Generalized and specific neurocognitive deficits in psychotic disorders: utility for evaluating pharmacological treatment effects and as intermediate phenotypes for gene discovery

Integrating Clinical Neuropsychology and Psychotic Spectrum Disorders: A Systematic Analysis of Cognitive Dynamics, Interventions, and Underlying Mechanisms

Background and Objectives: The study aims to provide a comprehensive neuropsychological analysis of psychotic spectrum disorders, including schizophrenia, bipolar disorder, and depression. It focuses on the critical aspects of cognitive impairments, diagnostic tools, intervention efficacy, and the roles of genetic and environmental factors in these disorders. The paper emphasizes the diagnostic significance of neuropsychological tests in identifying cognitive deficiencies and their predictive value in the early management of psychosis. Materials and Methods: The study involved a systematic literature review following the PRISMA guidelines. The search was conducted in significant databases like Scopus, PsycINFO, PubMed, and Web of Science using keywords relevant to clinical neuropsychology and psychotic spectrum disorders. The inclusion criteria required articles to be in English, published between 2018 and 2023, and pertinent to clinical neuropsychology's application in these disorders. A total of 153 articles were identified, with 44 ultimately included for detailed analysis based on relevance and publication status after screening. Results: The review highlights several key findings, including the diagnostic and prognostic significance of mismatch negativity, neuroprogressive trajectories, cortical thinning in familial high-risk individuals, and distinct illness trajectories within psychosis subgroups. The studies evaluated underline the role of neuropsychological tests in diagnosing psychiatric disorders and emphasize early detection and the effectiveness of intervention strategies based on cognitive and neurobiological markers. Conclusions: The systematic review underscores the importance of investigating the neuropsychological components of psychotic spectrum disorders. It identifies significant cognitive impairments in attention, memory, and executive function, correlating with structural and functional brain abnormalities. The paper stresses the need for precise diagnoses and personalized treatment modalities, highlighting the complex interplay between genetic, environmental, and psychosocial factors. It calls for a deeper understanding of these neuropsychological processes to enhance diagnostic accuracy and therapeutic outcomes.

Evaluating causal psychological models: A study of language theories of autism using a large sample

We used a large convenience sample (n = 22,223) from the Simons Powering Autism Research (SPARK) dataset to evaluate causal, explanatory theories of core autism symptoms. In particular, the data-items collected supported the testing of theories that posited altered language abilities as cause of social withdrawal, as well as alternative theories that competed with these language theories. Our results using this large dataset converge with the evolution of the field in the decades since these theories were first proposed, namely supporting primary social withdrawal (in some cases of autism) as a cause of altered language development, rather than vice versa. To accomplish the above empiric goals, we used a highly theory-constrained approach, one which differs from current data-driven modeling trends but is coherent with a very recent resurgence in theory-driven psychology. In addition to careful explication and formalization of theoretical accounts, we propose three principles for future work of this type: specification, quantification, and integration. Specification refers to constraining models with pre-existing data, from both outside and within autism research, with more elaborate models and more veridical measures, and with longitudinal data collection. Quantification refers to using continuous measures of both psychological causes and effects, as well as weighted graphs. This approach avoids "universality and uniqueness" tests that hold that a single cognitive difference could be responsible for a heterogeneous and complex behavioral phenotype. Integration of multiple explanatory paths within a single model helps the field examine for multiple contributors to a single behavioral feature or to multiple behavioral features. It also allows integration of explanatory theories across multiple current-day diagnoses and as well as typical development.

Identifying transdiagnostic biological subtypes across schizophrenia, bipolar disorder, and major depressive disorder based on lipidomics profiles

Emerging evidence has demonstrated overlapping biological abnormalities underlying schizophrenia (SCZ), bipolar disorder (BP), and major depressive disorder (MDD); these overlapping abnormalities help explain the high heterogeneity and the similarity of patients within and among diagnostic categories. This study aimed to identify transdiagnostic subtypes of these psychiatric disorders based on lipidomics abnormalities. We performed discriminant analysis to identify lipids that classified patients (N = 349, 112 with SCZ, 132 with BP, and 105 with MDD) and healthy controls (N = 198). Ten lipids that mainly regulate energy metabolism, inflammation, oxidative stress, and fatty acylation of proteins were identified. We found two subtypes (named Cluster 1 and Cluster 2 subtypes) across patients with SCZ, BP, and MDD by consensus clustering analysis based on the above 10 lipids. The distribution of clinical diagnosis, functional impairment measured by Global Assessment of Functioning (GAF) scales, and brain white matter abnormalities measured by fractional anisotropy (FA) and radial diffusivity (RD) differed in the two subtypes. Patients within the Cluster 2 subtype were mainly SCZ and BP patients and featured significantly elevated RD along the genu of corpus callosum (GCC) region and lower GAF scores than patients within the Cluster 1 subtype. The SCZ and BP patients within the Cluster 2 subtype shared similar biological patterns; that is, these patients had comparable brain white matter abnormalities and functional impairment, which is consistent with previous studies. Our findings indicate that peripheral lipid abnormalities might help identify homogeneous transdiagnostic subtypes across psychiatric disorders.

Associations of cognitive impairment in patients with schizophrenia with genetic features and with schizophrenia-related structural and functional brain changes

Cognitive impairment is highly prevalent in patients with major psychiatric disorders (MPDs), including schizophrenia (SCZ), bipolar disorder, major depressive disorder, in whom it can be highly disruptive to community functioning and worsen prognosis. Previously, genetic factors and cognitive impairments in MPD patients have been examined mostly in isolated circuits rather than in the whole brain. In the present study, genetic, neuroimaging, and psychometric approaches were combined to investigate the relationship among genetic factors, alterations throughout the brain, and cognitive impairments in a large cohort of patients diagnosed with SCZ, with a reference healthy control (HC) group. Single nucleotide polymorphisms (SNPs) in SCZ-risk genes were found to be strongly related to cognitive impairments as well as to gray matter volume (GMV) and functional connectivity (FC) alterations in the SCZ group. Annotating 136 high-ranking SNPs revealed 65 affected genes (including PPP1R16B, GBBR2, PDE4B, CANCNA1C, SLC12AB, SATB2, MAG12, and SATB2). Only one, a PDE4B SNP (rs1006737), correlated with GMV (r = 0:19 p = 0.015) and FC (r = 0.21, p = 0.0074) in SCZ patients. GMV and FC alterations correlated with one another broadly across brain regions. Moreover, the present data demonstrate three-way SNP-FC-GMV associations in patients with SCZ, thus providing clues regarding potential genetic bases of cognition impairments in SCZ. SNP-FC-GMV relationships correlated with visual learning and reasoning dimensions of cognition. These data provide evidence that SCZ-related cognitive impairments may reflect genetically underlain whole-brain structural and functional alterations.

Transcranial direct current stimulation of the occipital lobes with adjunct lithium attenuates the progression of cognitive impairment in patients with first episode schizophrenia

BACKGROUND

There is no standard effective treatment for schizophrenia-associated cognitive impairment. Efforts to use non-invasive brain stimulation for this purpose have been focused mostly on the frontal cortex, with little attention being given to the occipital lobe.

MATERIALS AND METHODS

We compared the effects of nine intervention strategies on cognitive performance in psychometric measures and brain connectivity measured obtained from functional magnetic resonance imaging analyses. The strategies consisted of transcranial direct current stimulation (t-DCS) or repetitive transcranial magnetic stimulation (r-TMS) of the frontal lobe or of the occipital alone or with adjunct lithium, or lithium monotherapy. We measured global functional connectivity density (gFCD) voxel-wise.

