Brief assessment of cognition in schizophrenia: normative data in an English-speaking ethnic Chinese sample

European Psychiatric Association guidance on assessment of cognitive impairment in schizophrenia

Background

Impairment in a wide range of cognitive abilities has been consistently reported in individuals with schizophrenia. Both neurocognitive and social cognitive deficits are thought to underlie severe functional disabilities associated with schizophrenia. Despite the key role in schizophrenia outcome, cognition is still poorly assessed in both research and clinical settings.

Methods

In this guidance paper, we provide a systematic review of the scientific literature and elaborate several recommendations for the assessment of cognitive functions in schizophrenia both in research settings and in real-world clinical practice.

Results

Expert consensus and systematic reviews provided guidance for the optimal assessment of cognitive functions in schizophrenia. Based on the reviewed evidence, we recommend a comprehensive and systematic assessment of neurocognitive and social cognitive domains in schizophrenia, in all phases of the disorder, as well as in subjects at risk to develop psychosis. This European Psychiatric Association guidance recommends not only the use of observer reports but also self-reports and interview-based cognitive assessment tools. The guidance also provides a systematic review of the state of the art of assessment in the first episode of psychosis patients and in individuals at risk for psychosis.

Conclusion

The comprehensive review of the evidence and the recommendations might contribute to advance the field, allowing a better cognitive assessment, and avoiding overlaps with other psychopathological dimensions. The dissemination of this guidance paper may promote the development of shared guidelines concerning the assessment of cognitive functions in schizophrenia, with the purpose to improve the quality of care and to obtain recovery.

Cognitive Subtyping in Schizophrenia: A Latent Profile Analysis

Cognitive dysfunction is a core feature of schizophrenia. The subtyping of cognitive performance in schizophrenia may aid the refinement of disease heterogeneity. The literature on cognitive subtyping in schizophrenia, however, is limited by variable methodologies and neuropsychological tasks, lack of validation, and paucity of studies examining longitudinal stability of profiles. It is also unclear if cognitive profiles represent a single linear severity continuum or unique cognitive subtypes. Cognitive performance measured with the Brief Assessment of Cognition in Schizophrenia was analyzed in schizophrenia patients (n = 767). Healthy controls (n = 1012) were included as reference group. Latent profile analysis was performed in a schizophrenia discovery cohort (n = 659) and replicated in an independent cohort (n = 108). Longitudinal stability of cognitive profiles was evaluated with latent transition analysis in a 10-week follow-up cohort. Confirmatory factor analysis (CFA) was carried out to investigate if cognitive profiles represent a unidimensional structure. A 4-profile solution was obtained from the discovery cohort and replicated in an independent cohort. It comprised of a "less-impaired" cognitive subtype, 2 subtypes with "intermediate cognitive impairment" differentiated by executive function performance, and a "globally impaired" cognitive subtype. This solution showed relative stability across time. CFA revealed that cognitive profiles are better explained by distinct meaningful profiles than a severity linear continuum. Associations between profiles and negative symptoms were observed. The subtyping of schizophrenia patients based on cognitive performance and its associations with symptomatology may aid phenotype refinement, mapping of specific biological mechanisms, and tailored clinical treatments.

Cross-cultural comparison of theory of mind deficits in patients with schizophrenia from China and Denmark: different aspects of ToM show different results

Introduction: Theory of mind (ToM) has been established as one of the most investigated and pronounced social cognitive deficits in schizophrenia. Yet, knowledge on whether measures of ToM can be used and compared across cultures is sparse. In this study, we used two simple, non-verbal ToM tests in patients with schizophrenia and non-clinical controls from China and Denmark to investigate whether culture has an impact on ToM performance.Methods: Sixty-six patients with schizophrenia (35 Chinese) and 67 matched non-clinical controls (38 Chinese) from China and Denmark were tested with Brünés Picture Sequencing Task and Animated Triangles Task. We compared three models for each outcome variable in order to investigate which model best fitted the data: the first model included group (controls, patients) as a predictor variable, the second included group and nationality (Chinese, Danish), and the third included both predictors and their interaction.Results: On most ToM subtests, culture seemed to play a role. Only performance on Brüne's 1st order ToM were best described as similar in both countries. The second model had the best fit for most of the subtests indicating that the difference between patients and controls in China and Denmark, respectively, is similar.Conclusions: Caution to cultural differences should be taken when comparing ToM in Asian and Western patients with schizophrenia as well as healthy individuals.

Corticolimbic brain anomalies are associated with cognitive subtypes in psychosis: A longitudinal study

Background.

Earlier studies examining structural brain abnormalities associated with cognitively derived subgroups were mainly cross-sectional in design and had mixed findings. Thus, we obtained cross-sectional and longitudinal data to characterize the extent and trajectory of brain structure abnormalities underlying distinct cognitive subtypes (“preserved,” “deteriorated,” and “compromised”) seen in psychotic spectrum disorders.

