Factor structure of cognition and functional capacity in two studies of schizophrenia and bipolar disorder: Implications for genomic studies

Towards Enhancing Drug Development Methodology to Treat Cognitive Impairment Associated With Schizophrenia and Other Neuropsychiatric Conditions: Insights From 2 Decades of Clinical Trials

Cognitive impairment is a core feature and leading cause of functional disability in schizophrenia and other neuropsychiatric disorders. The Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative in the early 2000s marked a pivotal moment for drug development, establishing consensus on methodology for treatment studies, including assessment strategies and trial designs, for cognitive impairment associated with schizophrenia (CIAS). Despite extensive industry-sponsored and academic drug development efforts over the last 2 decades using these strategies no pharmacological treatments have been approved for CIAS. Drawing on pharmaceutical industry experience and scientific developments since the MATRICS initiative, we review lessons learned about the practical and operational complexities of conducting large-scale CIAS clinical trials. Based on this collective experience, we identify elements of the MATRICS guidelines that may warrant reconsideration and suggest some new approaches to streamline the drug development pathway, without weakening standards for evidence. Our goal is to initiate an open exchange among all stakeholders about possible enhancements to drug development methodology that optimize our ability to develop new treatments for cognitive impairment in schizophrenia and other neuropsychiatric disorders.

Personalized Cognitive Health in Psychiatry: Current State and the Promise of Computational Methods

BACKGROUND

Decades of research have firmly established that cognitive health and cognitive treatment services are a key need for people living with psychosis. However, many current clinical programs do not address this need, despite the essential role that an individual's cognitive and social cognitive capacities play in determining their real-world functioning. Preliminary practice-based research in the Early Psychosis Intervention Network early psychosis intervention network shows that it is possible to develop and implement tools that delineate an individuals' cognitive health profile and that help engage the client and the clinician in shared decision-making and treatment planning that includes cognitive treatments. These findings signify a promising shift toward personalized cognitive health.

STUDY DESIGN

Extending upon this early progress, we review the concept of interindividual variability in cognitive domains/processes in psychosis as the basis for offering personalized treatment plans. We present evidence from studies that have used traditional neuropsychological measures as well as findings from emerging computational studies that leverage trial-by-trial behavior data to illuminate the different latent strategies that individuals employ.

STUDY RESULT

We posit that these computational techniques, when combined with traditional cognitive assessments, can enrich our understanding of individual differences in treatment needs, which in turn can guide evermore personalized interventions.

CONCLUSION

As we find clinically relevant ways to decompose maladaptive behaviors into separate latent cognitive elements captured by model parameters, the ultimate goal is to develop and implement approaches that empower clients and their clinical providers to leverage individual's existing learning capacities to improve their cognitive health and well-being.

Immediate post performance judgements about cognitive performance in schizophrenia and bipolar disorder: associations with test performance and subjective overall judgments regarding abilities

INTRODUCTION

The study explored associations between the accuracy of post assessment judgements of cognitive performance with global self-assessments of psychosocial functioning compared to evaluations generated by observers in schizophrenia and bipolar disorder.

METHODS

An abbreviated cognitive assessment based on the MATRICS Consensus Cognitive Battery was administered to 122 individuals with schizophrenia and 113 with bipolar disorder. They provided self-estimates of their performance after each subtest. In addition, self-reports on cognition, social cognition, and everyday functioning were collected and compared to observer ratings.

RESULTS

Both groups overestimated their cognitive function, but in bipolar disorder, there was 30% shared variance between task performance and self-rated task performance (vs. 5% in schizophrenia). Significant correlations were found between self-reported everyday outcomes and both actual and self-assessed performance. In schizophrenia, immediate judgements were only related to self-rated functioning, not to observer rated functioning. In bipolar disorder, impairments in self-assessment of performance correlated with observer ratings of cognitive ability, which was not observed in schizophrenia.

CONCLUSIONS

While both groups showed correlations between cognitive performance and introspective accuracy, individuals with bipolar disorder showed higher accuracy in assessing their cognitive performance and other outcomes. Notably, impairments in introspective accuracy were associated with observer-rated functioning exclusively in bipolar disorder.

Cross-diagnostic determinants of cognitive functioning: the muscarinic cholinergic receptor as a model system

Cognitive impairment is a predictor of disability across different neuropsychiatric conditions, and cognitive abilities are also strongly related to educational attainment and indices of life success in the general population. Previous attempts at drug development for cognitive enhancement have commonly attempted to remedy defects in transmitters systems putatively associated with the conditions of interest such as the glutamate system in schizophrenia. Recent studies of the genomics of cognitive performance have suggested influences that are common in the general population and in different neuropsychiatric conditions. Thus, it seems possible that transmitter systems that are implicated for cognition across neuropsychiatric conditions and the general population would be a viable treatment target. We review the scientific data on cognition and the muscarinic cholinergic receptor system (M1 and M4) across different diagnoses, in aging, and in the general population. We suggest that there is evidence suggesting potential beneficial impacts of stimulation of critical muscarinic receptors for the enhancement of cognition in a broad manner, as well as the treatment of psychotic symptoms. Recent developments make stimulation of the M1 receptor more tolerable, and we identify the potential benefits of M1 and M4 receptor stimulation as a trans-diagnostic treatment model.