RESULTS

Although all nine patient groups showed significant improvements in global disability scores (GDSs) following the intervention period (vs. before), the greatest improvement in GDS was observed for the group that received occipital lobe-targeted t-DCS with adjunct lithium therapy. tDCS of the occipital lobe improved gFCD throughout the brain, including in the frontal lobes, whereas stimulation of the frontal lobes had less far-reaching benefits on gFCD in the brain. Adverse secondary effects (ASEs) such as heading, dizziness, and nausea, were commonly experienced by patients treated with t-DCS and r-TMS, with or without lithium, whereas ASEs were rare with lithium alone.

CONCLUSION

The most effective treatment strategy for impacting cognitive impairment and brain communication was t-DCS stimulation of the occipital lobe with adjunct lithium therapy, though patients often experienced headache with dizziness and nausea after treatment sessions.

Violence, neurocognitive function and clinical correlates in patients with schizophrenia

BACKGROUND

Schizophrenia patients with violent behavior are a severe public health concern, but the correlates of this violent behavior are unknown. Additionally, the relationship between neurocognitive function and violent behavior in Chinese patients with schizophrenia has not yet been investigated.

METHODS

A total of 337 schizophrenia inpatients were recruited. The Positive and Negative Syndrome Scale (PANSS) was used to assess psychopathological symptoms. Neurocognitive functioning was evaluated using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS).

RESULTS

The percentage of violent behavior was 10.4% in patients with schizophrenia. Patients with violent behavior had higher PANSS-positive, excited, and total subscale scores than patients who did not show violent behavior. Patients with violent behavior also had lower RBANS language, semantic fluency, and total subscale scores. Gender (OR = 0.066∼0.819, p = 0.023), illness duration (OR = 0.876∼0.971, p = 0.002), smoking (OR = 1.127∼2.950, p = 0.014), the PANSS positive subscale (OR = 1.050∼1.197, p = 0.001), and the RBANS language subscale (OR = 0.927∼0.987, p = 0.005) significantly contributed to the development of violent behavior in schizophrenia patients.

CONCLUSION

Our findings revealed that cognitive and clinical assessments should be considered in comprehensive assessments of future risks of violence in schizophrenia patients.

Reduced white matter microstructure in bipolar disorder with and without psychosis

OBJECTIVES

Affective and psychotic features overlap considerably in bipolar I disorder, complicating efforts to determine its etiology and develop targeted treatments. In order to clarify whether mechanisms are similar or divergent for bipolar disorder with psychosis (BDP) and bipolar disorder with no psychosis (BDNP), neurobiological profiles for both the groups must first be established. This study examines white matter structure in the BDP and BDNP groups, in an effort to identify portions of white matter that may differ between the bipolar and healthy groups or between the bipolar subgroups themselves.

METHODS

Diffusion-weighted imaging data were acquired from participants with BDP (n = 45), BDNP (n = 40), and healthy comparisons (HC) (n = 66). Fractional anisotropy (FA), radial diffusivity (RD), and spin distribution function (SDF) values indexing white matter diffusivity or spin density were calculated and compared between the groups.

RESULTS

In comparisons between both the bipolar groups and HC, FA (FDR < 0.00001) and RD (FDR = 0.0037) differed minimally, in localized portions of the left cingulum and corpus callosum, while reductions in SDF (FDR = 0.0002) were more widespread. The bipolar subgroups did not differ from each other on FA, RD, or SDF metrics.

CONCLUSIONS

Together, these results demonstrate a novel profile of white matter differences in bipolar disorder and suggest that this white matter pathology is associated with the affective disturbance common to those with bipolar disorder rather than the psychotic features unique to some. The white matter alterations identified in this study may provide substrates for future studies examining specific mechanisms that target affective domains of illness.

Genome-wide association study accounting for anticholinergic burden to examine cognitive dysfunction in psychotic disorders

Identifying genetic contributors to cognitive impairments in psychosis-spectrum disorders can advance understanding of disease pathophysiology. Although CNS medications are known to affect cognitive performance, they are often not accounted for in genetic association studies. In this study, we performed a genome-wide association study (GWAS) of global cognitive performance, measured as composite z-scores from the Brief Assessment of Cognition in Schizophrenia (BACS), in persons with psychotic disorders and controls (N = 817; 682 cases and 135 controls) from the Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) study. Analyses accounting for anticholinergic exposures from both psychiatric and non-psychiatric medications revealed five significantly associated variants located at the chromosome 3p21.1 locus, with the top SNP rs1076425 in the inter-alpha-trypsin inhibitor heavy chain 1 (ITIH1) gene (P = 3.25×E-9). The inclusion of anticholinergic burden improved association models (P < 0.001) and the number of significant SNPs identified. The effect sizes and direction of effect of the top variants remained consistent when investigating findings within individuals receiving specific antipsychotic drugs and after accounting for antipsychotic dose. These associations were replicated in a separate study sample of untreated first-episode psychosis. The chromosome 3p21.1 locus was previously reported to have association with the risk for psychotic disorders and cognitive performance in healthy individuals. Our findings suggest that this region may be a psychosis risk locus that is associated with cognitive mechanisms. Our data highlight the general point that the inclusion of medication exposure information may improve the detection of gene-cognition associations in psychiatric genetic research.

Transdiagnostic comparison of visual working memory capacity in bipolar disorder and schizophrenia

BACKGROUND

Impaired working memory is a core cognitive deficit in both bipolar disorder and schizophrenia. Its study might yield crucial insights into the underpinnings of both disorders on the cognitive and neurophysiological level. Visual working memory capacity is a particularly promising construct for such translational studies. However, it has not yet been investigated across the full spectrum of both disorders. The aim of our study was to compare the degree of reductions of visual working memory capacity in patients with bipolar disorder (PBD) and patients with schizophrenia (PSZ) using a paradigm well established in cognitive neuroscience.

METHODS

62 PBD, 64 PSZ, and 70 healthy controls (HC) completed a canonical visual change detection task. Participants had to encode the color of four circles and indicate after a short delay whether the color of one of the circles had changed or not. We estimated working memory capacity using Pashler's K.

RESULTS

Working memory capacity was significantly reduced in both PBD and PSZ compared to HC. We observed a small effect size (r = .202) for the difference between HC and PBD and a medium effect size (r = .370) for the difference between HC and PSZ. Working memory capacity in PSZ was also significantly reduced compared to PBD with a small effect size (r = .201). Thus, PBD showed an intermediate level of impairment.

CONCLUSIONS

These findings provide evidence for a gradient of reduced working memory capacity in bipolar disorder and schizophrenia, with PSZ showing the strongest degree of impairment. This underscores the importance of disturbed information processing for both bipolar disorder and schizophrenia. Our results are compatible with the cognitive manifestation of a neurodevelopmental gradient affecting bipolar disorder to a lesser degree than schizophrenia. They also highlight the relevance of visual working memory capacity for the development of both behavior- and brain-based transdiagnostic biomarkers.

Generalized neurocognitive impairment in individuals at ultra-high risk for psychosis: The possible key role of slowed processing speed

OBJECTIVE

Widespread neurocognitive impairment is well-established in individuals at ultra-high risk (UHR) for developing psychoses, but it is unknown whether slowed processing speed may underlie impairment in other neurocognitive domains, as found in schizophrenia. The study delineated domain functioning in a UHR sample and examined if neurocognitive slowing might account for deficits across domains.

