Measuring specific, rather than generalized, cognitive deficits and maximizing between-group effect size in studies of cognition and cognitive change

A critical review of hot executive functioning in youth attention-deficit/hyperactivity disorder: Methodological limitations, conceptual considerations, and future directions

Hot executive functioning (EF) - EF under emotionally or motivationally salient conditions - is a putative etiology of attention-deficit/hyperactivity disorder (ADHD), disruptive behavior problems (DBPs), and their related impairments. Despite two decades of research, the present study is the first review of the construct in youth ADHD, with a particular focus on the role of task design, age, and DBPs, as well as relevant conceptual and methodological considerations. While certain hot EF tasks have been investigated extensively (e.g., choice impulsivity), substantial inconsistency in measurement of the broader construct remains, severely limiting conclusions. Future research should a) consider the extent to which various hot EF tasks relate to one another, a higher order factor, and other related constructs; b) further investigate task design, particularly the elicitation of emotion or motivation and its anticipated effect on EF; and c) incorporate multiple levels of analysis to validate similarities and differences among tasks with regard to the affective experiences and cognitive demands they elicit. With improved measurement and conceptual clarity, hot EF has potential to advance the literature on etiological pathways to ADHD, DBPs and associated impairments and, more broadly, may represent a useful tool for understanding the influence of emotion and motivation on cognition.

Executive function in methamphetamine users with and without psychosis

Methamphetamine abuse is associated with cognitive deficits across a wide range of domains. It is unclear, however, whether methamphetamine-dependent individuals with co-occurring psychosis are more impaired than those without psychosis on tests assessing executive function. We therefore aimed to compare the executive function performance of three groups: methamphetamine-dependent individuals with methamphetamine-induced psychosis (MA+; n = 20), methamphetamine-dependent individuals without psychosis (MA-; n = 19), and healthy controls (HC; n = 20). All participants were administered a neuropsychological test battery that assessed executive functioning across six sub domains (problem solving, working memory, verbal generativity, inhibition, set switching, and decision making). Analyses of covariance (controlling for between-group differences in IQ) detected significant between-group differences on tests assessing verbal generativity and inhibition, with MA+ participants performing significantly more poorly than HC. The finding that methamphetamine-induced psychosis is associated with performance impairments in particular subdomains of executive function may have implications for treatment adherence and relapse prevention.

The Imbalanced Plasticity Hypothesis of Schizophrenia-Related Psychosis: A Predictive Perspective

A considerable number of studies have attempted to account for the psychotic aspects of schizophrenia in terms of the influential predictive coding (PC) hypothesis. We argue that the prediction-oriented perspective on schizophrenia-related psychosis may benefit from a mechanistic model that: 1) gives due weight to the extent to which alterations in short- and long-term synaptic plasticity determine the degree and the direction of the functional disruption that occurs in psychosis; and 2) addresses the distinction between the two central syndromes of psychosis in schizophrenia: disorganization and reality-distortion. To accomplish these goals, we propose the Imbalanced Plasticity Hypothesis - IPH, and demonstrate that it: 1) accounts for commonalities and differences between disorganization and reality distortion in terms of excessive (hyper) or insufficient (hypo) neuroplasticity, respectively; 2) provides distinct predictions in the cognitive and electrophysiological domains; and 3) is able to reconcile conflicting PC-oriented accounts of psychosis.

Predicting Attention-Shaping Response in People With Schizophrenia

ABSTRACT

People with schizophrenia often experience attentional impairments that hinder learning during psychological interventions. Attention shaping is a behavioral technique that improves attentiveness in this population. Because reinforcement learning (RL) is thought to be the mechanism by which attention shaping operates, we investigated if preshaping RL performance predicted level of response to attention shaping in people with schizophrenia. Contrary to hypotheses, a steeper attentiveness growth curve was predicted by less intact pretreatment RL ability and lower baseline attentiveness, accounting for 59% of the variance. Moreover, baseline attentiveness accounted for over 13 times more variance in response to attention shaping than did RL ability. Results suggest attention shaping is most effective for lower-functioning patients, and those high in RL ability may already be close to ceiling in terms of their response to reinforcers. Attention shaping may not be a primarily RL-driven intervention, and other mechanisms of its effects should be considered.

Multisensory Integration of Emotion in Schizophrenic Patients

Multisensory integration (MSI) of emotion has been increasingly recognized as an essential element of schizophrenic patients' impairments, leading to the breakdown of their interpersonal functioning. The present review provides an updated synopsis of schizophrenics' MSI abilities in emotion processing by examining relevant behavioral and neurological research. Existing behavioral studies have adopted well-established experimental paradigms to investigate how participants understand multisensory emotion stimuli, and interpret their reciprocal interactions. Yet it remains controversial with regard to congruence-induced facilitation effects, modality dominance effects, and generalized vs specific impairment hypotheses. Such inconsistencies are likely due to differences and variations in experimental manipulations, participants' clinical symptomatology, and cognitive abilities. Recent electrophysiological and neuroimaging research has revealed aberrant indices in event-related potential (ERP) and brain activation patterns, further suggesting impaired temporal processing and dysfunctional brain regions, connectivity and circuities at different stages of MSI in emotion processing. The limitations of existing studies and implications for future MSI work are discussed in light of research designs and techniques, study samples and stimuli, and clinical applications.