Accuracy of immediate self-assessment of neurocognitive test performance: Associations with psychiatric diagnosis and longitudinal psychotic symptoms

Participants with schizophrenia (SCZ) and bipolar disorder (BD) have challenges in self-evaluation of their cognitive and functional abilities, referred to as introspective accuracy (IA). Although psychotic symptoms are commonly found to be uncorrelated with cognitive performance, many models of the development of delusions focus on failures in self-assessment and responses biases during momentary monitoring. We performed a single 4-test cognitive assessment on 240 participants (schizophrenia n = 126; bipolar disorder n = 114) and asked them to make a judgment about their performance immediately after completion of each task. We related performance and these judgments to results of Ecological Momentary Assessments (EMA) of the momentary occurrence of psychotic symptoms (Voices, paranoid ideas, other delusions) collected over up to 90 surveys over a 30 days prior to the single cognitive assessment. We examined test performance and the accuracy of self-assessment at that assessment, looking at diagnostic differences in performance and mis-estimation of performance. Participants with bipolar disorder had better cognitive performance, but there were no differences in mis-estimation. Analyses of the correlation between cognitive performance and self-assessment were all significant and better cognitive performance predicted reduced errors in self-assessment. Examination of the 30-day course of psychotic symptoms and IA could only be performed in participants with schizophrenia, revealing correlations between more common occurrences of all three psychotic symptoms and increased absolute values for IA errors. These data are consistent with theories of cognitive response biases and the formation of delusions.

Associations between symptom and neurocognitive dimensions in clinical high risk for psychosis

Introduction

Clinical high risk for psychosis (CHR) is associated with mild cognitive impairments. Symptoms are clustered into positive, negative and disorganization symptoms. The association between specific symptom dimensions and cognitive functions remains unclear. The aim of this study was to investigate the associations between cognitive functions and positive, negative, and disorganization symptoms.

Method

53 CHR subjects fulfilling criteria for attenuated psychotic syndrome in the Structural Interview for Prodromal Syndromes (SIPS) were assessed for cognitive function. Five cognitive domain z-scores were defined by contrasting with observed scores of a group of healthy controls (n = 40). Principal Components Analyses were performed to construct general cognitive composite scores; one using all subtests and one using the cognitive domains. Associations between cognitive functions and symptoms are presented as Spearman's rank correlations and partial Spearman's rank correlations adjusted for age and gender.

Results

Positive symptoms were negatively associated with executive functions and verbal memory, and disorganization symptoms with poorer verbal fluency. Negative symptoms were associated with better executive functioning. There were no significant associations between the general cognitive composites and any of the symptom domains, except for a trend for positive symptoms.

Conclusion

In line with previous research, data indicated associations between positive symptoms and poorer executive functioning. Negative symptoms may not be related to executive functions in CHR the same way as in psychosis. Our results could indicate that attenuated positive symptoms are more related to cognitive deficits in CHR than positive symptoms in schizophrenia and FEP.

Shape features of working memory-related deep-brain regions differentiate high and low community functioning in schizophrenia

We have previously shown that schizophrenia (SCZ) participants with high community functioning demonstrate better verbal working memory (vWM) performance relative to those with low community functioning. In the present study, we investigated whether neuroanatomical differences in regions supporting vWM also exist between schizophrenia groups that vary on community functioning. Utilizing magnetic resonance imaging, shape features of deep-brain nuclei known to be involved in vWM were calculated in samples of high functioning (HF-SCZ, n = 23) and low functioning schizophrenia participants (LF-SCZ, n = 18), as well as in a group of healthy control participants (CON, n = 45). Large deformation diffeomorphic metric mapping was employed to characterize surface anatomy of the caudate nucleus, globus pallidus, hippocampus, and thalamus. Statistical analyses involved linear mixed-effects models and vertex-wise contrast mapping to assess between-group differences in structural shape features, and Pearson correlations to evaluate relationships between shape metrics and vWM performance. We found significant between-group main effects in deep-brain surface anatomy across all structures. Post-hoc comparisons revealed HF-SCZ and LF-SCZ groups significantly differed on both caudate and hippocampal shape, however, significant correlations with vWM were only observed in hippocampal shape for both SCZ groups. Specifically, more abnormal hippocampal deformation was associated with lower vWM suggesting hippocampal shape is both a neural substrate for vWM deficits and a potential biomarker to predict or monitor the efficacy of cognitive rehabilitation. These findings add to a growing body of literature related to functional outcomes in schizophrenia by demonstrating unique shape patterns across the spectrum of community functioning in SCZ.

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Deep-brain abnormalities are present in patients regardless of functional severity.

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Caudate and hippocampal shape differ between community functioning-based groups.

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Verbal working memory relates to hippocampal shape in both patient groups.

Dimensionality analysis of the German version of the Screen for Cognitive Impairment in Psychiatry (SCIP-G)

Background

Psychiatric disorders, especially schizophrenia, are characterised by cognitive impairment. The rapid detection of cognitive dysfunction - also in the course of the disease - is of great importance. The Screen for Cognitive Impairment in Psychiatry (SCIP) was developed to provide screening of psychiatric patients in clinical practice and is available in several languages. Prior psychometric investigations into the dimensionality of the SCIP have produced two different models: a one-factor model assumes that the five subscales of the SCIP load together, whereas an alternative model suggests that the subscales load on two factors, namely verbal memory and processing speed. We carried out a confirmatory factor analysis of the German version of the SCIP (SCIP-G).

Methods

323 patients with psychotic, bipolar affective, and depressive disorders were studied.

Results

The one-factor approach did not yield an acceptable model fit (chi-squared test: χ² = 109.5, df = 5, p < 0.001, χ²/df = 21.9). A two-factor solution, with the subtests Verbal Learning Test-Immediate Recall, Delayed Recall Test of the VLT, and Working Memory Test loading on the first factor, whereas the subtests Verbal Fluency Test and Psychomotor Speed Test loading on the second factor, obtained a good model fit (χ² = 6.7, df = 3, p = 0.08, χ²/df = 2.2).

Conclusions

These data show that a good model fit can be achieved with a two-factor solution for the SCIP. This study is the first to conduct a confirmatory factor analysis using the German SCIP version and to test its dimensional structure using a hypothesis-testing approach.