METHODS

The cross-sectional study included 50 UHR individuals with no (n = 38) or minimal antipsychotic exposure (n = 12; mean lifetime dose of haloperidol equivalent = 17.56 mg; SD = 13.04) and 50 matched healthy controls. Primary analyses compared group performance across neurocognitive domains before and after covarying for processing speed. To examine the specificity of processing speed effects, post hoc analyses examined the impact of the other neurocognitive domains and intelligence as covariates.

RESULTS

UHR individuals exhibited significant impairment across all neurocognitive domains (all ps ≤ .010), with medium to large effect sizes (Cohen's ds = -0.53 to -1.12). Only processing speed used as covariate eliminated significant between-group differences in all other domains, reducing unadjusted Cohen's d values with 68% on average, whereas the other domains used as covariates averagely reduced unadjusted Cohen's d values with 20% to 48%. When covarying each of the other domains after their shared variance with speed of processing was removed, all significant between-group domain differences remained (all ps ≤ .024).

CONCLUSION

Slowed processing speed may underlie generalized neurocognitive impairment in UHR individuals and represent a potential intervention target.

Distinguishing patterns of impairment on inhibitory control and general cognitive ability among bipolar with and without psychosis, schizophrenia, and schizoaffective disorder

BACKGROUND

Deficits in inhibitory control on a Stop Signal Task (SST) were previously observed to be of similar magnitude across schizophrenia, schizoaffective, and bipolar disorder with psychosis, despite variation in general cognitive ability. Understanding different patterns of performance on the SST may elucidate different pathways to the impaired inhibitory control each group displayed. Comparing nonpsychotic bipolar disorder to the psychosis groups on SST may also expand our understanding of the shared neurobiology of this illness spectrum.

METHODS

We tested schizophrenia (n = 220), schizoaffective (n = 216), bipolar disorder with (n = 192) and without psychosis (n = 67), and 280 healthy comparison participants with a SST and the Brief Assessment of Cognition in Schizophrenia (BACS), a measure of general cognitive ability.

RESULTS

All patient groups had a similar degree of impaired inhibitory control over prepotent responses. However, bipolar groups differed from schizophrenia and schizoaffective groups in showing speeded responses and inhibition errors that were not accounted for by general cognitive ability. Schizophrenia and schizoaffective groups had a broader set of deficits on inhibition and greater general cognitive deficit, which fully accounted for the inhibition deficits. No differences were found between the clinically well-matched bipolar with and without psychosis groups, including for inhibitory control or general cognitive ability.

CONCLUSIONS

We conclude that 1) while impaired inhibitory control on a SST is of similar magnitude across the schizo-bipolar spectrum, including nonpsychotic bipolar, different mechanisms may underlie the impairments, and 2) history of psychosis in bipolar disorder does not differentially impact inhibitory behavioral control or general cognitive abilities.

Catechol-O-methyltransferase genotype differentially contributes to the flexibility and stability of cognitive sets in patients with psychotic disorders and their first-degree relatives

Dopaminergic activity in prefrontal cortex is modulated by the low (Met) and high (Val) activity of the rs4680 Val158Met single nucleotide polymorphism (SNP) in the Catechol-O-Methyltransferase (COMT) gene. While this has been related to working memory maintenance in patients with schizophrenia, the familial pattern, impact across the psychosis spectrum, and the role of this genotype on other aspects of behavior, such as cognitive flexibility, remains unclear. The relationship between COMT Val158Met genotype and both cognitive stability and flexibility were assessed using the Penn Conditional Exclusion Test (PCET) in healthy controls (n = 241), patients with psychotic disorders (n = 542), and their first-degree relatives (n = 613) from the Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) consortium. Higher rates of perseverative errors (poor flexibility) were associated with the low-activity COMT genotype (Met allele carriers) in probands compared to their first-degree relatives with the same genotype. Probands and first-degree relatives homozygous for the high-activity COMT enzyme (Val/Val) showed elevated rates of regressive errors (poor stability) compared to controls. Conversely, heterozygous relatives had comparable regressive error rates to controls, with probands showing elevated errors in comparison. These findings suggest that impaired suppression of learned response patterns and reduced stability of mental sets may be a familial intermediate cognitive phenotype related to Val COMT allele genotype.

Association of schizophrenia polygenic risk score with data-driven cognitive subtypes: A six-year longitudinal study in patients, siblings and controls

Cross-sectional studies have shown that the polygenic risk score for schizophrenia (PRS_SCZ) may influence heterogeneity in cognitive performance although evidence from family-based longitudinal study is limited. This study aimed to identify trajectories of cognitive function and assess whether the PRS_SCZ is associated with baseline cognitive performance and predicted six-year trajectories. We included 1119 patients with a schizophrenia spectrum disorder, and 1059 unaffected siblings and 586 unrelated controls who are eligible at baseline. Genotype data were collected at baseline, whereas clinical and sociodemographic data were collected at baseline, three and six years. Group-based trajectory modeling was applied on a weighted standardized composite score of general cognition to unravel cognitive subtypes and explore trajectories over time. We followed a standard procedure to calculate the polygenic risk score. A random-effects ordinal regression model was used to investigate the association between PRS_SCZ and cognitive subtypes. Five cognitive subtypes with variable trajectories were found in patients, four in siblings and controls, and six in all combined samples. PRS_SCZ significantly predicted poor cognitive trajectories in patients, siblings and all samples. After Bonferroni correction and adjustment for non-genetic factors, only the results in all combined sample remained significant. Cognitive impairment in schizophrenia is heterogeneous and may be linked with high PRS_SCZ. Our finding confirmed at least in all combined samples the presence of genetic overlap between schizophrenia and cognitive function and can give insight into the mechanisms of cognitive deficits.

[Procognitive effects of transcranial magnetic stimulation in the light of neurocognitive deficit in schizophrenia]

Transcranial magnetic stimulation (TMS) is a relatively new method of non-invasive therapy of mental and neurological diseases that has great potential of therapeutic and diagnostic application. In schizophrenia, TMS may exert a positive effect on cognitive deficit. However this issue remains open. The authors analyze recent studies focused on the dynamics of neurocognitive deficit in TMS therapy and consider clinical effects of TMS in schizophrenia. The analysis has shown that TMS is successfully implemented in treatment of auditory positive symptoms and studies on its effect on negative symptoms of schizophrenia are perspective. Procognitive effect was found in working memory domain, and partially in perception domain within the perception of faces and facial expressions. The data on regulative functions, attention, speech, and nondeclarative memory remains controversial. It has been concluded that further research is needed to clarify the place of TMS in schizophrenia therapy.

Neurocognition as a predictor of transition to psychotic disorder and functional outcomes in ultra-high risk participants: Findings from the NEURAPRO randomized clinical trial

BACKGROUND

Neurocognitive impairments experienced by individuals at ultra-high risk (UHR) for psychosis are potential predictors of outcome within this population, however there is inconsistency regarding the specific neurocognitive domains implicated. This study aimed to examine whether baseline neurocognition predicted transition to psychosis, or functional outcomes, at medium-term (mean = 3.4 years) follow-up, while controlling for other clinical/treatment variables associated with transition to psychosis.

METHOD

Analysis of data collected as part of a multi-centre RCT of omega-3 fatty acids and cognitive-behavioural case management (NEURAPRO) for UHR individuals was conducted on the 294 participants (134 males, 160 females) who completed neurocognitive assessment (Brief Assessment of Cognition for Schizophrenia) at baseline. Transition to psychosis was determined using the Comprehensive Assessment of At-Risk Mental States (CAARMS), and functioning was measured with the Global Functioning: Social and Role Scales.