Development and Evaluation of a Visual Remediation Intervention for People with Schizophrenia

It is now well documented that schizophrenia is associated with impairments in visual processing at all levels of vision, and that these disturbances are related to deficits in multiple higher-level cognitive and social cognitive functions. Visual remediation methods have been slow to appear in the literature as a potential treatment strategy to target these impairments, however, in contrast to interventions that aim to improve auditory and higher cognitive functions in schizophrenia. In this report, we describe a National Institute of Mental Health (NIMH)-funded R61/R33 grant that uses a phased approach to optimize and evaluate a novel visual remediation intervention for people with schizophrenia. The goals of this project are: (1) in the R61 phase, to establish the optimal components and dose (number of sessions) of a visual remediation intervention from among two specific visual training strategies (and their combination) for improving low and mid-level visual functions in schizophrenia; and (2) in the R33 phase, to determine the extent to which the optimal intervention improves not only visual processing but also higher-level cognitive and role functions. Here we present the scientific background for and innovation of the study, along with our methods, hypotheses, and preliminary data. The results of this study will help determine the utility of this novel intervention approach for targeting visual perceptual, cognitive, and functional impairments in schizophrenia.

The influence of impaired processing speed on cognition in first-episode antipsychotic-naïve schizophrenic patients

Background:

Impaired cognition is a prominent feature of schizophrenia. To what extent the heterogeneous cognitive impairments can be accounted for by considering only a single underlying impairment or a small number of core impairments remains elusive. This study examined whether cognitive impairments in antipsychotic-naïve, first-episode schizophrenia patients may be determined by a relative slower speed of information processing.

Method:

Forty-eight antipsychotic-naïve patients with first-episode schizophrenia and 48 matched healthy controls were administered a comprehensive battery of neuropsychological tests to assess domains of cognitive impairments in schizophrenia. Composite scores were calculated, grouping tests into cognitive domains.

Results:

There were significant differences between patients and healthy controls on global cognition and all cognitive domains, including verbal intelligence, processing speed, sustained attention, working memory, reasoning and problem solving, verbal learning and memory, visual learning and memory, and reaction time. All these significant differences, except for verbal intelligence and global cognition, disappeared when processing speed was included as a covariate.

Conclusion:

At the first stage of illness, antipsychotic-naïve patients with schizophrenia display moderate/severe impairments in all the cognitive domains assessed. The results support the contention of a global cognitive dysfunction in schizophrenia that to some extent may be determined by impaired processing speed.

Visual impairments in type 1 bipolar disorder

Objectives: The present study evaluated early visual processing, in terms of the contrast sensitivity function (CSF), in bipolar disorder (BPD) patients.Methods: Data were recorded in 17 healthy participants and 17 outpatients with type 1 BPD, from 20 to 45 years of age. The CSF was measured at spatial frequencies of 0.2, 0.6, 3.1, 8.0, 16.0 and 20.0 cycles per degree (cpd) using Gabor patches and a two-alternative, forced-choice, logarithmic staircase method. The groups were matched for gender, age and level of education.Results: The CSF differed between groups. Patients with BPD had lower discrimination at spatial frequencies of 0.2 cpd (P < 0.001), 0.6 cpd (P < 0.001), 16.0 cpd (P < 0.001) and 20.0 cpd (P < 0.001) compared with healthy subjects. No differences were observed at 3.1 cpd (P > 0.05) and 8.0 cpd (P > 0.05). This visual impairment was related both to longer duration of illness and to greater severity of manic symptoms.Conclusions: The differences in visual processing were pronounced in patients with BPD, which justifies further investigations of the pathophysiological mechanisms that are involved in sensorial alterations.

Theoretical Modeling of Cognitive Dysfunction in Schizophrenia by Means of Errors and Corresponding Brain Networks