Sexual dimorphism in the relationship between Forkhead-Box P2 and BMI with cognitive deficits in schizophrenia

FOXP2, cognitive deficits, and schizophrenia are associated with neurodegenerative pathophyisiology. Mounting evidence suggests that body mass index (BMI) and FOXP2 may contribute to cognitive deficits in schizophrenia. However, the sex difference in the contribution of FOXP2 and BMI, as well as their potential interaction with cognitive deficits in schizophrenia, have not been investigated. A total of 867 schizophrenia patients and 402 controls were recruited. Cognitive function was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The polymorphism rs10447760 of the FOXP2 gene was genotyped. Male schizophrenia patients had superior language performance compared to female patients (F = 17.83; p Bonferroni < 0.0001). BMI was positively associated with language scores in male patients with schizophrenia (ß = 0.60, t = 3.30, p = 0.001), as well as in patients with schizophrenia who carried the FOXP2 rs10447760 CC genotype (ß = 0.53, t = 3.16, p = 0.002). Interestingly, this association was only found in male patients with schizophrenia who also carried the FOXP2 rs10447760 CC genotype (ß = 0.63, t = 3.44, p = 0.001). Our study reveals a sex difference in the language deficits of schizophrenia patients and shows sexual dimorphism in the contribution of FOXP2, BMI, and their interaction to cognitive deficits in patients with schizophrenia.

Assessment of Negative Symptoms in Clinical Trials of Acute Schizophrenia: Test of a Novel Enrichment Strategy

Drug trials for negative symptoms in schizophrenia select patients based on the severity and stability of negative symptoms, using criteria that are not suitable for trials of acute exacerbation of schizophrenia. Here we present a method to prognostically enrich subjects having a predefined factor structure in PANSS and apply it to the measurement of negative symptoms specifically in trials of acute schizophrenia. A vector of 1335 elements based on between- and within-item variances, covariances, and differences of PANSS items was created to calculate an index of heterogeneity and to enrich for a predetermined symptom construct in PANSS. Using prerandomization PANSS scores across N = 4876 subjects in 13 trials of acute schizophrenia, we demonstrate an ability to select for a subpopulation having the greatest amount of variance explained across the 7-items of the Marder PANSS negative symptom (MPNS) construct. Network analyses on subjects enriched for MPNS construct confirm that negative symptoms were most influential in overall psychopathology, distinct from subjects without the MPNS construct. As expected for D2 antagonists, drug-placebo differences on negative symptoms with lurasidone were not specific to the subpopulation having the MPNS construct. In contrast, the novel TAAR1 agonist ulotaront demonstrated specific improvements in negative symptoms which were greatest in the MPNS subpopulation. These results demonstrate the utility of a novel prognostic enrichment strategy that can address heterogeneity in clinical trials, where patients can be selected on the basis of a greater likelihood of having the measured symptom construct (negative symptoms) related to the disorder (schizophrenia). ClinicalTrials.gov Identifiers: NCT0296938, NCT00088634, NCT00549718, NCT00615433, NCT00790192.

Neurocognition and social cognition in patients with schizophrenia spectrum disorders with and without a history of violence: results of a multinational European study

OBJECTIVE

Neurocognitive impairment has been extensively studied in people with schizophrenia spectrum disorders and seems to be one of the major determinants of functional outcome in this clinical population. Data exploring the link between neuropsychological deficits and the risk of violence in schizophrenia has been more inconsistent. In this study, we analyse the differential predictive potential of neurocognition and social cognition to discriminate patients with schizophrenia spectrum disorders with and without a history of severe violence.

METHODS

Overall, 398 (221 cases and 177 controls) patients were recruited in forensic and general psychiatric settings across five European countries and assessed using a standardized battery.

RESULTS

Education and processing speed were the strongest discriminators between forensic and non-forensic patients, followed by emotion recognition. In particular, increased accuracy for anger recognition was the most distinctive feature of the forensic group.

CONCLUSIONS

These results may have important clinical implications, suggesting potential enhancements of the assessment and treatment of patients with schizophrenia spectrum disorders with a history of violence, who may benefit from consideration of socio-cognitive skills commonly neglected in ordinary clinical practice.

A Systematic Review of Cognition-Brain Morphology Relationships on the Schizophrenia-Bipolar Disorder Spectrum

The nature of the relationship between cognition and brain morphology in schizophrenia-spectrum disorders (SSD) and bipolar disorder (BD) is uncertain. This review aimed to address this, by providing a comprehensive systematic investigation of links between several cognitive domains and brain volume, cortical thickness, and cortical surface area in SSD and BD patients across early and established illness stages. An initial search of PubMed and Scopus databases resulted in 1486 articles, of which 124 met inclusion criteria and were reviewed in detail. The majority of studies focused on SSD, while those of BD were scarce. Replicated evidence for specific regions associated with indices of cognition was minimal, however for several cognitive domains, the frontal and temporal regions were broadly implicated across both recent-onset and established SSD, and to a lesser extent BD. Collectively, the findings of this review emphasize the significance of both frontal and temporal regions for some domains of cognition in SSD, while highlighting the need for future BD-related studies on this topic.

Performance-based assessment of social skills in a large sample of participants with schizophrenia, bipolar disorder and healthy controls: Correlates of social competence and social appropriateness

INTRODUCTION

Performance-based assessments of social skills have detected impairments in people with severe mental illness and are correlated with functional outcomes in people with schizophrenia and bipolar disorder. The most common of these assessments, the Social Skills Performance Assessment (SSPA), has two communication scenarios and items measuring both social competence and appropriateness. As real-world competence and appropriateness appear to have different correlates, we hypothesized that SSPA Items measuring competence and appropriateness would be distinct and have different correlations with other outcomes.

METHODS

We aggregated data from 557 people with schizophrenia, 106 with bipolar disorder, and 378 well controls from 4 separate research studies. All participants were assessed with both SSPA scenarios and other performance based and clinician-rated measures. A single expert rated the SSPA interactions for competence and appropriateness while blind to participant diagnoses.

