Course of cognitive functioning during the stabilization phase of schizophrenia

Effects of the number of hospitalizations on cognitive function in Japanese patients with stable schizophrenia

BACKGROUND

The present study aimed to determine whether the number of hospitalizations in schizophrenia patients is associated with reduced cognitive performance, which may in turn imply that recurrences indirectly lead to a worsening in the disorder's progression.

METHODS

Cognitive performance in stable schizophrenia patients was assessed using the Brief Assessment of Cognition in Schizophrenia, Japanese-language version, on 30 patients who had not experienced any hospitalizations (G0), 57 patients who had experienced only one hospitalization (G1), 47 patients with two hospitalizations (G2), and 59 patients with three or more hospitalizations (G3).

RESULTS

Significant differences in motor function and attention and processing speed were found between patients with G0 and those with G1. Significant differences in working memory and verbal fluency were found between patients with G1 and those with G2. Patients with G3 performed even more poorly in comparison with those with G1, showing deficits in verbal memory, working memory, executive function, and composite score. The patients with G3 displayed a greater range of impairment and demonstrated deficits in executive function compared with patients with G2. Finally, G2 and G3 performed more poorly than G0, with deficits in the various cognitive areas.

CONCLUSION

The number of hospitalizations predicted cognitive performance, which suggests that relapse or recurrence may have a long-term neuropsychological impact. Prospective follow-up studies must be completed to explore this effect further because better treatment adherence may have a protective effect on neurocognitive function.

Characterising the structure of cognitive heterogeneity in schizophrenia spectrum disorders. A systematic review and narrative synthesis

The aim of the present review was to systematically summarise our current understanding of the structure of the cognitive heterogeneity that exists within schizophrenia spectrum disorder (SSD). Fifty-two relevant studies were identified from January 1980 to March 2019 that investigated cognitive subgroups within SSD. Twenty-five studies employed classification criteria based on current neuropsychological function, 14 studies employed various data-driven subgrouping methodologies and 13 studies investigated putative cognitive symptom trajectories. Despite considerable methodological variability, three distinct cognitive subgroups reliability emerged; a relatively intact cognitive subgroup characterised by high cognitive performance, an intermediate cognitive subgroup defined by mixed or moderate levels of cognitive function/dysfunction and a globally impaired subgroup characterised by severe cognitive deficits. Whilst preliminary evidence suggests that these subgroups may have further investigative relevance in and of themselves, additional research is required and discussed. A set of reporting guidelines are also presented to overcome the methodological inconsistencies identified in the reviewed literature.

NMDA Receptor Model of Antipsychotic Drug-Induced Hypofrontality

Schizophrenia is a chronic mental disease, affecting around 1% of the general population. Schizophrenia is characterized by productive, negative, affective, and disorganization symptoms, and cognitive deficits. Cognitive deficits prevail in most of the schizophrenia patients and are one of the most disabling symptoms. They usually occur before the acute episode of the disease and tend to become chronic with no satisfactory treatment from antipsychotic drugs. Because of their early manifestation in patients’ lives, cognitive deficits are suggested to be the primary symptom of schizophrenia. The pathogenesis of cognitive deficits in schizophrenia is not fully understood. They are linked with hypofrontality, which is a decrease in blood flow and glucose metabolism in the prefrontal lobe of schizophrenia-suffering patients. Hypofrontality is linked with disturbances of the corticolimbothalamic circuit, important for cognition and memory in humans. The circuit consists of a group of neuroanatomic structures and hypothetically any disturbance in them may result in cognitive deficits. We present a translational preclinical model of understanding how antipsychotic medication may decrease the N-methyl-D-aspartic acid (NMDA) receptors’ activity and produce dysfunctions in the corticolimbothalamic circuit and hypofrontality. From several pharmacological experiments on rats, including mainly our own recent findings, we collected data that suggest that antipsychotic medication may maintain and escalate hypofrontality in schizophrenia, decreasing NMDA receptor activity in the corticolimbothalamic circuit in the human brain. We discuss our findings within the literature of the subject.

State-dependent microstructural white matter changes in drug-naïve patients with first-episode psychosis

BACKGROUND

Diffusion tensor imaging (DTI) studies have consistently shown white matter (WM) microstructural abnormalities in schizophrenia. Whether or not such alterations could vary depending on clinical status (i.e. acute psychosis v. remission) remains to be investigated.