RESULTS

Mean baseline z-scores indicated that UHR participants performed a quarter to half a standard deviation below normative means in all domains (range mean z = -0.24 to -0.47), except for executive functioning (mean z = 0.16). After adjusting for covariates, poorer Executive (p = .010) and Motor (p = .030) functions were predictive of transition to psychosis. Processing Speed and Verbal Fluency were significant predictors of role functioning at 12 months (p = .004), and social functioning at medium-term follow-up (p = .015), respectively.

CONCLUSIONS

Neurocognitive abilities are independent predictors of both transition to psychosis and functional outcomes within the UHR population. Further research is needed to determine the best combination of risk variables in UHR individuals for prediction of psychosis transition, functioning and other psychopathology outcomes.

Beneficial and adverse effects of antipsychotic medication on cognitive flexibility are related to COMT genotype in first episode psychosis

This study evaluated the ability to flexibly shift cognitive set and to consistently maintain a new response preference using the Penn Conditional Exclusion Test (PCET). The relationship of performance errors with catechol-O-methyltransferase (COMT) rs4680 (Val158Met) genotype (Met carriers vs. Val homozygotes) on test performance before and after antipsychotic treatment in 32 first episode psychosis (FEP) patients was examined. After treatment, patients demonstrated a mixture of beneficial and adverse cognitive outcomes that varied in relation to COMT genotype. Met carriers showed decreased perseverative and regressive errors, reflecting improved cognitive flexibility and enhanced stability of behavioral preferences, respectively. In contrast, Val homozygotes exhibited an increase in regressive errors after treatment. These findings suggest that Val homozygotes may be vulnerable to adverse effects of antipsychotic medication on cognitive processes that maintain consistent adaptive response preferences, an ability linked to the striatum in rodent models.

Multivariate Relationships Between Cognition and Brain Anatomy Across the Psychosis Spectrum

BACKGROUND

Cognitive and structural brain abnormalities range from mild to severe in psychosis. The relationships of specific cognitive functions to specific brain structures across the psychosis spectrum is less certain.

METHODS

Participants (n = 678) with bipolar, schizoaffective, or schizophrenia psychoses and healthy control subjects were recruited via the Bipolar-Schizophrenia Network for Intermediate Phenotypes. The Schizo-Bipolar Scale was used to create a psychosis continuum (from purely affective to purely nonaffective). Canonical correlation between 14 cognitive measures and structural brain measures (gray matter volume, cortical thickness, cortical surface area, and local gyrification indices) for 68 neocortical regions yielded constructs that defined shared cognition-brain structure relationships. Canonical discriminant analysis was used to integrate these constructs and efficiently summarize cognition-brain structure relationships across the psychosis continuum.

RESULTS

General cognition was associated with larger gray matter volumes and thicker cortices but smaller cortical surface area in frontoparietal regions. Working memory was associated with larger volume and surface area in frontotemporal regions. Faster response speed was associated with thicker frontal cortices. Constructs that captured general cognitive ability and working memory and their relationship to cortical volumes primarily defined an ordered psychosis spectrum (purely affective, least abnormal through purely nonaffective, and most abnormal). A construct that captured general cognitive ability and its relationship to cortical surface area differentiated purely affective cases from other groups.

CONCLUSIONS

General cognition and working memory with cortical volume deviations characterized more nonaffective psychoses. Alternatively, affective psychosis cases with general cognitive deficits had deviations in cortical surface area, perhaps accounting for heterogeneous findings across previous studies.

Association between catechol-O-methyltransferase genetic variation and functional connectivity in patients with first-episode schizophrenia

Dopamine in the prefrontal cortex (PFC) plays an important role in cognitive performance and regulates by catechol-O-methyltransferase (COMT) expression. To clarify the effect of COMT genotype on cognitive function in patients with schizophrenia, we performed DNA genotyping, cognitive evaluations, and functional magnetic resonance imaging (fMRI) in antipsychotic-naïve patients with first-episode schizophrenia (FES) and matched healthy control subjects. We found that all cognitive domains were impaired in patients with FES compared with healthy subjects. Moreover, COMT genotype influenced the verbal learning performance in healthy subjects, but not in patients with FES. Resting-state fMRI data revealed that patients with FES exhibited higher functional connectivity degree centrality in the medial PFC and lower degree centrality in the parietal-occipital junction than healthy subjects. Furthermore, patients with FES who were COMT Met allele carriers had higher degree centrality in the medial PFC than those with the Val/Val genotype. In contrast, in healthy controls, Met allele carriers exhibited higher degree centrality than healthy controls with the Val/Val genotype in the left hippocampus and left amygdala. There was a negative correlation between the degree centrality value in medial PFC and score of the Hopkins Verbal Learning Test-Revised (HVLT-R) in FES patients with the Met allele. Our findings suggest that COMT genotype differentially influences pathways related to cognitive performance in patients with FES versus healthy individuals, providing an important insight into schizophrenia pathophysiology.

Deficits in visual working-memory capacity and general cognition in African Americans with psychosis

On average, patients with psychosis perform worse than controls on visual change-detection tasks, implying that psychosis is associated with reduced capacity of visual working memory (WM). In the present study, 79 patients diagnosed with various psychotic disorders and 166 controls, all African Americans, completed a change-detection task and several other neurocognitive measures. The aims of the study were to (1) determine whether we could observe a between-group difference in performance on the change-detection task in this sample; (2) establish whether such a difference could be specifically attributed to reduced WM capacity (k); and (3) estimate k in the context of the general cognitive deficit in psychosis. Consistent with previous studies, patients performed worse than controls on the change-detection task, on average. Bayesian hierarchical cognitive modeling of the data suggested that this between-group difference was driven by reduced k in patients, rather than differences in other psychologically meaningful model parameters (guessing behavior and lapse rate). Using the same modeling framework, we estimated the effect of psychosis on k while controlling for general intellectual ability (g, obtained from the other neurocognitive measures). The results suggested that reduced k in patients was stronger than predicted by the between-group difference in g. Moreover, a mediation analysis suggested that the relationship between psychosis and g (i.e., the general cognitive deficit) was mediated by k. The results were consistent with the idea that reduced k is a specific deficit in psychosis, which contributes to the general cognitive deficit.

Deviation from expected cognitive ability across psychotic disorders

Patients with schizophrenia show a deficit in cognitive ability compared to estimated premorbid and familial intellectual abilities. However, the degree to which this pattern holds across psychotic disorders and is familial is unclear. The present study examined deviation from expected cognitive level in schizophrenia, schizoaffective disorder, and psychotic bipolar disorder probands and their first-degree relatives. Using a norm-based regression approach, parental education and WRAT-IV Reading scores (both significant predictors of cognitive level in the healthy control group) were used to predict global neuropsychological function as measured by the composite score from the Brief Assessment of Cognition in Schizophrenia (BACS) test in probands and relatives. When compared to healthy control group, psychotic probands showed a significant gap between observed and predicted BACS composite scores and a greater likelihood of robust cognitive decline. This effect was not seen in unaffected relatives. While BACS and WRAT-IV Reading scores were themselves highly familial, the decline in cognitive function from expectation had lower estimates of familiality. Thus, illness-related factors such as epigenetic, treatment, or pathophysiological factors may be important causes of illness related decline in cognitive abilities across psychotic disorders. This is consistent with the markedly greater level of cognitive impairment seen in affected individuals compared to their unaffected family members.

Do cognitive deficits predict negative emotionality and aggression in schizophrenia?