RESULTS

Participants with bipolar disorder and schizophrenia performed more poorly on every item of the SSPA than healthy controls. Items measuring social competence and appropriateness in communication were intercorrelated across scenarios, as were elements of socially competent communication, although the items measuring competence did not correlate substantially with appropriateness. Items assessing social competence, but not social appropriateness, correlated with better cognitive and functional performance and residential and financial independence.

DISCUSSION

Social competence and social appropriateness were distinct elements of performance-based social skills with potential differences in their functional correlates. As both social competence and appropriateness impact functional outcomes, improvement in the measurement and treatment of appropriate communication seems to be an important goal.

Cooperative Studies Program (CSP) #572: A Study of Serious Mental Illness in Veterans as a Pathway to personalized medicine in Schizophrenia and Bipolar Illness

BACKGROUND

Personalization of psychiatric treatment includes treatment of symptoms, cognition and functional deficits, suicide, and medical co-morbidities. VA Collaborative Study 572 examined a large sample of male and female veterans with schizophrenia (n=3,942) and with bipolar disorder (n=5,414) with phenotyping and genomic analyses. We present the results to date and future directions.

METHODS

All veterans received a structured diagnostic interview and assessments of suicidal ideation and behavior, PTSD, and health. Veterans with schizophrenia were assessed for negative symptoms and lifetime depression. All were assessed with a cognitive and functional capacity assessment. Data for genome wide association studies were collected. Controls came from the VA Million Veteran Program.

RESULTS

Suicidal ideation or behavior was present in 66%. Cognitive and functional deficits were consistent with previous studies. 40% of the veterans with schizophrenia had a lifetime major depressive episode and PTSD was present in over 30%. Polygenic risk score (PRS) analyses indicated that cognitive and functional deficits overlapped with PRS for cognition, education, and intelligence in the general population and PRS for suicidal ideation and behavior correlated with previous PRS for depression and suicidal ideation and behavior, as did the PRS for PTSD.

DISCUSSION

Results to date provide directions for personalization of treatment in SMI, veterans with SMI, and veterans in general. The results of the genomic analyses suggest that cognitive deficits in SMI may be associated with general population features. Upcoming genomic analyses will reexamine the issues above, as well as genomic factors associated with smoking, substance abuse, negative symptoms, and treatment response.

Is There Evidence That Stimulus Parameters and Electrode Placement Affect the Cognitive Side Effects of Electroconvulsive Therapy in Patients With Schizophrenia and Schizoaffective Disorder?: A Systematic Review

ABSTRACT

Seventy percent of patients with treatment-resistant schizophrenia do not respond to clozapine. Electroconvulsive therapy (ECT) can potentially offer significant benefit in clozapine-resistant patients. However, cognitive side effects can occur with ECT and are a function of stimulus parameters and electrode placements. Thus, the objective of this article is to systematically review published clinical trials related to the effect of ECT stimulus parameters and electrode placements on cognitive side effects. We performed a systematic review of the literature up to July of 2020 for clinical studies published in English or German examining the effect of ECT stimulus parameters and/or electrode placement on cognitive side effects in patients with schizophrenia or schizoaffective disorder. The literature search generated 3 randomized, double-blind, clinical trials, 1 randomized, nonblinded trial, and 1 retrospective study. There are mixed findings regarding whether pulse width and stimulus dose impact on cognitive side effects. One study showed less cognitive side effect for right unilateral (RUL) than bitemporal (BT) electrode placement, and 2 studies showed a cognitive advantage for bifrontal (BF) compared with BT ECT. Only 1 retrospective study measured global cognition and showed post-ECT cognitive improvement with all treatment modalities using Montreal Cognitive Assessment in comparison to pre-ECT Montreal Cognitive Assessment scores. Current data are limited, but evolving. The evidence suggests that RUL or BF ECT have more favorable cognitive outcomes than BT ECT. Definitive larger clinical trials are needed to optimize parameter and electrode placement selection to minimize adverse cognitive effects.

Evidence for avolition in bipolar disorder? A 30-day ecological momentary assessment comparison of daily activities in bipolar disorder and schizophrenia

OBJECTIVES

Disability is common in bipolar disorder (BD) and predicted by persistent sadness. We used ecological momentary assessment (EMA) to examine daily activities in people with BD and schizophrenia. We classified activities as productive, unproductive, or passive recreation, relating them to momentary sadness, location, and social context.

METHODS

71 people with BD and 102 people with schizophrenia were sampled 3 times/day for 30 days with an EMA survey. Each survey asked where they were, with whom, what they were doing, and if they were sad.

RESULTS

People with BD were home more than 50% of the time. There were no differences in prevalence of activity types across diagnoses. People with BD were less likely to report only one activity since the prior survey, but the most surveys still reported only one. For both groups, sadness and being home and alone since the last survey was associated with less productive activity and more passive recreation.

CONCLUSIONS

Participants with BD and schizophrenia manifested high levels of unproductive and passive activities, predicted by momentary sadness. These activity patterns are consistent with descriptions of avolition and they minimally differentiated people with BD and schizophrenia. Previous reports of negative symptoms in BD may have been identifying these behaviors.

The Computerized Functional Skills Assessment and Training Program: Sensitivity to Global Cognitive Impairment, Correlations With Cognitive Abilities, and Factor Structure

OBJECTIVES

We evaluated a novel computer-based functional skills assessment and training (CFSAT) program, which includes ecologically valid simulations of six everyday technology-related tasks. In this report, we describe the psychometric properties of the assessment in terms of sensitivity to impairment, factor structure and correlations with cognitive performance.

DESIGN

Cross-sectional baseline assessment prior to a treatment study.

PARTICIPANTS

Noncognitively impaired older adults (n = 62) and cognitively impaired older adults (n = 55), that ranged in age from 60 to 86 years (M = 73.12), was primarily female (90%), and ethnically diverse (21% Hispanic, 52% African American). Participants were divided at baseline on the basis of MOCA scores and cognitive complaints.

MEASUREMENTS

The Brief Assessment of Cognition (BAC), app version, was used to measure cognitive performance and completion times on the six subtasks of the CFAST constituted the functional capacity measures.