The current evidence of cognitive disturbances and brain alterations in schizophrenia does not provide the plausible explanation of the underlying mechanisms. Neuropsychological studies outlined the cognitive profile of patients with schizophrenia, that embodied the substantial disturbances in perceptual and motor processes, spatial functions, verbal and non-verbal memory, processing speed and executive functioning. Standardized scoring in the majority of the neurocognitive tests renders the index scores or the achievement indicating the severity of the cognitive impairment rather than the actual performance by means of errors. At the same time, the quantitative evaluation may lead to the situation when two patients with the same index score of the particular cognitive test, demonstrate qualitatively different performances. This may support the view why test paradigms that habitually incorporate different cognitive variables associate weakly, reflecting an ambiguity in the interpretation of noted cognitive constructs. With minor exceptions, cognitive functions are not attributed to the localized activity but eventuate from the coordinated activity in the generally dispersed brain networks. Functional neuroimaging has progressively explored the connectivity in the brain networks in the absence of the specific task and during the task processing. The spatio-temporal fluctuations of the activity of the brain areas detected in the resting state and being highly reproducible in numerous studies, resemble the activation and communication patterns during the task performance. Relatedly, the activation in the specific brain regions oftentimes is attributed to a number of cognitive processes. Given the complex organization of the cognitive functions, it becomes crucial to designate the roles of the brain networks in relation to the specific cognitive functions. One possible approach is to identify the commonalities of the deficits across the number of cognitive tests or, common errors in the various tests and identify their common "denominators" in the brain networks. The qualitative characterization of cognitive performance might be beneficial in addressing diffuse cognitive alterations presumably caused by the dysconnectivity of the distributed brain networks. Therefore, in the review, we use this approach in the description of standardized tests in the scope of potential errors in patients with schizophrenia with a subsequent reference to the brain networks.

Normal development of context processing using the AXCPT paradigm

Context processing involves a flexible and continually updated representation of task relevant information and is a core aspect of cognitive control. The expectancy AX Continuous Performance Test (AXCPT) was designed to specifically measure context processing and has been widely applied to elucidate mechanisms of cognitive control and their impairments in conditions such as aging and schizophrenia. Here we present a large-sample, cross-sectional study of context processing aimed at characterizing its normal development from childhood to early adulthood (8 to 22 years old). We track the age-related changes in the standard AXCPT performance measures and also investigate their validity using detailed data-driven method. We show how critical maturational changes in context processing can be validly tracked from mid-adolescence onward with increasing reliance on preparatory, proactive strategies well into early adulthood. However, the early maturation from childhood into adolescence showed a sharp, two-fold discontinuity: while standard measures provide partially conflicting results suggesting an early worsening of proactive strategies, further analyses do not support their validity during this period. Our findings advocate the existence of multiple preparatory strategies that cannot be captured by indices that assume a simple dichotomy of proactive vs. reactive strategies. When evaluating context processing differences over development or in clinical populations, we advocate the explicit testing of the assumptions underlying standard AXCPT indices through complementary data-driven methods.

Psychophysical assessment of koniocellular pathway in patients with schizophrenia versus healthy controls

This study was designed to perform psychophysical assessment of koniocellular pathway in patients with schizophrenia versus healthy controls. A total of 26 patients diagnosed with schizophrenia and 15 healthy controls were included. Snellen Visual Acuity Chart scores and Short Wavelength Automated Perimetry (SWAP) visual field testing including global visual field indices [mean deviation (MD), pattern standard deviation (PSD), test time (min)], reliability parameters [false negative responses (%), false positive responses (%) and fixed losses (%)] and average threshold sensitivity [central (parafovea), peripheral area, and four quadrants] were recorded in both groups. Significantly lower MD scores, higher PSD scores and lower average threshold sensitivity at each location across the visual field were noted in schizophrenia relative to control group. In conclusion, our findings revealed a deficit in koniocellular pathway with impaired SWAP global indices and lower threshold sensitivity at each location across the visual field among chronic schizophrenic patients as compared with control subjects. Our findings emphasize potential application of SWAP outside its original intended purpose as a glaucoma test, to provide deeper understanding of the specific contribution of lateral geniculate nucleus to the visual and cognitive disturbances of schizophrenia.

Emotional intelligence in non-psychotic first-degree relatives of people with schizophrenia

Subtle social cognitive deficits in unaffected relatives of schizophrenia patients have received increasing attention over the last few years, supporting their potential endophenotypic role for this disorder. The current study assessed non-psychotic first-degree relatives' performance on a multidimensional measure of emotional intelligence (EI): the Mayer-Salovey-Caruso Emotional Intelligence Test 2.0 (MSCEIT). Endorsed by the National Institute of Mental Health, the MSCEIT is a valid and reliable instrument for detecting emotion-processing deficits among schizophrenia patients and people high in schizotypy.

METHOD

Thirty-seven first-degree relatives, 37 schizophrenia outpatients and 37 healthy controls completed the MSCEIT, which comprises eight subscales aimed to assess the four branches of EI: Identifying, Facilitating, Understanding and Managing Emotions. Potential associations with cognitive function and schizotypy levels, measured with the Schizotypal Personality Questionnaire-Brief, were further evaluated.

RESULTS

Relatives had significantly lower MSCEIT total scores than controls and also significantly lower scores on the Identifying emotions branch. Nevertheless, schizophrenia patients still had the poorest global EI performance. The strongest positive correlations were found in relatives and controls with measures of executive function, processing speed and general intelligence. A higher level of schizotypy correlated significantly with lower MSCEIT scores among controls, but not among relatives.

CONCLUSIONS

Contrary to expectations in the general population, the current study observed subtle EI impairment in non-psychotic first-degree relatives of schizophrenia patients. These findings support the hypothesis that these EI deficiencies may be potential endophenotypes located between the clinical phenotype and the genetic predisposition for schizophrenia.