Schizophrenia is associated with an elevated risk of aggression. Cognitive deficits have been associated with inpatient aggression and future violence. The relationship between cognitive deficits and violent behavior has however been inconsistent across studies. In addition, studies have failed to inform how cognitive deficits may contribute to aggression in schizophrenia. The current study examined the association of cognitive deficits with schizophrenia-related aggression and violent offending. It also explored the putative mediating role of negative emotionality on the impact of cognitive deficits on aggression. People with schizophrenia and schizoaffective disorder (N = 78) were recruited from a state hospital. Participants were classified based on their history of violent offending. Participants completed measures of cognition, symptoms, and aggression. Deficits in working memory, reasoning/problem-solving, and verbal learning were the most prioritized for the prediction of violent offender status. Violent offenders demonstrated greater impairments in most cognitive domains especially working memory and verbal learning. Offenders also demonstrated greater negative emotionality, excitement/agitation, and incidents of verbal and physical aggression. Negative emotionality and excitement/agitation fully transmitted the effect of cognitive deficits on impulsive aggression in meditational models. Cognitive deficits increase the risk of impulsive aggression in schizophrenia via inefficient regulation of negative affective states.

Assessing the Relationship between Performance on the University of California Performance Skills Assessment (UPSA) and Outcomes in Schizophrenia: A Systematic Review and Evidence Synthesis

OBJECTIVE

To perform a systematic review of the published literature to evaluate how functional capacity, as measured by the University of California at San Diego (UCSD) Performance-based Skills Assessment (UPSA), relates to other functional measures and real-world outcomes among individuals with schizophrenia.

METHODS

The MEDLINE® and Embase® databases were searched to identify joint evaluations with UPSA and key functional outcomes (functional scale measures; generic or disease-specific, health-related quality of life [HRQoL]; or real-world outcomes [residential status; employment status]) in patients with schizophrenia. Pearson correlations were estimated between UPSA scores, HRQoL, other functional scale measures, and real-world outcomes, for outcomes described in at least six studies.

RESULTS

The synthesis included 76 studies that provided 73 unique data sets. Quantitative assessment between the Specific Level of Function (SLOF) (n=18) scores and UPSA scores demonstrated a moderate borderline-significant correlation (0.45, p=0.06). Quantitative analysis of the relationship between the Global Assessment of Functioning (GAF) (n=11) and the Multidimensional Scale of Independent Functioning (MSIF) (n=6) scales revealed moderate and small nonsignificant Pearson correlations of -0.34 (p=0.31) and 0.12 (p=0.83), respectively. There was a small borderline-significant correlation between UPSA score and residential status (n=36; 0.31; p=0.08), while no correlation was found between UPSA score and employment status (n=19; 0.04; p=0.88).

CONCLUSION

The SLOF was the most often used functional measure and had the strongest observed correlation with the UPSA. Although knowledge gaps remain, evidence from this review indicates that there is a quantitative relationship between functional capacity and real-world outcomes in individuals with schizophrenia.

Explicit and implicit reinforcement learning across the psychosis spectrum

Motivational and hedonic impairments are core features of a variety of types of psychopathology. An important aspect of motivational function is reinforcement learning (RL), including implicit (i.e., outside of conscious awareness) and explicit (i.e., including explicit representations about potential reward associations) learning, as well as both positive reinforcement (learning about actions that lead to reward) and punishment (learning to avoid actions that lead to loss). Here we present data from paradigms designed to assess both positive and negative components of both implicit and explicit RL, examine performance on each of these tasks among individuals with schizophrenia, schizoaffective disorder, and bipolar disorder with psychosis, and examine their relative relationships to specific symptom domains transdiagnostically. None of the diagnostic groups differed significantly from controls on the implicit RL tasks in either bias toward a rewarded response or bias away from a punished response. However, on the explicit RL task, both the individuals with schizophrenia and schizoaffective disorder performed significantly worse than controls, but the individuals with bipolar did not. Worse performance on the explicit RL task, but not the implicit RL task, was related to worse motivation and pleasure symptoms across all diagnostic categories. Performance on explicit RL, but not implicit RL, was related to working memory, which accounted for some of the diagnostic group differences. However, working memory did not account for the relationship of explicit RL to motivation and pleasure symptoms. These findings suggest transdiagnostic relationships across the spectrum of psychotic disorders between motivation and pleasure impairments and explicit RL. (PsycINFO Database Record

Cognitive impairment in first-episode drug-naïve patients with schizophrenia: Relationships with serum concentrations of brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor

OBJECTIVES

Evidence suggests that brain-derived neurotrophic factor (BDNF) and glial cell line -derived neurotrophic factor (GDNF) are important in the regulation of synaptic plasticity, which plays a key role in the cognitive processes in psychiatric disorders. Our work aimed at exploring the associations between serum BDNF and GDNF levels and cognitive functions in first-episode drug-naïve (FEDN) patients with schizophrenia.

METHODS

The BDNF and GDNF levels of 58 FEDN patients and 55 age- and sex-matched healthy controls were measured and test subjects were examined using several neurocognitive tests including the verbal fluency test (VFT), the trail making test (TMT), the digit span test (DST), and the Stroop test.

RESULTS

Patients performed significantly worse than controls in nearly all neurocognitive performances except the forward subscale part of the DST. BDNF levels were inversely correlated to TMT-part B scores and positively correlated to VFT-action in the FEDN group. GDNF levels showed a positive correlation with VFT-action scores and a negative correlation with TMT-part B scores of these patients.

CONCLUSION

Current data suggests that cognitive dysfunction widely exists in the early stages of schizophrenia. BDNF and GDNF may be jointly contributed to the pathological mechanisms involved in cognitive impairment in FEDN patients with schizophrenia.

Transdiagnostic Associations Between Functional Brain Network Integrity and Cognition

IMPORTANCE

Cognitive impairment occurs across the psychosis spectrum and is associated with functional outcome. However, it is unknown whether these shared manifestations of cognitive dysfunction across diagnostic categories also reflect shared neurobiological mechanisms or whether the source of impairment differs.

OBJECTIVE

To examine whether the general cognitive deficit observed across psychotic disorders is similarly associated with functional integrity of 2 brain networks widely implicated in supporting many cognitive domains.

DESIGN, SETTING, AND PARTICIPANTS

A total of 201 healthy control participants and 375 patients with psychotic disorders from the Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) consortium were studied from September 29, 2007, to May 31, 2011. The B-SNIP recruited healthy controls and stable outpatients from 6 sites: Baltimore, Maryland; Boston, Massachusetts; Chicago, Illinois; Dallas, Texas; Detroit, Michigan; and Hartford, Connecticut. All participants underwent cognitive testing and resting-state functional magnetic resonance imaging. Data analysis was performed from April 28, 2015, to February 21, 2017.

MAIN OUTCOMES AND MEASURES

The Brief Assessment of Cognition in Schizophrenia was used to measure cognitive ability. A principal axis factor analysis on the Brief Assessment of Cognition in Schizophrenia battery yielded a single factor (54% variance explained) that served as the measure of general cognitive ability. Functional network integrity measures included global and local efficiency of the whole brain, cingulo-opercular network (CON), frontoparietal network, and auditory network and exploratory analyses of all networks from the Power atlas. Group differences in network measures, associations between cognition and network measures, and mediation models were tested.