RESULTS

Performance on the CFSAT and BAC discriminated the two cognitive status groups. All of the cognitive domains on the BAC correlated significantly with all six CFSAT subtasks (all p < .01). Factor analyses suggested that the CFSAT and the BAC loaded on separate factors and regression analyses indicated that executive functioning and processing speed had the largest independent association with performance on the CFSAT.

CONCLUSION

The CFSAT is sensitive to functional impairments seen in cognitively impaired older adults. Cognitive performance and CFSAT scores were related but nonredundant. Thus, the CFSAT appears to identify functional deficits that could be targeted with skills training interventions, likely augmented by pharmacological or computerized cognitive training interventions.

Major Neuropsychological Impairments in Schizophrenia Patients: Clinical Implications

PURPOSE OF REVIEW

Schizophrenia is a complex severe mental illness with high morbidity and mortality. It is characterized by positive symptoms, negative symptoms, and cognitive impairment. Cognitive impairment is strongly associated with functional impairment and presents a major barrier to recovery. This article reviews some of the most recent research on cognition in schizophrenia and the clinical implications.

RECENT FINDINGS

There have been recent studies related to the genomics of cognition and neural structures involved in cognition. We review recent investigations into the assessment of social cognition and the implications of impaired introspective accuracy. A recent network analysis assessed the relationship of neurocognition and social cognition to functional capacity. We further discuss the role of specific symptoms in functioning, including negative symptoms and symptoms related to autism spectrum disorder. We conclude with a discussion of a novel computerized treatment for social cognition. Recent research has sought to better understand several dimensions of cognition including genomics, brain structure, social cognition, functional capacity, and symptomatology. This recent research brings us closer to understanding the complex clinical picture of schizophrenia and the best treatments to achieve recovery.

Factor structure of cognitive performance and functional capacity in schizophrenia: Evidence for differences across functional capacity measures

BACKGROUND

Cognition and functional capacity predict functional outcomes in mental illness. Traditional approaches conceptualize cognition as comprised of domains, but many studies support a unifactorial structure. Some functional capacity measures may share a single-factor structure with cognition. In this study, we examined the factor structure of two measures of functional capacity, a conventional assessment and a newer computerized assessment, testing for a shared factor structure with cognition.

METHODS

Patients with schizophrenia and healthy controls were examined with the MATRICS Consensus Cognitive Battery (MCCB), the UCSD Performance Based Skills Assessment (UPSA), and the Virtual Reality Functional Capacity Assessment Tool (VRFCAT). Models of the factor structures of the MCCB, UPSA, and VRFCAT were calculated, as were correlations between MCCB scores and individual VRFCAT objectives.

RESULTS

The MCCB, VRFCAT, and UPSA all had unifactorial structures. The best fitting model of the correlations between MCCB and UPSA was a shared single factor, while the best fit for the relationship between MCCB and VRFCAT had two factors. Correlations between the MCCB domain and composite scores and the VRFCAT objectives suggested global rather than specific patterns of correlation.

DISCUSSION

The relationship between cognitive performance and functional capacity was found to vary across functional capacity assessments. The UPSA and MCCB were not differentiated into separate factors, suggesting that the UPSA may overlap with neurocognitive performance. However, the VRFCAT appears to measure functional abilities that are separable from, yet correlated with, neurocognitive performance. It may provide a more distinctive assessment of the functional capacity construct.

Neuropsychology of Bipolar Disorder

Bipolar disorder is associated with significant dysfunction in a broad range of neuropsychological domains and processes. Deficits have been reported to occur in symptomatic states (depression, [hypo]mania) as well as in remission (euthymia), having consequences for psychological well-being and social and occupational functioning. The profile and magnitude of neuropsychological deficits in bipolar disorder have been explored in a number of systematic reviews and meta-analyses. After discussing these briefly, this chapter will focus on examining the clinical and demographic factors that influence and modify the pattern and magnitude of deficits, as well as reviewing methods of assessment and analysis approaches which may improve our understanding of these problems.

Domains of cognition and their assessment

Cognitive performance is typically conceptualized in terms of domains of functioning. These domains are hierarchical in nature, with the bottom referring to more basic sensory and perceptual processes and the top referring to elements of executive functioning and cognitive control. Domains are not independent of each other and executive functioning exerts control over the utilization of more basic processes. Assessments are typically targeted at subdomains of each ability area and careful combination of tasks can reveal patterns of performance consistent with a variety of different neurological and neuropsychiatric conditions. This review covers the general structures of domains, the patterns of impairments across domains seen in common neuropsychiatric conditions, and use of assessment strategies to differentiate, to the extent possible, between different types of conditions manifesting cognitive impairment.


Suicidal ideation, behavior, and mortality in male and female US veterans with severe mental illness

BACKGROUND

We compared male and female American veterans with schizophrenia or bipolar disorder regarding clinical characteristics associated with lifetime suicidal ideation and behavior. Subsequent mortality, including death by suicide, was also assessed.

METHODS

Data from questionnaires and face-to-face evaluations were collected during 2011-2014 from 8,049 male and 1,290 female veterans with schizophrenia or bipolar disorder. In addition to comparing male-female characteristics, Cox regression models-adjusted for demographic information, medical-psychiatric comorbidities, and self-reported suicidal ideation and behavior-were used to examine gender differences in associations of putative risk factors with suicide-specific and all-cause mortality during up to six years of follow-up.

RESULTS

Women overall were younger, more likely to report a history of suicidal behavior, less likely to be substance abusers, and had lower overall mortality during follow-up. Among women only, psychiatric comorbidity was paradoxically associated with lower all-cause mortality (hazard ratio [HR]=0.53, 95% CI, 0.29-0.96, p = 0.037 for 1 disorder vs. none; HR=0.44, 95% CI, 0.25-0.77, p = 0.004 for ≥2 disorders vs. none). Suicide-specific mortality involved relatively few events, but crude rates were an order of magnitude higher than in the U.S. general and overall veteran populations.