Factor structure of the ARIC-NCS Neuropsychological Battery: An evaluation of invariance across vascular factors and demographic characteristics

Neuropsychological test batteries are designed to assess cognition in detail by measuring cognitive performance in multiple domains. This study examines the factor structure of tests from the ARIC-NCS battery overall and across informative subgroups defined by demographic and vascular risk factors in a population of older adults. We analyzed neuropsychological test scores from 6,413 participants in the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS) examined in 2011-2013. Confirmatory factor analysis (CFA) was used to assess the fit of an a priori hypothesized 3-domain model, and fit statistics were calculated and compared to 1- and 2-domain models. Additionally, we tested for stability (invariance) of factor structures among different subgroups defined by diabetes, hypertension, age, sex, race, and education. Mean age of participants was 76 years, 76% were White, and 60% were female. CFA on the a priori hypothesized 3-domain structure, including memory, sustained attention and processing speed, and language, fit the data better (comparative fit index [CFI] = 0.973, root mean square error of approximation [RMSEA] = 0.059) than the 2-domain (CFI = 0.960, RMSEA = 0.070) and 1-domain (CFI = 0.947, RMSEA = 0.080) models. Bayesian information criterion value was lowest, and quantile-quantile plots indicated better fit, for the 3-domain model. Additionally, multiple-group CFA supported a common structure across the tested demographic subgroups, and indicated strict invariance by diabetes and hypertension status. In this community-based population of older adults with varying levels of cognitive performance, the a priori hypothesized 3-domain structure fit the data well. The identified factors were configurally invariant by age, sex, race, and education, and strictly invariant by diabetes and hypertension status. (PsycINFO Database Record

Comparison of visual perceptual organization in schizophrenia and body dysmorphic disorder

People with schizophrenia are impaired at organizing potentially ambiguous visual information into well-formed shape and object representations. This perceptual organization (PO) impairment has not been found in other psychiatric disorders. However, recent data on body dysmorphic disorder (BDD), suggest that BDD may also be characterized by reduced PO. Similarities between these groups could have implications for understanding the RDoC dimension of visual perception in psychopathology, and for modeling symptom formation across these two conditions. We compared patients with SCZ (n=24) to those with BDD (n=20), as well as control groups of obsessive-compulsive disorder (OCD) patients (n=20) and healthy controls (n=20), on two measures of PO that have been reliably associated with schizophrenia-related performance impairment. On both the contour integration and Ebbinghaus illusion tests, only the SCZ group demonstrated abnormal performance relative to controls; the BDD group performed similarly to the OCD and CON groups. In addition, on both tasks, the SCZ group performed more abnormally than the BDD group. Overall, these data suggest that PO reductions observed in SCZ are not present in BDD. Visual processing impairments in BDD may arise instead from other perceptual disturbances or attentional biases related to emotional factors.

Cortical contributions to impaired contour integration in schizophrenia

OBJECTIVES

Visual perceptual organization impairments in schizophrenia (SCZ) are well established, but their neurobiological bases are not. The current study used the previously validated Jittered Orientation Visual Integration (JOVI) task, along with fMRI, to examine the neural basis of contour integration (CI), and its impairment in SCZ. CI is an aspect of perceptual organization in which multiple distinct oriented elements are grouped into a single continuous boundary or shape.

METHODS

On the JOVI, five levels of orientational jitter were added to non-contiguous closed contour elements embedded in background noise to progressively increase the difficulty in perceiving contour elements as left- or right-pointing ovals. Multi-site fMRI data were analyzed for 56 healthy control subjects and 47 people with SCZ.

RESULTS

SCZ patients demonstrated poorer CI, and this was associated with increased activation in regions involved in global shape processing and visual attention, namely the lateral occipital complex and superior parietal lobules. There were no brain regions where controls demonstrated more activation than patients.

CONCLUSIONS

CI impairment in this sample of outpatients with SCZ was related to excessive activation in regions associated with object processing and allocation of visual-spatial attention. There was no evidence for basic impairments in contour element linking in the fMRI data. The latter may be limited to poor outcome patients, where more extensive structural and functional changes in the occipital lobe have been observed.

Hierarchical Classes Analysis (HICLAS): A novel data reduction method to examine associations between biallelic SNPs and perceptual organization phenotypes in schizophrenia

The power of SNP association studies to detect valid relationships with clinical phenotypes in schizophrenia is largely limited by the number of SNPs selected and non-specificity of phenotypes. To address this, we first assessed performance on two visual perceptual organization tasks designed to avoid many generalized deficit confounds, Kanizsa shape perception and contour integration, in a schizophrenia patient sample. Then, to reduce the total number of candidate SNPs analyzed in association with perceptual organization phenotypes, we employed a two-stage strategy: first a priori SNPs from three candidate genes were selected (GAD1, NRG1 and DTNBP1); then a Hierarchical Classes Analysis (HICLAS) was performed to reduce the total number of SNPs, based on statistically related SNP clusters. HICLAS reduced the total number of candidate SNPs for subsequent phenotype association analyses from 6 to 3. MANCOVAs indicated that rs10503929 and rs1978340 were associated with the Kanizsa shape perception filling in metric but not the global shape detection metric. rs10503929 was also associated with altered contour integration performance. SNPs not selected by the HICLAS model were unrelated to perceptual phenotype indices. While the contribution of candidate SNPs to perceptual impairments requires further clarification, this study reports the first application of HICLAS as a hypothesis-independent mathematical method for SNP data reduction. HICLAS may be useful for future larger scale genotype-phenotype association studies.

