encouraging accuracy and another emphasizing speed. Compared with healthy participants, in schizophrenia patients the ERN was reduced in the accuracy condition, and the CRN was enhanced in the speed condition. The amplitude of a later ERP component, the error positivity, did not differ between groups in either task condition. Reduced self-correction and increased accuracy following errors were associated with larger ERNs in both groups. Thus, ERN generation appears to be abnormal in schizophrenia patients even under conditions demonstrated to maximize ERN amplitude; however, functional characteristics of the ERN appear to be intact.

Neurocognitive performance and functional disability in the psychosis prodrome

OBJECTIVE

This study evaluates the pattern of neuropsychological deficits and their association with clinical symptomatology and social functioning in individuals identified as ultra-high-risk (UHR) for psychosis.

METHODS

A sample of 45 UHR individuals was identified using the Structured Interview for Prodromal Syndromes (SIPS) from consecutive referrals to the Staglin Music Festival Center for the Assessment and Prevention of Prodromal States (CAPPS) at UCLA. Participants were administered a neurocognitive test battery, as well as measures of global (Strauss-Carpenter Outcome Scale) and social functioning (UCLA Social Attainment Survey).

RESULTS

Participants showed significant deficits in speed of processing, verbal learning and memory, and motor speed. Poorer verbal learning and memory performance was significantly associated with poorer social functioning, and there was a trend for poorer performance on reasoning and problem solving to be associated with poorer global functioning. Verbal memory independently predicted social functioning over and above severity of negative symptoms. Cognitive deficits were not associated with severity of clinical symptomatology.

CONCLUSIONS

Despite the absence of fully psychotic symptoms, UHR individuals experience significant cognitive deficits, particularly on tasks requiring speeded information-processing and efficient recall from memory, and these deficits appear to be associated with functional disability in a manner parallel to that observed in patients with established psychotic illness.

Social perception as a mediator of the influence of early visual processing on functional status in schizophrenia

OBJECTIVE

The potential of social cognition as a mediator of relations between neurocognition and functional status in schizophrenia has been suggested by correlational studies that link neurocognition to social cognition or link social cognition to functional status. The authors used structural equation modeling to test more directly whether one aspect of social cognition (social perception) mediates relations between basic visual perception and functional status in patients with schizophrenia.

METHOD

Seventy-five outpatients with schizophrenia were administered measures of early visual processing (computerized visual masking procedures), social perception (Half Profile of Nonverbal Sensitivity), and functional status (Role Functioning Scale).

RESULTS

Structural equation modeling supported social perception as a mediator of relations between early visual processing and functional status in schizophrenia. The mediation model indicated that early visual processing is linked to functional status through social perception, thereby supporting a significant indirect relationship. The direct relationship between early visual processing and functional status was significant in a model that did not include social perception but was not significant in the mediation model that included social perception.

CONCLUSIONS

Social cognition appears to be a key determinant of functional status in schizophrenia. Using a very basic measure of visual perception, the present study found that social perception mediates the influence of early visual processing on functional status in schizophrenia.

Forward and backward visual masking in unaffected siblings of schizophrenic patients

BACKGROUND

Visual masking tasks assess the earliest stages of visual processing. This study examined visual masking performance for forward and backward masking tasks in siblings of schizophrenic patients and healthy comparison subjects.

METHODS

A staircase method was used to ensure that unmasked target identification was equivalent across subjects to eliminate differences due to discrimination of simple perceptual inputs. Four computerized visual masking tasks were administered to 43 siblings of patients and 42 normal comparison subjects. The tasks included: 1) locating a target; 2) identifying a target with a high-energy mask; 3) identifying a target with a low-energy mask; and 4) a paracontrast/metacontrast procedure with nonoverlapping target and mask.

RESULTS

Across masking conditions, there was a significant group by forward/backward interaction, meaning that siblings showed a larger difference from control subjects in backward versus forward masking. This group difference was more pronounced in the location condition.

CONCLUSIONS

These results support the theory that visual masking procedures may be indicators of vulnerability to schizophrenia. The pattern of findings in this report (larger group differences on backward versus forward masking and on the location condition) suggests that the activity of transient visual channels may be particularly linked to vulnerability.

Do recent-onset schizophrenia patients experience a "social network crisis"?

It has been proposed that the onset of schizophrenia creates a social network crisis, resulting in a dramatic deterioration of social resources during the period immediately following a first hospitalization from essentially normal pre-hospitalization levels. To evaluate this proposal, recent onset patients (n = 89) completed comprehensive assessments that examined their social networks in the 12 months prior to first hospitalization and, in a subset of patients (n = 34), at a 15-month follow-up. Cross-sectional relationships to social functioning and symptoms were examined at both time points. Compared to existing research, at the initial assessment patients were characterized by several network disturbances, including small network size, a high proportion of family members, and highly dense interconnections among network members; these disturbances generally remained moderately to highly stable at follow-up. Smaller social networks were related to poor current and premorbid social functioning and aspects of clinical functioning, particularly at the 15-month follow-up assessment. Thus, this first repeated assessment of social network characteristics in the early course of schizophrenia does not support the social network crisis concept. Instead, results suggest that functionally relevant social network disturbances often exist by the time of first hospitalization in schizophrenia.

Event-related gamma activity in schizophrenia patients during a visual backward-masking task

OBJECTIVE

Schizophrenia patients experience deficits in many aspects of cognition and perception. Abnormalities in gamma activity may underlie some of these deficits, including rapid processing of visual stimuli. This study examined event-related gamma range activity during a visual backward-masking task in schizophrenia patients and normal comparison subjects.

METHOD

Event-related gamma activity was recorded in 15 normal comparison subjects and 32 schizophrenia patients. Participants had event-related gamma activity recorded while viewing 60 unmasked visual targets and 240 trials of visual backward masking. Effects of group, accuracy (correct versus incorrect), stimulus-onset asynchrony, and regional activity (left versus right hemisphere, anterior versus posterior regions) were assessed.

RESULTS

Schizophrenia patients had significantly reduced gamma activity in relation to comparison subjects during the backward-masking task. Normal comparison subjects showed significantly greater gamma activity in the right hemisphere, whereas schizophrenia patients did not show this pattern of lateralization. For the unmasked target, there was no group effect and no significant interactions in gamma-band responses.

CONCLUSIONS

These results extend previous findings of abnormal gamma range activity in schizophrenia patients. Patients showed overall less gamma activity and failed to show lateralization of activity to the right hemisphere during masking, but they showed comparable levels of gamma activity to unmasked stimuli. Schizophrenia patients' poorer performance during a masking task may be partly influenced by this abnormal level and the distribution of gamma activity.