LIMITATIONS

Incomplete cause-of-death information and low statistical power for male-female comparisons regarding mortality.

CONCLUSIONS

Female veterans with SMI differed from females in the general population by having a higher risk of suicide attempts. They also had more lifetime suicide attempts than male veterans with same diagnoses. These differences should inform public policy and clinical planning.

Cognitive validation of cross-diagnostic cognitive subgroups on the schizophrenia-bipolar spectrum

BACKGROUND

Cognitive heterogeneity in schizophrenia spectrum disorders (SSD) and bipolar disorder (BD) has been explored using clustering analyses. However, the resulting subgroups have not been cognitively validated beyond measures used as clustering variables themselves. We compared the emergent cross-diagnostic subgroups of SSD and BD patients on measures used to classify them, and also across a range of alternative cognitive measures assessing some of the same constructs.

METHOD

Domain scores from the Matrics Consensus Cognitive Battery were used in a cross-diagnostic clustering analysis of 86 patients with SSD (n = 45) and BD (n = 41). The emergent subgroups were then compared to each other and healthy controls (n = 76) on these and alternative measures of these domains, as well as on premorbid IQ, global cognition and a proxy of cognitive decline.

RESULTS

A three-cluster solution was most appropriate, with subgroups labelled as Globally Impaired, Selectively Impaired, and Superior/Near-Normal relative to controls. With the exception of processing speed performance, the subgroups were generally differentiated on the cognitive domain scores used as clustering variables. Differences in cognitive performance among these subgroups were not always statistically significant when compared on the alternative cognitive measures. There was evidence of global cognitive impairment and putative cognitive decline in the two cognitively impaired subgroups.

LIMITATIONS

For clustering analysis, sample size was relatively small.

CONCLUSIONS

The overall pattern of findings tentatively suggest that emergent cross-diagnostic cognitive subgroups are not artefacts of the measures used to define them, but may represent the outcome of different cognitive trajectories.

Genome-wide association study of cognitive performance in U.S. veterans with schizophrenia or bipolar disorder

Cognitive impairment is a frequent and serious problem in patients with various forms of severe mental illnesses (SMI), including schizophrenia (SZ) and bipolar disorder (BP). Recent research suggests genetic links to several cognitive phenotypes in both SMI and in the general population. Our goal in this study was to identify potential genomic signatures of cognitive functioning in veterans with severe mental illness and compare them to previous findings for cognition across different populations. Veterans Affairs (VA) Cooperative Studies Program (CSP) Study #572 evaluated cognitive and functional capacity measures among SZ and BP patients. In conjunction with the VA Million Veteran Program, 3,959 European American (1,095 SZ, 2,864 BP) and 2,601 African American (1,095 SZ, 2,864 BP) patients were genotyped using a custom Affymetrix Axiom Biobank array. We performed a genome-wide association study of global cognitive functioning, constructed polygenic scores for SZ and cognition in the general population, and examined genetic correlations with 2,626 UK Biobank traits. Although no single locus attained genome-wide significance, observed allelic effects were strongly consistent with previous studies. We observed robust associations between global cognitive functioning and polygenic scores for cognitive performance, intelligence, and SZ risk. We also identified significant genetic correlations with several cognition-related traits in UK Biobank. In a diverse cohort of U.S. veterans with SZ or BP, we demonstrate broad overlap of common genetic effects on cognition in the general population, and find that greater polygenic loading for SZ risk is associated with poorer cognitive performance.

Neuregulin 3 rs10748842 polymorphism contributes to the effect of body mass index on cognitive impairment in patients with schizophrenia

There is evidence that obesity or higher body mass index is correlated with cognitive impairment in schizophrenia. Recent studies have demonstrated that genetic risk factors, such as the NRG3, are correlated with both elevated BMI and reduced cognitive function. In present study, we aimed to determine whether possession of the NRG3 rs10748842 influences the correlation between elevated BMI and reduced cognitive ability in schizophrenia. To our knowledge, this has never been examined before. A total of 625 inpatients with schizophrenia and 400 controls were recruited. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was performed to assess cognitive function. We used multiple analysis of covariance (MANCOVA), analyses of covariance (ANCOVA), Pearson correlations, partial correlations, and multivariate regression analysis to test the influence of NRG3 rs10748842 on the aforementioned variables. All RBANS five sub-scores and total score were lower in patients than those in controls (all p < 0.001). Patients carrying NRG3 rs10748842 TC + CC heterozygous genotype had lower attention score compared to TT homozygous genotype (adjusted F = 4.77, p = 0.029). BMI was positively associated with language score in patients (β = 0.387, t = 2.59, p = 0.01). Interestingly, we further found positive association between BMI and language score in TT carriers (partial correlations: r = 0.13, adjusted p = 0.004; multivariate regression: β = 0.42, t = 2.66, p = 0.008), but not in CT + CC carrier (p > 0.05). Our study demonstrated that NRG3 rs10748842 was associated with cognitive impairments, especially attention performance in schizophrenia. Moreover, NRG3 rs10748842 altered the effect of BMI on cognitive impairments as measured by the RBANS language score in chronic patients with schizophrenia.

NRG3 contributes to cognitive deficits in chronic patients with schizophrenia

BACKGROUND

Cognitive deficit is a fundamental trait of schizophrenia, but its mecwhanisms remain unknown. The neuregulin 3 (NRG3) gene, involving in neuronal function, has been considered to be associated with schizophrenia and cognition. However, no study has investigated the effects of NRG3 polymorphism on cognitive deficits in a large sample of the patients with schizophrenia.

METHODS

A total of 1112 schizophrenia patients and 423 controls were recruited and genotyped with NRG3 rs10748842. Among them, 864 patients and 403 controls were assessed for cognition through the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). SHEsis was applied and followed by logistic regression analysis. The models of analyses of covariance (ANCOVA) were constructed to examine the effects of NRG3 rs10748842 on cognitive deficits.