Windows to the soul: vision science as a tool for studying biological mechanisms of information processing deficits in schizophrenia

Cognitive and information processing deficits are core features and important sources of disability in schizophrenia. Our understanding of the neural substrates of these deficits remains incomplete, in large part because the complexity of impairments in schizophrenia makes the identification of specific deficits very challenging. Vision science presents unique opportunities in this regard: many years of basic research have led to detailed characterization of relationships between structure and function in the early visual system and have produced sophisticated methods to quantify visual perception and characterize its neural substrates. We present a selective review of research that illustrates the opportunities for discovery provided by visual studies in schizophrenia. We highlight work that has been particularly effective in applying vision science methods to identify specific neural abnormalities underlying information processing deficits in schizophrenia. In addition, we describe studies that have utilized psychophysical experimental designs that mitigate generalized deficit confounds, thereby revealing specific visual impairments in schizophrenia. These studies contribute to accumulating evidence that early visual cortex is a useful experimental system for the study of local cortical circuit abnormalities in schizophrenia. The high degree of similarity across neocortical areas of neuronal subtypes and their patterns of connectivity suggests that insights obtained from the study of early visual cortex may be applicable to other brain regions. We conclude with a discussion of future studies that combine vision science and neuroimaging methods. These studies have the potential to address pressing questions in schizophrenia, including the dissociation of local circuit deficits vs. impairments in feedback modulation by cognitive processes such as spatial attention and working memory, and the relative contributions of glutamatergic and GABAergic deficits.

Contribution of coherent motion to the perception of biological motion among persons with Schizophrenia

People with schizophrenia (SCZ) are impaired in several domains of visual processing, including the discrimination and detection of biological motion. However, the mechanisms underlying SCZ-related biological motion processing deficits are unknown. Moreover, whether these impairments are specific to biological motion or represent a more widespread visual motion processing deficit is unclear. In the current study, three experiments were conducted to investigate the contribution of global coherent motion processing to biological motion perception among patients with SCZ. In Experiments 1 and 2, participants with SCZ (n = 33) and healthy controls (n = 33) were asked to discriminate the direction of motion from upright and inverted point-light walkers in the presence and absence of a noise mask. Additionally, participants discriminated the direction of non-biological global coherent motion. In Experiment 3, participants discriminated the direction of motion from upright scrambled walkers (which contained only local motion information) and upright random position walkers (which contained only global form information). Consistent with previous research, results from Experiment 1 and 2 showed that people with SCZ exhibited deficits in the direction discrimination of point-light walkers; however, this impairment was accounted for by decreased performance in the coherent motion control task. Furthermore, results from Experiment 3 demonstrated similar performance in the discrimination of scrambled and random position point-light walkers.

Effects of short-term inpatient treatment on sensitivity to a size contrast illusion in first-episode psychosis and multiple-episode schizophrenia

INTRODUCTION

In the Ebbinghaus illusion, a shape appears larger than its actual size when surrounded by small shapes and smaller than its actual size when surrounded by large shapes. Resistance to this visual illusion has been previously reported in schizophrenia, and linked to disorganized symptoms and poorer prognosis in cross-sectional studies. It is unclear, however, when in the course of illness this resistance first emerges or how it varies longitudinally with illness phase.

METHOD

We addressed these issues by having first-episode psychosis patients, multiple-episode schizophrenia patients and healthy controls complete a psychophysical task at two different time points, corresponding to hospital admission and discharge for patients. The task required judging the relative size of two circular targets centered on either side of the screen. Targets were presented without context (baseline), or were surrounded by shapes that made the size judgment harder or easier (misleading and helpful contexts, respectively). Context sensitivity was operationalized as the amount of improvement relative to baseline in the helpful condition minus the amount of decrement relative to baseline in the misleading condition.

RESULTS

At hospital admission, context sensitivity was lower in the multiple-episode group than in the other groups, and was marginally less in the first episode than in the control group. In addition, schizophrenia patients were significantly more and less accurate than the other groups in the misleading and helpful conditions, respectively. At discharge, all groups exhibited similar context sensitivity. In general, poorer context sensitivity was related to higher levels of disorganized symptoms, and lower level of depression, excitement, and positive symptoms.

DISCUSSION

Resistance to the Ebbinghaus illusion, as a characteristic of the acute phase of illness in schizophrenia, increases in magnitude after the first episode of psychosis. This suggests that visual context processing is a state-marker in schizophrenia and a biomarker of relapse and recovery.