METHODS

Twenty-five treatment-naïve first-episode psychosis (FEP) patients and 51 healthy-controls (HC) underwent MRI scanning at baseline. Twenty-one patients were re-scanned as soon as they achieved sustained remission of symptoms; 36 HC were also scanned twice. Rate-of-change maps of longitudinal DTI changes were calculated for in order to examine WM alterations associated with changes in clinical status. We conducted voxelwise analyses of fractional anisotropy (FA) and trace (TR) maps.

RESULTS

At baseline, FEP presented reductions of FA in comparison with HC [p < 0.05, false-discovery rate (FDR)-corrected] affecting fronto-limbic WM and associative, projective and commissural fasciculi. After symptom remission, patients showed FA increase over time (p < 0.001, uncorrected) in some of the above WM tracts, namely the right anterior thalamic radiation, right uncinate fasciculus/inferior fronto-occipital fasciculus, and left inferior fronto-occipital fasciculus/inferior longitudinal fasciculus. We also found significant correlations between reductions in PANSS scores and FA increases over time (p < 0.05, FDR-corrected).

CONCLUSIONS

WM changes affecting brain tracts critical to the integration of perceptual information, cognition and emotions are detectable soon after the onset of FEP and may partially reverse in direct relation to the remission of acute psychotic symptoms. Our findings reinforce the view that WM abnormalities in brain tracts are a key neurobiological feature of acute psychotic disorders, and recovery from such WM pathology can lead to amelioration of symptoms.

Lifetime psychopathological dimensions, cognitive impairment and functional outcome in psychosis

Psychopathological symptoms and cognitive impairment are related to psychosocial functioning. However, the nature of the association of cognitive impairment with psychosocial functioning still remains under scrutiny. We aimed to examine the relationships of premorbid adjustment, lifetime psychopathological dimensions, and cognitive performance with the typical level of psychosocial functioning during the previous year. We assessed ninety patients with schizophrenia spectrum disorders and affective disorders with psychotic symptoms to collect data on premorbid adjustment, lifetime psychopathological dimensions, cognitive performance and psychosocial functioning. Sixty-five healthy volunteers were included as controls. Pearson's correlations and hierarchical regression analyses were performed to ascertain to what extent the aforementioned variables predicted psychosocial functioning. Functional domains were significantly correlated with most of the premorbid features, lifetime psychopathological dimensions and cognitive domains. However, lifetime negative symptoms were the best predictors of psychosocial functioning in the hierarchical regression analyses (explaining between 47 and 64% of the variance). For psychosocial outcome in patients with psychoses, lifetime negative symptoms showed a stronger predictive validity than cognitive impairment or premorbid adjustment.

Neurocognition and Duration of Psychosis: A 10-year Follow-up of First-Episode Patients

A substantial proportion of schizophrenia-spectrum patients exhibit a cognitive impairment at illness onset. However, the long-term course of neurocognition and a possible neurotoxic effect of time spent in active psychosis, is a topic of controversy. Furthermore, it is of importance to find out what predicts the long-term course of neurocognition. Duration of untreated psychosis (DUP), accumulated time in psychosis the first year after start of treatment, relapse rates and symptoms are potential predictors of the long-term course. In this study, 261 first-episode psychosis patients were assessed neuropsychologically on one or more occasions. Patients were tested after remission of psychotic symptoms and reassessed 1, 2, 5, and 10 years after inclusion. The neurocognitive battery consisted of California Verbal Learning Test, Wisconsin Card Sorting Test, Controlled Oral Word Association Task, Trail Making A and B, and Finger Tapping. We calculated a composite score by adding the z-scores of 4 tests that were only moderately inter-correlated, not including Finger Tapping. Data were analyzed by a linear mixed model. The composite score was stable over 10 years. No significant relationship between psychosis before (DUP) or after start of treatment and the composite score was found, providing no support for the neurotoxicity hypothesis, and indicating that psychosis before start of treatment has no significant impact on the course and outcome in psychosis. We found no association between symptoms and the neurocognitive trajectory. Stable remission during the first year predicted neurocognitive functioning, suggesting that the early clinical course is a good predictor for the long-term course.