RESULTS

No differences in NRG3 rs10748842 allele and genotype were found between patients and controls (both p > 0.05). With the exception of Visuospatial/construction, the other RBANS scores were significantly lower in patients compared to controls after adjusting for gender and education (all p < 0.001). Interestingly, we found that NRG3 rs10748842 was associated with cognitive deficit in schizophrenia, showing that patients carrying C allele had lower attention and total scores than those with TT genotype (both p < 0.05).

CONCLUSION

NRG3 rs10748842 may not confer susceptibility to schizophrenia, but may be more closely associated with cognitive deficit, especially attention performance in chronic schizophrenia.

The role of genetics in cognitive remediation in schizophrenia: A systematic review

The role of genetics in cognitive remediation therapies in schizophrenia has not been completely understood yet. Different genes involved in neurotrophic, dopaminergic and serotonin systems have reported to influence cognitive functioning in schizophrenia. These genetic factors could also be contributing to the variability in responsiveness to cognitive treatments. No comprehensive synthesis of the literature of the role of genetics in the context of cognitive remediation has been conducted until now. We aimed to systematically review the published works through three electronic database searches: PubMed, Scopus, and the Cochrane Library. Eligible studies revealed a rising interest in the field although the number of published studies was rather small (n = 10). Eventually, promising results showing a relationship between some phenotypic variations based on different polymorphisms and different levels of responsivity to cognitive remediation therapies have been described although results are still inconclusive. In case those findings will be replicated, they could be guiding future research and informing clinical decision-making in the next future.

Neurocognitive heterogeneity in young offspring of patients with bipolar disorder: The effect of putative clinical stages

BACKGROUND

Bipolar disorder (BD) is associated with significant cognitive heterogeneity. In recent years, a number of studies have investigated cognitive subgroups in BD using data-driven methods and found that BD includes several subgroups including a severely impaired and a neurocognitively intact cluster. Studies in offspring of BD (BDoff) are particularly important to establish the timing of emergence of cognitive subgroups but studies investigating cognitive heterogeneity in BDoff are lacking. Our aim was to investigate cognitive heterogeneity in BDoff and the relationship between cognitive heterogeneity and putative clinical stages of BD.

METHODS

Seventy-one euthymic BDoff and 50 healthy controls were assessed using clinical measures and a battery of neuropsychological tests. Neurocognitive subgroups were investigated using latent class analysis.

RESULTS

Three neurocognitive subgroups, including a severe impairment group, a good performance cluster, and a subgroup characterized by intermediate/selective impairment was found. Both severe and intermediate level impairment subgroups underperformed healthy controls in processing speed, verbal fluency, visual memory and working memory. Deficits in verbal memory and executive functions were only evident in severe impairment subgroup. The putative stage of the illness had no significant effect on cognitive clustering of BDoff. Trait impulsivity scores were significantly increased in severe and intermediate impairment clusters but not in the cognitively good functioning subgroup of BDoff.

LIMITATIONS

The cross-sectional nature of the study was the main consideration.

CONCLUSION

These results suggest that cognitive heterogeneity is premorbid characteristic of BD and cognitive subgroups of BDoff emerge prior to the onset of illness and prodromal symptoms.

Brain structure, cognition, and brain age in schizophrenia, bipolar disorder, and healthy controls

Schizophrenia and bipolar disorder (BD) may be disorders of accelerated aging. Direct comparison of healthy aging populations with schizophrenia and BD patients across the adult lifespan may help inform this theory. In total, 225 individuals (91 healthy controls, 81 schizophrenia, 53 euthymic BD) underwent 3T T1-weighted magnetic resonance imaging, diffusion tensor imaging, and cognitive testing. We analyzed associations among age, diagnosis, and cognition with cortical thickness and fractional anisotropy (FA) using general linear models. We then assessed "brain age" using a random forest algorithm, which was also assessed in an independent sample (n = 147). Participants with schizophrenia had lower cortical thickness and FA compared with the other two groups, most prominently in fronto-temporal circuitry. These brain changes were more evident in younger participants than in older ones, yet were associated with cognitive performance independent of diagnosis. Predicted age was 8 years greater than chronological age in individuals with schizophrenia in the first sample and 6 years greater in the second sample. Predicted and chronological age were not different in BD. Differences in brain circuitry are present from illness onset most prominently in schizophrenia and to a lesser extent in BD. These results support a non-progressive "early hit" hypothesis/etiology of illness in the major psychoses. Brain age differences support the hypothesized early aging mechanism in schizophrenia but not in BD.

Controversies in Computerized Cognitive Training

Computerized cognitive training (CCT) to improve cognitive functioning is of enormous interest and has been applied in a broad range of populations with goals of improving both cognition and community functioning. Recent reviews presenting negative conclusions about CCT efficacy have inconsistent definitions of the treatment targets and cognitive improvement. They do not present an accurate representation of the typical process of CCT and cognitive remediation (CR), especially as delivered in major mental illnesses such as schizophrenia. This review provides guidance on the definitions of CCT and CR, the uses of CCT and CR, and the definitions and measurements of cognitive and functional gains. The review focuses on schizophrenia and healthy aging, with each population receiving unique CCT or CR approaches and substantial extant literature with which to elucidate fundamental CCT and CR concepts and research findings. It is our conclusion that CCT has been shown in most studies to improve cognitive performance on untrained tests in healthy older people and in people with schizophrenia. Functional gains in schizophrenia appear to be limited to CR studies. Clearly defining CCT, CR, and levels of treatment-related gains will be critical for understanding the benefits of these widely used treatment programs.

Symptom dimensions and subgroups in childhood-onset schizophrenia

OBJECTIVE

This study investigated symptom dimensions and subgroups in the National Institute of Mental Health (NIMH) childhood-onset schizophrenia (COS) cohort and their similarities to adult-onset schizophrenia (AOS) literature.