Has the generalized deficit become the generalized criticism?

The "generalized cognitive deficit problem" refers to a situation in which a generalized deficit gives the false appearance of a specific deficit due to the psychometric properties of tests, and it is an important methodological consideration in schizophrenia research. However, it also generates considerable confusion and is often used indiscriminately as a scientific criticism, even in situations to which it does not apply. Further, the generalized deficit problem creates few concerns in interpretation for many central questions in contemporary schizophrenia research. The research literature has shifted away from the traditional goal of identifying generalized vs differential deficits, and the field now demonstrates (1) increased recognition that a generalized deficit, broadly defined, probably does not exist in schizophrenia, (2) increased emphasis on explaining both shared and unique variance across measures to understand the mechanisms through which cognition relates to external variables (eg, functional outcome), and (3) increased use of neuroscientific methods to explore cognition in schizophrenia in which the structure and richness of data can be used to minimize misinterpretation of the sort that can occur when using only behavioral measures. Clearly, consideration of the generalized deficit still remains essential in certain experimental contexts, but criticisms based on this concern are unwarranted in many other situations in schizophrenia research. This commentary is intended to help clarify the distinctions between these 2 situations so that concerns will be expressed in a more selective, less reflexive, manner.

The clinical translation of a measure of gain control: the contrast-contrast effect task

The goal of the current project was to further develop a measure of gain control--the Contrast-Contrast Effect (CCE)--for use in clinical studies of schizophrenia. The CCE is based on an illusion in which presenting a medium contrast patch surrounded by a high-contrast patch induces individuals to perceive that center patch as having lower contrast than when the patch is presented in isolation. Thus, in the CCE, impaired gain control should lead to more accurate perceptions of the center patch. We tested 132 individuals with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, schizophrenia or schizoaffective disorder and 130 demographically similar healthy controls. The results indicated that the CCE effect can be obtained with standard equipment, simplified scoring, and a short interstimulus interval (100 ms), revealing a robust suppression of perceived contrast of the center patch when surrounded by a high-contrast annulus. Furthermore, we found a significant reduction in the effect of the high-contrast surround among individuals with schizophrenia, though the effect size was smaller than original reported by Dakin. However, when we eliminated subjects who performed poorly on "catch" trials that controlled for off-task performance, the reduced surround effect among patients was no longer significant in the main analyses. Importantly, this suggests that at least part of the reduced surround effect (if not all) in schizophrenia could be attributable to impaired attentional mechanisms that contribute to off-task performance. Additional analyses suggested that the length of the task could be shortened without losing power to detect surround effects in healthy individuals.

Report from the working group conference on multisite trial design for cognitive remediation in schizophrenia

The National Institute of Mental Health (NIMH)-Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Project and related efforts have stimulated the initiation of several studies of pharmacologic treatments for cognitive impairment in schizophrenia. Cognitive remediation may provide an excellent platform for the provision of new learning opportunities and the acquisition of new skills for patients who are engaged in pharmacologic trials to improve cognition. However, it is not clear how a cognitive remediation intervention would be employed in multisite clinical trials. A meeting of experts on cognitive remediation and related methodological topics was convened to address the feasibility and study design issues for the development of a multisite trial of cognitive remediation in schizophrenia called the Cognitive Remediation in the Schizophrenia Trials Network study. This report details the findings from this meeting, which included the following 4 conclusions. (1) A multisite trial of a cognitive remediation intervention using a network of diverse research sites would be of great scientific value. (2) Various interventions could be employed for this multisite trial. (3) Programs that do not address key motivational and interpersonal aspects of cognitive remediation may benefit from supplementation with "bridging groups" that allows patients to meet with others and to apply their newly acquired cognitive skills to everyday life. (4) Before a multisite efficacy trial is initiated, a pilot study could demonstrate the feasibility of conducting a trial using a cognitive remediation intervention.

Increased fusiform area activation in schizophrenia during processing of spatial frequency-degraded faces, as revealed by fMRI

BACKGROUND

People with schizophrenia demonstrate perceptual organization impairments, and these are thought to contribute to their face processing difficulties.

METHOD

We examined the neural substrates of emotionally neutral face processing in schizophrenia by investigating neural activity under three stimulus conditions: faces characterized by the full spectrum of spatial frequencies, faces with low spatial frequency information removed [high spatial frequency (HSF) condition], and faces with high spatial frequency information removed [low spatial frequency (LSF) condition]. Face perception in the HSF condition is more reliant on local feature processing whereas perception in the LSF condition requires greater reliance on global form processing. Past studies of perceptual organization in schizophrenia indicate that patients perform relatively more poorly with degraded stimuli but also that, when global information is absent, patients may perform better than controls because of their relatively increased ability to initially process individual features. Therefore, we hypothesized that people with schizophrenia (n=14) would demonstrate greater face processing difficulties than controls (n=13) in the LSF condition, whereas they would demonstrate a smaller difference or superior performance in the HSF condition.