Methods.

Data from 364 subjects (225 patients with psychotic conditions and 139 healthy controls) were first used to determine the relationship of cognitive subtypes with cross-sectional measures of subcortical volume and cortical thickness. To probe neurodevelopmental abnormalities, brain structure laterality was examined. To examine whether neuroprogressive abnormalities persist, longitudinal brain structural changes over 5 years were examined within a subset of 101 subjects. Subsequent discriminant analysis using the identified brain measures was performed on an independent subject group.

Results.

Cross-sectional comparisons showed that cortical thinning and limbic volume reductions were most widespread in “deteriorated” cognitive subtype. Laterality comparisons showed more rightward amygdala lateralization in “compromised” than “preserved” subtype. Longitudinal comparisons revealed progressive hippocampal shrinkage in “deteriorated” compared with healthy controls and “preserved” subtype, which correlated with worse negative symptoms, cognitive and psychosocial functioning. Post-hoc discrimination analysis on an independent group of 52 subjects using the identified brain structures found an overall accuracy of 71% for classification of cognitive subtypes.

Conclusion.

These findings point toward distinct extent and trajectory of corticolimbic abnormalities associated with cognitive subtypes in psychosis, which can allow further understanding of the biological course of cognitive functioning over illness course and with treatment.

Increased Peripheral Interleukin 10 Relate to White Matter Integrity in Schizophrenia

Background: Schizophrenia is characterized by the disruption of microstructural white matter (WM) integrity, while the pathogenesis remains unclear. Inflammation has been associated with the WM pathology in schizophrenia. Interleukin 10 (IL-10) has been proven to be related to schizophrenia in both animal and human models. The aim of this study was to explore whether peripheral IL-10 was associated with microstructural WM integrity in schizophrenia.

Methods: A total of 47 patients with schizophrenia (SZ) and 49 healthy controls (HC) underwent diffusion tensor imaging and venous blood sampling. Tract-based spatial statistics was conducted to explore the differences in fractional anisotropy (FA), radial diffusivity (RD), mean diffusivity (MD), and axial diffusivity (AD) between patients and controls. A quantitative chemiluminescence assay was performed to measure peripheral IL-10 levels. General linear regression analysis using a stepwise method was applied to examine the relationship between peripheral IL-10 and diffusion measures.

Results: Compared with the HC, peripheral IL-10 levels were higher and a significant reduction of FA and AD, and increase of RD and MD were observed in SZ (corrected p < 0.05). A regression analysis revealed that peripheral IL-10 was negatively correlated with FA in the right posterior thalamic radiation and left inferior fronto-occipital fasciculus, in SZ (β = -0.51, p = 0.01; β = -0.47, p = 0.02, respectively) but not in HC (β = -0.01, p = 0.95; β = -0.003, p = 0.98, respectively), and the differences in regression curves were significant (z = 2.50, p = 0.01; z = 2.37, p = 0.02, respectively). IL-10 was negatively connected with MD in the right parietal arcuate fasciculus (β = -0.40, p = 0.048) and body of the corpus callosum (β = -0.43, p = 0.03) in SZ, while not in HC. The magnitude of correlation in the patient and control group was different (z = 2.48, p = 0.01 and z = 2.61, p < 0.01, respectively). In addition, IL-10 was positively correlated with RD in the right parietal arcuate fasciculus in patients (β = 0.45, p = 0.04) but not in HC (β = 0.26, p = 0.94), but the correlation coefficients were not significant (z = 0.98, p = 0.32).

Conclusion: Our findings demonstrated that elevated peripheral IL-10 levels were associated with the disruption of microstructural WM integrity in schizophrenia, supporting the notion that inflammation plays a regulatory role in the pathology of microstructural WM and is associated with schizophrenia.

Montreal Cognitive Assessment as a screening instrument for cognitive impairments in schizophrenia

BACKGROUND

Cognitive impairment is one of the core features of schizophrenia. For its evaluation, current clinical practice relies on detailed neuropsychological batteries which require trained testers and considerable amount of time to administer. Therefore, a brief and reliable screening tool for identification of overall cognitive impairment prior to a detailed comprehensive neurocognitive assessment is needed in a busy clinical setting. This study evaluates the clinical utility of the Montreal Cognitive Assessment (MoCA) in detecting cognitive impairments in schizophrenia and its relationship with functional outcome and demographic characters.

METHODS

The MoCA, the Brief Assessment of Cognition in Schizophrenia (BACS), and the Brief UCSD Performance-based Skills Assessment (UPSA-B) were administered to 64 patients with schizophrenia. Mild and severe cognitive impairments were defined as BACS Z-score (calculated with the age and gender adjustments using previously published local norm data) of one or two standard deviations below the mean, respectively.