METHOD

Scores from the Scales for the Assessment of Positive and Negative Symptoms (SAPS & SANS) from 125 COS patients were assessed for fit with previously established symptom dimensions from AOS literature using confirmatory factor analysis (CFA). K-means cluster analysis of each individual's scores on the best fitting set of dimensions was used to form patient clusters, which were then compared using demographic and clinical data.

RESULTS

CFA showed the SAPS & SANS data was well suited to a 2-dimension solution, including positive and negative dimensions, out of five well established models. Cluster analysis identified three patient groups characterized by different dimension scores: (1) low scores on both dimensions, (2) high negative, low positive scores, and (3) high scores on both dimensions. These groups had different Full scale IQ, Children's Global Assessment Scale (CGAS) scores, ages of onset, and prevalence of some co-morbid behavior disorders (all p<3.57E-03).

CONCLUSION

Our analysis found distinct symptom-based subgroups within the NIMH COS cohort using an established AOS symptom structure. These findings confirm the heterogeneity of COS and were generally consistent with AOS literature.

Neuropsychological predictors of performance-based measures of functional capacity and social skills in individuals with severe mental illness

Neuropsychological abilities may underlie successful performance of everyday functioning and social skills. We aimed to determine the strongest neuropsychological predictors of performance-based functional capacity and social skills performance across the spectrum of severe mental illness (SMI). Unemployed outpatients with SMI (schizophrenia, bipolar disorder, or major depression; n = 151) were administered neuropsychological (expanded MATRICS Consensus Cognitive Battery), functional capacity (UCSD Performance-Based Skills Assessment-Brief; UPSA-B), and social skills (Social Skills Performance Assessment; SSPA) assessments. Bivariate correlations between neuropsychological performance and UPSA-B and SSPA total scores showed that most neuropsychological tests were significantly associated with each performance-based measure. Forward entry stepwise regression analyses were conducted entering education, diagnosis, symptom severity, and neuropsychological performance as predictors of functional capacity and social skills. Diagnosis, working memory, sustained attention, and category and letter fluency emerged as significant predictors of functional capacity, in a model that explained 43% of the variance. Negative symptoms, sustained attention, and letter fluency were significant predictors of social skill performance, in a model explaining 35% of the variance. Functional capacity is positively associated with neuropsychological functioning, but diagnosis remains strongly influential, with mood disorder participants outperforming those with psychosis. Social skill performance appears to be positively associated with sustained attention and verbal fluency regardless of diagnosis; however, negative symptom severity strongly predicts social skills performance. Improving neuropsychological functioning may improve psychosocial functioning in people with SMI.

Suicidal ideation and behavior in US veterans with schizophrenia or bipolar disorder

OBJECTIVE

Using data from a Department of Veterans Affairs study of schizophrenia (SZ) and bipolar I disorder (BP), we evaluated lifetime risks for suicidal ideation and behavior. We were interested in the prevalence and correlates of these outcomes, in populations of patients with severe mental illness (SMI), who have not been compared directly in previous studies despite data on high risk in each group separately.

METHOD

Data were collected on demographic factors, medical and psychiatric comorbidity, cognitive and functional status, and lifetime suicidal ideation or behavior in a study of veterans with SZ (N = 3942) or BP (N = 5414). In-person diagnosis and evaluation, including performance-based assessments of cognition and functional skills, make this study unique compared to studies of completed suicide. Multinomial logistic regression examined how risk factors, including major depression and negative symptoms in SCZ patients, correlated with ideation and behavior.

RESULTS

A lifetime history of suicidal ideation or behavior was reported by a majority of Veterans with SZ (69.9%) or BP (82.3%). Lower risk was found for patients with SZ vs. BP (odds ratio [OR] = 0.82 for ideation; OR = 0.81 for behavior). The highest risk was found for patients with multiple psychiatric comorbidities (OR = 2.61 for ideation; OR = 3.82 for behavior). Clinical factors (e.g., psychiatric comorbidity) contributed more of the variance in the predictive model than demographic factors.

CONCLUSIONS

A history of suicidal ideation or behavior is common among US Veterans with SZ or BP, and specific demographic and clinical attributes correlate with variation in risk. These findings underscore the need for continuous monitoring for suicidal ideation and behavior in veteran populations with SMI, as well as the development of better risk predictions, including genomic factors. Although PTSD is a major current focus in veteran populations, the large number of veterans with SZ or BP and their high suicide risk suggests a greater clinical focus may be warranted.

Characterizing cognitive heterogeneity on the schizophrenia-bipolar disorder spectrum

BACKGROUND

Current group-average analysis suggests quantitative but not qualitative cognitive differences between schizophrenia (SZ) and bipolar disorder (BD). There is increasing recognition that cognitive within-group heterogeneity exists in both disorders, but it remains unclear as to whether between-group comparisons of performance in cognitive subgroups emerging from within each of these nosological categories uphold group-average findings. We addressed this by identifying cognitive subgroups in large samples of SZ and BD patients independently, and comparing their cognitive profiles. The utility of a cross-diagnostic clustering approach to understanding cognitive heterogeneity in these patients was also explored.

METHOD

Hierarchical clustering analyses were conducted using cognitive data from 1541 participants (SZ n = 564, BD n = 402, healthy control n = 575).

RESULTS

Three qualitatively and quantitatively similar clusters emerged within each clinical group: a severely impaired cluster, a mild-moderately impaired cluster and a relatively intact cognitive cluster. A cross-diagnostic clustering solution also resulted in three subgroups and was superior in reducing cognitive heterogeneity compared with disorder clustering independently.

CONCLUSIONS

Quantitative SZ-BD cognitive differences commonly seen using group averages did not hold when cognitive heterogeneity was factored into our sample. Members of each corresponding subgroup, irrespective of diagnosis, might be manifesting the outcome of differences in shared cognitive risk factors.