RESULTS

The final sample for the current study included 201 healthy controls, 143 patients with schizophrenia, 103 patients with schizoaffective disorder, and 129 patients with psychotic bipolar disorder (mean [SD] age, 35.1 [12.0] years; 281 male [48.8%] and 295 female [51.2%]; 181 white [31.4%], 348 black [60.4%], and 47 other [8.2%]). Patients with schizophrenia (Cohen d = 0.36, P < .001) and psychotic bipolar disorder (Cohen d = 0.33, P = .002) had significantly reduced CON global efficiency compared with healthy controls. All patients with psychotic disorders had significantly reduced CON local efficiency, but the clinical groups did not differ from one another. The CON global efficiency was significantly associated with general cognitive ability across all groups (β = 0.099, P = .009) and significantly mediated the association between psychotic disorder status and general cognition (β = -0.037; 95% CI, -0.076 to -0.014). Subcortical network global efficiency was also significantly reduced in psychotic disorders (F3,587 = 4.01, P = .008) and positively predicted cognitive ability (β = 0.094, P = .009).

CONCLUSIONS AND RELEVANCE

These findings provide evidence that reduced CON and subcortical network efficiency play a role in the general cognitive deficit observed across the psychosis spectrum. They provide new support for the dimensional hypothesis that a shared neurobiological mechanism underlies cognitive impairment in psychotic disorders.

Cognitive effects of adjunctive N-acetyl cysteine in psychosis

BACKGROUND

Cognitive deficits are predictors of functional outcome in patients with psychosis. While conventional antipsychotics are relatively effective on positive symptoms, their impact on negative and cognitive symptoms is limited. Recent studies have established a link between oxidative stress and neurocognitive deficits in psychosis. N-acetylcysteine (NAC), a glutathione precursor with glutamatergic properties, has shown efficacy on negative symptoms and functioning in patients with schizophrenia and bipolar disorder, respectively. However, there are few evidence-based approaches for managing cognitive impairment in psychosis. The present study aims to examine the cognitive effects of adjunctive NAC treatment in a pooled subgroup of participants with psychosis who completed neuropsychological assessment in two trials of both schizophrenia and bipolar disorder.

METHOD

A sample of 58 participants were randomized in a double fashion to receive 2 g/day of NAC (n = 27) or placebo (n = 31) for 24 weeks. Attention, working memory and executive function domains were assessed. Differences between cognitive performance at baseline and end point were examined using Wilcoxon's test. The Mann-Whitney test was used to examine the differences between the NAC and placebo groups at the end point.

RESULTS

Participants treated with NAC had significantly higher working memory performance at week 24 compared with placebo (U = 98.5, p = 0.027).

CONCLUSIONS

NAC may have an impact on cognitive performance in psychosis, as a significant improvement in working memory was observed in the NAC-treated group compared with placebo; however, these preliminary data require replication. Glutamatergic compounds such as NAC may constitute a step towards the development of useful therapies for cognitive impairment in psychosis.

Neurocognitive performance, psychopathology and social functioning in individuals at high risk for schizophrenia or psychotic bipolar disorder

INTRODUCTION

Although cognitive deficits are consistent endophenotypes of schizophrenia and bipolar disorder, findings in psychotic bipolar disorder (BDP) are inconsistent. In this study we compared adult unaffected first-degree relatives of schizophrenia and BDP patients on cognition, psychopathology, social functioning and quality of life.

METHODS

Sixty-six unaffected first-degree relatives of schizophrenia patients (SUnR), 36 unaffected first-degree relatives of BDP patients (BDPUnR) and 102 controls participated in the study. Between-group differences were examined and Discriminant Function Analysis (DFA) predicted group membership.

RESULTS

Visual memory, control inhibition, working memory, cognitive flexibility and abstract reasoning were linearly impaired in the relatives' groups. Poorer verbal fluency and processing speed were evident only in the SUnR group. The SUnR group had higher depressive and somatization symptoms while the BDPUnR group had higher anxiety and lower social functioning compared with the controls. Individuals with superior cognition were more likely to be classified as controls; those with higher social functioning, prolonged processing speed and lower anxiety were more likely to be classified as SUnR.

LIMITATIONS

The relatives' sample is quite heterogeneous; the effects of genetic or environmental risk-factors were not examined.

CONCLUSIONS

Cognitive functions mediated by a fronto-parietal network, show linear impairments in unaffected relatives of BDP and schizophrenia patients; processing speed and verbal fluency impairments were evident only in schizophrenia relatives. Self-perceived symptomatology and social functioning also differ between schizophrenia and BDP relatives. The continuum seen in patients in several indices was also seen in the cognitive impairments in unaffected relatives of schizophrenia and BDP patients.

Consensus paper of the WFSBP Task Force on Biological Markers: Criteria for biomarkers and endophenotypes of schizophrenia part II: Cognition, neuroimaging and genetics

OBJECTIVES

Schizophrenia is a group of severe psychiatric disorders with high heritability but only low odds ratios of risk genes. Despite progress in the identification of pathophysiological processes, valid biomarkers of the disease are still lacking.

METHODS

This comprehensive review summarises recent efforts to identify genetic underpinnings, clinical and cognitive endophenotypes and symptom dimensions of schizophrenia and presents findings from neuroimaging studies with structural, functional and spectroscopy magnetic resonance imaging and positron emission tomography. The potential of findings to be biomarkers of schizophrenia is discussed.

RESULTS

Recent findings have not resulted in clear biomarkers for schizophrenia. However, we identified several biomarkers that are potential candidates for future research. Among them, copy number variations and links between genetic polymorphisms derived from genome-wide analysis studies, clinical or cognitive phenotypes, multimodal neuroimaging findings including positron emission tomography and magnetic resonance imaging, and the application of multivariate pattern analyses are promising.

CONCLUSIONS

Future studies should address the effects of treatment and stage of the disease more precisely and apply combinations of biomarker candidates. Although biomarkers for schizophrenia await validation, knowledge on candidate genomic and neuroimaging biomarkers is growing rapidly and research on this topic has the potential to identify psychiatric endophenotypes and in the future increase insight on individual treatment response in schizophrenia.

Decomposing mechanisms of abnormal saccade generation in schizophrenia patients: Contributions of volitional initiation, motor preparation, and fixation release

Clinical and theoretical models suggest deficient volitional initiation of action in schizophrenia patients. Recent research provided an experimental model of testing this assumption using saccade tasks. However, inconsistent findings necessitate a specification of conditions on which the deficit may occur. The present study sought to detect mechanisms that may contribute to poor performance. Sixteen schizophrenia patients and 16 healthy control participants performed visually guided and two types of volitional saccade tasks. All tasks varied as to whether the initial fixation stimulus disappeared (fixation stimulus offset) or continued during saccade initiation, and whether a direction cue allowed motor preparation of the specific saccade. Saccade latencies of the two groups were differentially affected by task type, fixation stimulus offset, and cueing, suggesting abnormal volitional saccade generation, fixation release, and motor preparation in schizophrenia. However, substantial performance deficits may only occur if all affected processes are required in a task.

Disconnection Between Amygdala and Medial Prefrontal Cortex in Psychotic Disorders

Distracting emotional information impairs attention more in schizophrenia (SCZ) than in never-psychotic individuals. However, it is unclear whether this impairment and its neural circuitry is indicative generally of psychosis, or specifically of SCZ, and whether it is even more specific to certain SCZ symptoms (eg, deficit syndrome). It is also unclear if this abnormality contributes to impaired behavioral performance and real-world functioning. Functional imaging data were recorded while individuals with SCZ, bipolar disorder with psychosis (BDP) and no history of psychotic disorders (CON) attended to identity of faces while ignoring their emotional expressions. We examined group differences in functional connectivity between amygdala, involved in emotional evaluation, and sub-regions of medial prefrontal cortex (MPFC), involved in emotion regulation and cognitive control. Additionally, we examined correlation of this connectivity with deficit syndrome and real-world functioning. Behaviorally, SCZ showed the worst accuracy when matching the identity of emotional vs neutral faces. Neurally, SCZ showed lower amygdala-MPFC connectivity than BDP and CON. BPD did not differ from CON, neurally or behaviorally. In patients, reduced amygdala-MPFC connectivity during emotional distractors was related to worse emotional vs neutral accuracy, greater deficit syndrome severity, and unemployment. Thus, reduced amygdala-MPFC functional connectivity during emotional distractors reflects a deficit that is specific to SCZ. This reduction in connectivity is associated with worse clinical and real-world functioning. Overall, these findings provide support for the specificity and clinical utility of amygdala-MPFC functional connectivity as a potential neural marker of SCZ.