RESULTS

The results showed that the MoCA was significantly correlated with BACS (r=.61, p<.001) and sensitive to detect both mild (AUC=0.82, p<.001) and severe (AUC=0.81, p<.001) cognitive impairments in schizophrenia. The MoCA was significantly correlated with UPSA-B score (r=.51, p<.001), and accounted for significant additional variance in UPSA-B score beyond the BACS.

CONCLUSION

These findings indicate that MoCA is a useful bedside cognitive screening instrument for people with schizophrenia.

The Chinese Version of the Brief Assessment of Cognition in Schizophrenia: Data of a Large-Scale Mandarin-Speaking Population

Objective

The Brief Assessment of Cognition in Schizophrenia (BACS) is a cognitive assessment tool used to measure the broad aspects of cognition that are most frequently impaired in patients with schizophrenia. This study aims to develop the normative data of the Chinese version of the BACS among the Mandarin-speaking population.

Method

This cross-sectional study included 382 healthy participants (age range: 19-79 years; mean age: 48.0 ± 16.7 years, 47.6% men) in Taiwan, who were evaluated with the BACS. Means and standard deviations of subtests and composite scores were arranged by age group and gender. The Z-scores calculated based on the U.S. norms were compared to our scores based on the norms established in this study.

Results

The raw scores of all the BACS tests (verbal memory, digit sequencing, token motor test, verbal fluency, symbol coding, and Tower of London) were negatively correlated with participants' age. Women were superior to men in verbal memory, but inferior to them in executive function. Furthermore, applying the U.S. norms of the BACS to determine the performance of the Chinese BACS results in bias with regard to verbal memory, token motor test, verbal fluency, symbol coding, Tower of London and composite score.

Conclusions

These findings demonstrate that directly applying western cognitive norms to a Mandarin-speaking population can cause biased interpretations. The results of this study can be an important reference for clinical settings and research related to cognitive assessments in Mandarin-speaking Chinese populations.

Affective symptoms in schizophrenia are strongly associated with neurocognitive deficits indicating disorders in executive functions, visual memory, attention and social cognition

The aim of this study was to assess the neurocognitive correlates of affective symptoms in schizophrenia. Towards this end, 40 healthy controls and 80 schizophrenia patients were investigated with six tests of the Cambridge Neuropsychological Test Automated Battery (CANTAB), assessing spatial working memory, paired-association learning, one touch stocking, rapid visual information (RVP), emotional recognition test and intra/extradimensional set shifting. The Hamilton Depression (HDRS) and Anxiety (HAMA) Rating Scales and the Calgary Depression Scale for Schizophrenia (CDSS) as well as the Positive and Negative Syndrome Scale (PANSS) were also used. There were highly significant associations between all 6 CANTAB tests and HDRS, HAMA and CDSS (except RVP) scores. The most significant items associating with neurocognitive impairments in schizophrenia were self-depreciation (CDSS), fatigue, psychomotor retardation and agitation, psychic and somatic anxiety (HDRS), fears, cognitive symptoms, somatic-muscular, genito-urinary and autonomic symptoms and anxious behavior (HAMA). The selected HDRS and HAMA symptoms indicate fatigue, fears, anxiety, agitation, retardation, somatization and subjective cognitive complaints (SCC) and are therefore labeled "FAARS". Up to 28.8% of the variance in the 6 CANTAB measurements was explained by FAARS, which are better predictors of neurocognitive impairments than the PANSS negative subscale score. Neurocognitive deficits in schizophrenia are best predicted by FAARS combined with difficulties in abstract thinking. In conclusion, depression and anxiety symptoms accompanying the negative and positive symptoms of schizophrenia are associated with neurocognitive deficits indicating disorders in executive functions, attention, visual memory, and social cognition. Neurocognitive deficits in schizophrenia reflect difficulties in abstract thinking and FAARS, including subjective cognitive complaints.

Establishing the Brief Assessment of Cognition - Short form

The study aims to identify and validate a parsimonious subset of tests in the commonly used Brief Assessment of Cognition in Schizophrenia (BACS) that allows the evaluation of global cognitive ability. Several permutations of subtests from the BACS were examined to identify the best subset of tests to compose the short form measure. The Brief Assessment of Cognition-Short Form (BAC-SF) was evaluated for convergent validity in healthy and psychiatric samples (N = 3718). Verbal Memory, Digit Sequencing, and Symbol Coding subtests were found to best summarize the variance of composite scores in both Asian and US Norming samples (r = 0.91) indicating that BAC-SF is an appropriate approximation of cognitive deficits. Test re-test reliability of the BAC-SF was adequate (Intraclass Correlation Coefficient (ICC) = 0.73) and showed sufficient separation between healthy controls and schizophrenia (Average Predictive Accuracy = 79.9%; replication = 76.5%). Findings indicate that the BAC-SF an could be used as a cognitive screener for large-scale clinical and epidemiological studies. The short form does not replace the need for comprehensive neuropsychological batteries purposed for detailed neuropsychological and clinical investigation of cognitive function. Further replication of the construct might be necessary in other clinical populations.