RESULTS

In a gender-discrimination task, behavioral data indicated high levels of accuracy for both groups, with a trend toward an interaction involving higher patient performance in the HSF condition and poorer patient performance in the LSF condition. Patients demonstrated greater activity in the fusiform gyrus compared to controls in both degraded conditions.

CONCLUSIONS

These data suggest that impairments in basic integration abilities may be compensated for by relatively increased activity in this region.

Limitations of true score variance to measure discriminating power: psychometric simulation study

Demonstrating a specific cognitive deficit usually involves comparing patients' performance on 2 or more tests. The psychometric confound occurs if the psychometric properties of these tests lead patients to show greater cognitive deficits in 1 domain. One way to avoid the psychometric confound is to use tests with a similar level of discriminating power, which is a test's ability to index true individual differences in classic psychometric theory. One suggested way to measure discriminating power is to calculate true score variance (L. J. Chapman & J. P. Chapman, 1978). Despite the centrality of these formulations, there is no systematic examination of the relationship between the observable property of true score variance and the latent property of discriminating power. The authors simulated administrations of free response tests and forced choice tests by creating different replicable ability scores for 2 groups, across a wide range of various psychometric properties (i.e., difficulty, reliability, observed variance, and number of items), and computing an ideal index of discriminating power. Simulation results indicated that true score variance had only limited ability to predict discriminating power (explained about 10% of variance in replicable ability scores). Furthermore, the ability varied across tests with wide ranges of psychometric variables, such as difficulty, observed variance, reliability, and number of items. Discriminating power depends on a complicated interaction of psychometric properties that is not well estimated solely by a test's true score variance.

Functional significance of preserved affect recognition in schizophrenia

Affect recognition (AR) is a core component of social information processing; thus, it may be critical to understanding social behavior and functioning in broader aspects of daily living. Deficits in AR are well documented in schizophrenia, but there is also evidence that many individuals with schizophrenia perform AR tasks at near-normal levels. In the current study, we sought to evaluate the functional significance of AR deficits in schizophrenia by comparing subgroups with normal-range and impaired AR performance on proxy and interviewer-rated measures of real-world functioning. Schizophrenia outpatients were classified as normal-range (N=17) and impaired (N=31) based on a logistic cut point in the sample distribution of Bell-Lysaker Emotion Recognition Task (BLERT) scores, referenced to a normative sample of healthy control subjects (N=56). The derived schizophrenia subgroups were then compared on proxy [University of California San Diego Performance-Based Skill Assessment (UPSA), Social Skills Performance Assessment (SSPA), Medication Management Ability Assessment (MMAA)] and interviewer-rated [Quality of Life Scale (QLS), Independent Living Skills Survey (ILSS)] measures of functioning, as well as a battery of neurocognitive tests. Initial analyses indicated superior MMAA and QLS performance in the near-normal AR subgroup. Covariate analyses indicated that group differences in neurocognition fully mediated the observed associations between AR and MMAA, and attenuated the observed relationships between AR classification and QLS. These results support three main conclusions. First, AR, like many other domains of psychopathology studied in schizophrenia, is preserved in select subgroups. Second, there is a positive relationship between AR performance and functional outcome measures. Third, neurocognition appears to mediate the relationship between AR and measures of functioning.

Metacognition in schizophrenia: processes underlying patients' reflections on their own episodic memory

BACKGROUND

The aim of the study was to explore the processes underlying schizophrenia patients' reflections on their own memory. Cognitive deficits and insight problems are considered core symptoms of schizophrenia. Even when people fail to recall a solicited target, they can provide feeling of knowing (FOK) judgments that reflect their ability to judge the accessibility of the target in memory. The metamemory approach allows for direct and experimental quantification of the correspondence between the subjective judgments and the objective measures of memory performance. According to the accessibility hypothesis, FOK evaluations rely on the accessibility of partial and/or contextual information relevant to the memory target.

METHODS

The accessibility of partial information relating to a memory target was investigated in 21 patients and 21 healthy comparison subjects matched for age, gender, and level of education. The material to be learned consisted of four-letter nonsense tetragrams, with each letter providing partial information about the four-letter target.

RESULTS

The results show that despite memory recall (p < .01) and recognition impairments (p = .02) and lower FOK ratings (p < .05), patients' metamemory judgments increased linearly with the amount of partial information recalled (from one letter to four letters, p < .01). The products of memory retrieval were predictive of both their FOK judgments and their subsequent memory performance.

CONCLUSIONS

Schizophrenia patients are as capable as comparison subjects of relying on the products of memory retrieval to monitor accurately their awareness of what they do or do not know. The finding may be of interest for cognitive remediation.