High functioning individuals with schizophrenia have preserved social perception but not mentalizing abilities

Social perception and mentalizing are fundamental social cognitive abilities that are related to functioning and are impaired in schizophrenia. A novel approach to examine the relationship between social cognition and community functioning is to first functionally categorize individuals with schizophrenia and then evaluate social cognitive performance. We evaluated differences in social perception and mentalizing among controls (CON, n=45), high functioning individuals with schizophrenia (HF-SCZ, n=36), and individuals with low functioning schizophrenia (LF-SCZ, n=24). Analyses revealed that HF-SCZ had preserved social perceptual abilities compared to LF-SCZ. Both schizophrenia groups had impaired mentalizing abilities compared to CON, but did not differ from each other. These results suggest that HF-SCZ and LF-SCZ are characterized by differences in the perceptual aspects of social cognition and encourage future research to evaluate the neural basis underlying this preserved ability.

Unitary construct of generalized cognitive ability underlying BACS performance across psychotic disorders and in their first-degree relatives

Despite robust evidence of neurocognitive dysfunction in psychotic patients, the degree of similarity in cognitive architecture across psychotic disorders and among their respective first-degree relatives is not well delineated. The present study examined the latent factor structure of the Brief Assessment of Cognition in Schizophrenia (BACS) neuropsychological battery. Analyses were conducted on 783 psychosis spectrum probands (schizophrenia, schizoaffective, psychotic bipolar), 887 of their first-degree relatives, and 396 non-psychiatric controls from the Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) consortium. Exploratory factor analysis of BACS subtest scores indicated a single-factor solution that was similar across all groups and provided the best overall data fit in confirmatory analyses. Correlations between the standard BACS composite score and the sum of subscale scores weighted by their loadings on this unitary factor were very high in all groups (r≥.99). Thus, the BACS assesses a similar unitary cognitive construct in probands with different psychotic disorders, in their first-degree relatives, and in healthy controls, and this factor is well measured by the test's standard composite score.

Relationship of Cognition to Clinical Response in First-Episode Schizophrenia Spectrum Disorders

First-episode schizophrenia (FES) spectrum disorders are associated with pronounced cognitive dysfunction across all domains. However, less is known about the course of cognitive functioning, following the first presentation of psychosis, and the relationship of cognition to clinical course during initial treatment. The present longitudinal study examined the magnitude of neurocognitive impairment, using the MATRICS Consensus Cognitive Battery, in patients experiencing their first episode of psychosis at baseline and after 12 weeks of randomized antipsychotic treatment with either aripiprazole or risperidone. At baseline, FES patients evidenced marked impairments in cognitive functioning. Notably, performance on the mazes task of planning and reasoning significantly predicted the likelihood of meeting stringent criteria for positive symptom remission during the first 12 weeks of the trial. Performance on indices of general cognitive function, working memory, and verbal learning improved over time, but these improvements were mediated by improvements in both positive and negative symptoms. We did not detect any differential effects of antipsychotic medication assignment (aripiprazole vs risperidone) on cognitive functioning. Our results suggest that a brief paper-and-pencil measure reflecting planning/reasoning abilities may index responsivity to antipsychotic medication. However, improvements in cognitive functioning over time were related to clinical symptom improvement, reflecting "pseudospecificity."

Cluster analysis differentiates high and low community functioning in schizophrenia: Subgroups differ on working memory but not other neurocognitive domains

BACKGROUND

Schizophrenia is characterized by impairment in multiple aspects of community functioning. Available literature suggests that community functioning may be enhanced through cognitive remediation, however, evidence is limited regarding whether specific neurocognitive domains may be treatment targets. We characterized schizophrenia subjects based on their level of community functioning through cluster analysis in an effort to identify whether specific neurocognitive domains were associated with variation in functioning.

METHODS

Schizophrenia (SCZ, n=60) and control (CON, n=45) subjects completed a functional capacity task, social competence role-play, functional attainment interview, and a neuropsychological battery. Multiple cluster analytic techniques were used on the measures of functioning in the schizophrenia subjects to generate functionally-defined subgroups. MANOVA evaluated between-group differences in neurocognition.

RESULTS

The cluster analysis revealed two distinct groups, consisting of 36 SCZ characterized by high levels of community functioning (HF-SCZ) and 24 SCZ with low levels of community functioning (LF-SCZ). There was a main group effect for neurocognitive performance (p<0.001) with CON outperforming both SCZ groups in all neurocognitive domains. Post-hoc tests revealed that HF-SCZ had higher verbal working memory compared to LF-SCZ (p≤0.05, Cohen's d=0.78) but the two groups did not differ in remaining domains.

CONCLUSION

The cluster analysis classified schizophrenia subjects in HF-SCZ and LF-SCZ using a multidimensional assessment of community functioning. Moreover, HF-SCZ demonstrated rather preserved verbal working memory relative to LF-SCZ. The results suggest that verbal working memory may play a critical role in community functioning, and is a potential cognitive treatment target for schizophrenia subjects.

A randomized study of cognitive remediation for forensic and mental health patients with schizophrenia

Cognitive remediation has proven efficacy for improving neurocognition in people with schizophrenia. The current study evaluated the benefits of cognitive remediation on neurocognition, functioning, psychotic symptoms, and aggression in a sample of forensic and mental health patients. Care recipients with schizophrenia or schizoaffective disorder (N = 78) receiving services in the forensic and mental health units of a state hospital were randomized to participate in cognitive remediation versus computer games control activities. Participants' neurocognition, functional capacity, experiential recovery, psychotic symptoms, and aggression incidents were assessed at baseline and posttreatment. Cognitive remediation was associated with improvements in several neurocognitive domains and circumscribed domains of functional capacity. People assigned to cognitive remediation experiences greater reductions in negative symptoms, agitation/excitement, and verbal and physical aggression. In addition to improving neurocognition in long-term hospitalized forensic and mental health patients, cognitive remediation may enhance efforts at reducing negative symptoms, emotion dysregulation, and aggression incidents. Forensic settings may represent a new frontier for the clinical dissemination of cognitive remediation.

Polygenic risk scores in bipolar disorder subgroups

BACKGROUND

Bipolar disorder (BD) is a genetically and clinically heterogeneous disorder. Current classifications of BD rely on clinical presentations without any validating biomarkers, making homogenous and valid subtypes warranted. This study aims at investigating whether a BD polygenic risk score (PGRS) can validate BD subtypes including diagnostic sub-categories (BD-I versus BD-II), patients with and without psychotic symptoms, polarity of first presenting episode and age at onset based groups. We also wanted to investigate whether illness severity indicators were associated with a higher polygenic risk for BD.

METHODS

Analyze differences in BD PGRS scores between suggested subtypes of BD and between healthy controls (CTR) and BD in a sample of N=669 (255 BD and 414 CTR).