An fMRI examination of visual integration in schizophrenia

Behavioral and electrophysiological studies of schizophrenia have consistently demonstrated impairments in the integration of visual features into unified perceptual representations. Specific brain regions involved in this dysfunction, however, remain to be clarified. This study used functional Magnetic Resonance Imaging (fMRI) to examine the relative involvement of visual cortex areas (involved in form perception) and parietal and frontal regions (involved in attention), in the visual integration impairment in schizophrenia. Fourteen patients with schizophrenia and 14 healthy controls were compared on behavioral performance and data acquired via fMRI while completing a contour integration task that had previously been used to identify a visual integration deficit in schizophrenia. The schizophrenia patients demonstrated poorer visual integration than controls. Analyses of peak signal change indicated that while the groups were equivalent in area V1, the schizophrenia group demonstrated reduced signal in areas V2-V4, which are the earliest regions sensitive to global configurations of stimuli. Moreover, whereas the control group demonstrated greater recruitment of prefrontal and parietal areas during perception of integrated forms compared to random stimuli, the schizophrenia group demonstrated greater recruitment of frontal regions during perception of random stimuli. The two groups differed on brain regions involved in form perception even when they were matched on accuracy levels. The visual integration disturbance in schizophrenia involves both deficient basic visual processes (beginning as early as occipital region V2), as well as reduced feedback from visual attention regions that normally serves to amplify relevant visual representations relative to irrelevant information.

Construct validity: advances in theory and methodology

Measures of psychological constructs are validated by testing whether they relate to measures of other constructs as specified by theory. Each test of relations between measures reflects on the validity of both the measures and the theory driving the test. Construct validation concerns the simultaneous process of measure and theory validation. In this article, we review the recent history of validation efforts in clinical psychological science that has led to this perspective, and we review the following recent advances in validation theory and methodology of importance for clinical researchers. These are: the emergence of nonjustificationist philosophy of science; an increasing appreciation for theory and the need for informative tests of construct validity; valid construct representation in experimental psychopathology; the need to avoid representing multidimensional constructs with a single score; and the emergence of effective new statistical tools for the evaluation of convergent and discriminant validity.

Cognitive remediation for schizophrenia: it is even more complicated

PURPOSE OF REVIEW

Attempts to remediate the cognitive difficulties of people with a diagnosis of schizophrenia have shown efficacy; however, existing treatment studies display huge variation, frustrating efforts to determine how best to apply this treatment tool. This review summarizes findings of induced cognitive change in schizophrenia, with reference to the remediation method, the presence of accompanying treatment(s), how cognitive change generalizes and its value.

RECENT FINDINGS

Although there is strong evidence that cognitive change can be induced in schizophrenia, there is little evidence for the superiority of any treatment approach. Furthermore, remediation is most effective when in combination with other treatments, such as vocational training. Cognitive rehabilitation can be cost-effective and is valued by patients. A number of studies show generalization of positive outcomes beyond cognitive variables, with more focused treatment associated with less generalization.

SUMMARY

Induced cognitive change does not necessarily need to be large to facilitate functional outcomes. Instead, opportunities to apply newly acquired cognitive skills and strategies in the real world are vital. The next generation of studies need to compare different treatments using specific and more general measures of cognitive outcome. These may then throw light on their mechanisms of action. The results of these more sophisticated studies will allow therapists to tailor treatments to individuals to maximize gain for patients.

CNTRICS final task selection: working memory

The third meeting of the Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) was focused on selecting promising measures for each of the cognitive constructs selected in the first CNTRICS meeting. In the domain of working memory, the 2 constructs of interest were goal maintenance and interference control. CNTRICS received 3 task nominations for each of these constructs, and the breakout group for working memory evaluated the degree to which each of these tasks met prespecified criteria. For goal maintenance, the breakout group for working memory recommended the AX-Continuous Performance Task/Dot Pattern Expectancy task for translation for use in clinical trial contexts in schizophrenia research. For interference control, the breakout group recommended the recent probes and operation/symmetry span tasks for translation for use in clinical trials. This article describes the ways in which each of these tasks met the criteria used by the breakout group to recommend tasks for further development.

Selecting paradigms from cognitive neuroscience for translation into use in clinical trials: proceedings of the third CNTRICS meeting

This overview describes the goals and objectives of the third conference conducted as part of the Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) initiative. This third conference was focused on selecting specific paradigms from cognitive neuroscience that measured the constructs identified in the first CNTRICS meeting, with the goal of facilitating the translation of these paradigms into use in clinical trials contexts. To identify such paradigms, we had an open nomination process in which the field was asked to nominate potentially relevant paradigms and to provide information on several domains relevant to selecting the most promising tasks for each construct (eg, construct validity, neural bases, psychometrics, availability of animal models). Our goal was to identify 1-2 promising tasks for each of the 11 constructs identified at the first CNTRICS meeting. In this overview article, we describe the on-line survey used to generate nominations for promising tasks, the criteria that were used to select the tasks, the rationale behind the criteria, and the ways in which breakout groups worked together to identify the most promising tasks from among those nominated. This article serves as an introduction to the set of 6 articles included in this special issue that provide information about the specific tasks discussed and selected for the constructs from each of 6 broad domains (working memory, executive control, attention, long-term memory, perception, and social cognition).