RESULTS

The BD PGRS significantly discriminates between BD and CTR (p<0.001). There were no differences in BD PGRS between groups defined by diagnostic sub-categories, presenting polarity and age at onset. Patients with psychotic BD had nominally significantly higher BD PGRS than patients with non-psychotic BD after controlling for diagnostic sub-category (p=0.019). These findings remained trend level significant after Bonferroni corrections (p=0.079).

LIMITATIONS

The low explained variance of the current PGRS method could lead to type II errors.

CONCLUSIONS

There are nominally significant differences in BD PGRS scores between patients with and without psychotic symptoms, indicating that these two forms of BD might represent distinct subtypes of BD based in its polygenic architecture and a division between BD with and without psychotic symptoms could represent a more valid subclassification of BD than current diagnostic sub-categories. If replicated, this finding could affect future research, diagnostics and clinical practice.

Endophenotypes in Schizophrenia for the Perinatal Period: Criteria for Validation

Endophenotypes are disease-associated phenotypes that are thought to reflect the neurobiological or other mechanisms that underlie the more overt symptoms of a psychiatric illness. Endophenotypes have been critical in understanding the genetics, neurobiology, and treatment of schizophrenia. Because psychiatric illnesses have multiple causes, including both genetic and nongenetic risk factors, an endophenotype linked to one of the mechanisms may be expressed more frequently than the disease itself. However, in schizophrenia research, endophenotypes have almost exclusively been studied in older adolescents or adults who have entered or passed through the age of risk for the disorder. Yet, schizophrenia is a neurodevelopmental disorder where prenatal development starts a cascade of brain changes across the lifespan. Endophenotypes have only minimally been utilized to explore the perinatal development of vulnerability. One major impediment to the development of perinatally-useful endophenotypes has been the established validity criteria. For example, the criterion that the endophenotype be more frequently present in those with disease than those without is difficult to demonstrate when there can be a decades-long period between endophenotype measurement and the age of greatest risk for onset of the disorder. This article proposes changes to the endophenotype validity criteria appropriate to perinatal research and reviews how application of these modified criteria helped identify a perinatally-usable phenotype of risk for schizophrenia, P50 sensory gating, which was then used to propose a novel perinatal primary prevention intervention.

Similar verbal memory impairments in schizophrenia and healthy aging. Implications for understanding of neural mechanisms

Memory is impaired in schizophrenia patients but it is not clear whether this is specific to the illness and whether different types of memory (verbal and nonverbal) or memories in different cognitive domains (executive, object recognition) are similarly affected. To study relationships between memory impairments and schizophrenia we compared memory functions in 77 schizophrenia patients, 58 elderly healthy individuals and 41 young healthy individuals. Tests included verbal associative and logical memory and memory in executive and object recognition domains. We compared relationships of memory functions to each other and to other cognitive functions including psychomotor speed and verbal and spatial working memory. Compared to the young healthy group, schizophrenia patients and elderly healthy individuals showed similar severe impairment in logical memory and in the ability to learn new associations (NAL), and similar but less severe impairment in spatial working memory and executive and object memory. Verbal working memory was significantly more impaired in schizophrenia patients than in the healthy elderly. Verbal episodic memory impairment in schizophrenia may share common mechanisms with similar impairment in healthy aging. Impairment in verbal working memory in contrast may reflect mechanisms specific to schizophrenia. Study of verbal explicit memory impairment tapped by the NAL index may advance understanding of abnormal hippocampus dependent mechanisms common to schizophrenia and aging.

A longitudinal study of cortical changes and their cognitive correlates in patients followed up after first-episode psychosis

BACKGROUND

Loss of cortical volume in frontotemporal regions occurs in patients with first-episode psychosis (FEP) and longitudinal studies have reported progressive brain volume changes at different stages of the disease, even if cognitive deficits remain stable over time. We investigated cortical changes in patients over the 2 years following their FEP and their associations with clinical and cognitive measures.

METHOD

Twenty-seven patients after their FEP (20 with schizophrenia, seven with schizo-affective disorder) and 25 healthy controls matched for age and gender participated in this study. Magnetic resonance imaging (MRI) was performed on a 1.5-T scanner both at baseline and after 2 years. Area and thickness of the cortex were measured using surface-based morphometry (SBM). Patients also underwent neuropsychological testing at these two time points.

RESULTS

Progressive cortical thinning in the superior and inferior frontal and, to a lesser extent, superior temporal cortex was observed in patients. Cortical area remained constant. Cortical thinning was associated with duration of treatment at a trend level and was predicted by baseline measures of IQ and working memory. Cortical thinning occurred in the absence of clinical or cognitive deterioration.

CONCLUSIONS

The clinical implications of these cortical changes remain uncertain, but patients with less cognitive reserve may be more vulnerable to developing cortical abnormalities when exposed to medication or other disease-related biological factors.

Theory of Mind in Bipolar Disorder, with Comparison to the Impairments Observed in Schizophrenia

Our ability to make sense of information on the potential intentions and dispositions of others is of paramount importance for understanding their communicative intent, and for judging what an appropriate reaction might be. Thus, anything that impinges on this ability has the potential to cause significant social impairment, and compromise an individual's level of functioning. Both bipolar disorder and schizophrenia are known to feature theory of mind impairment. We conducted a theoretical review to determine the extent and types of theory of mind impairment in bipolar disorder, and evaluate their relationship to medication and symptoms. We also considered possible mediatory mechanisms, and set out to discover what else could be learnt about the impairment in bipolar disorder by comparison to the profile of impairment in schizophrenia. The literature established that in bipolar disorder (i) some form of theory of mind impairment has been observed in all mood states, including euthymia, (ii) the form of theory of mind assessed and task used to make the assessment influence the impairment observed, and (iii) there might be some relationship to cognitive impairment, although a relationship to standard clinical variables was harder to establish. What also became clear in the literature on bipolar disorder itself was the possible relationship of theory of mind impairment to history of psychotic symptoms. Direct comparative studies, including patients with schizophrenia, were thus examined, and provided several important directions for future research on the bases of impairment in bipolar disorder. Particularly prominent was the issue of whether theory of mind impairment could be considered a candidate endophenotype for the psychoses, although current evidence suggests that this may be premature. The differences in impairment across schizophrenia and bipolar disorder may, however, have genuine differential effects on social functioning and the likely success of remediation.

Cognitive impairments in psychotic disorders: common mechanisms and measurement

Decades of research have provided robust evidence of cognitive impairments in psychotic disorders. Individuals with schizophrenia appear to be impaired on the majority of neuropsychological tasks, leading some researchers to argue for a "generalized deficit", in which the multitude of cognitive impairments are the result of a common neurobiological source. One such common mechanism may be an inability to actively represent goal information in working memory as a means to guide behavior, with the associated neurobiological impairment being a disturbance in the function of the dorsolateral prefrontal cortex. Here, we provide a discussion of the evidence for such impairment in schizophrenia, and how it manifests in domains typically referred to as cognitive control, working memory and episodic memory. We also briefly discuss cognitive impairment in affective psychoses, reporting that the degree of impairment is worse in schizophrenia than in bipolar disorder and psychotic major depression, but the profile of impairment is similar, possibly reflecting common mechanisms at the neural level. Given the recent release of the DSM-5, we end with a brief discussion on assessing cognition in the context of diagnosis and treatment planning in psychotic disorders.

Distinguishing between schizophrenia and other psychotic disorders

The Diagnostic and Statistical Manual of Mental Disorders (DSM) has provided diagnostic reliability across observers while neglecting biological validity. The current theme issue explores the boundaries between schizophrenia and bipolar disorder, using neuro-cognition, systems neuroscience, and genetics as points of departure to begin consideration of a biologically based reclassification of these illnesses.