Long-term trajectories of cognitive deficits in schizophrenia: A critical overview

BACKGROUND

Cognitive disturbances are widely pronounced in schizophrenia and schizophrenia spectrum disorders. Whilst cognitive deficits are well established in the prodromal phase and are known to deteriorate at the onset of schizophrenia, there is a certain discrepancy of findings regarding the cognitive alterations over the course of the illness.

METHODS

We bring together the results of the longitudinal studies identified through PubMed which have covered more than 3 years follow-up and to reflect on the potential factors, such as sample characteristics and stage of the illness which may contribute to the various trajectories of cognitive changes.

RESULTS

A summary of recent findings comprising the changes of the cognitive functioning in schizophrenia patients along the longitudinal course of the illness is provided. The potential approaches for addressing cognition in the course of schizophrenia are discussed.

CONCLUSIONS

Given the existing controversies on the course of cognitive changes in schizophrenia, differentiated approaches specifically focusing on the peculiarities of the clinical features and changes in specific cognitive domains could shed light on the trajectories of cognitive deficits in schizophrenia and spectrum disorders.

A longitudinal study of cognitive functioning in schizophrenia: clinical and biological predictors

BACKGROUND

Cognitive deficits are a central feature of schizophrenia but it is not certain how cognitive functioning changes over time. The purpose of this prospective longitudinal study was to determine the temporal change of cognitive functioning and the predictors of cognitive performance from among demographic, clinical, and biological variables.

METHODS

Participants were individuals with schizophrenia or schizoaffective disorder whose cognitive functioning was assessed at multiple time points with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). At the baseline visit participants had a blood sample drawn from which C-reactive protein, antibodies to Herpes Simplex Virus type 1, and selected genetic polymorphisms were measured. Repeated measures linear regression was used to determine whether cognitive measures changed over time and which variables predicted cognitive performance.

RESULTS

The sample consisted of 132 participants, mean age 43.7 years at baseline, who received a median of 3 cognitive assessments over a period averaging 2.8 years. The RBANS Total score and Language index showed no statistically significant temporal change; performance on two indices, Immediate Memory and Attention, showed modest but statistically significant improvements (gains of 0.89±0.33 and 0.76±0.29 points per year, respectively); Visuospatial/Constructional performance showed a modest but statistically significant decline (of 0.80±0.25 points per year). Few variables predicted cognitive performance; however greater psychiatric symptom severity was associated with worse cognitive performance for most cognitive measures.

CONCLUSIONS

Cognitive functioning in middle-aged persons with schizophrenia showed an absence of decline for most measures and modest gains in some measures.

The global cognitive impairment in schizophrenia: consistent over decades and around the world

OBJECTIVE

Schizophrenia results in cognitive impairments as well as positive, negative, and disorganized symptomatology. The present study examines the extent to which these cognitive deficits are generalized across domains, potential moderator variables, and whether the pattern of cognitive findings reported in schizophrenia has remained consistent over time and across cultural and geographic variation.

METHOD

Relevant publications from 2006 to 2011 were identified through keyword searches in PubMed and an examination of reference lists. Studies were included if they (1) compared the cognitive performance of adult schizophrenia patients and healthy controls, (2) based schizophrenia diagnoses on contemporary diagnostic criteria, (3) reported information sufficient to permit effect size calculation, (4) were reported in English, and (5) reported data for neuropsychological tests falling into at least 3 distinct cognitive domains. A set of 100 non-overlapping studies was identified, and effect sizes (Hedge's g) were calculated for each cognitive variable.

RESULTS

Consistent with earlier analyses, patients with schizophrenia scored significantly lower than controls across all cognitive tests and domains (grand mean effect size, g=-1.03). Patients showed somewhat larger impairments in the domains of processing speed (g=-1.25) and episodic memory (g=-1.23). Our results also showed few inconsistencies when grouped by geographic region.

CONCLUSIONS

The present study extends findings from 1980 to 2006 of a substantial, generalized cognitive impairment in schizophrenia, demonstrating that this finding has remained robust over time despite changes in assessment instruments and alterations in diagnostic criteria, and that it manifests similarly in different regions of the world despite linguistic and cultural differences.

Working memory training in patients with chronic schizophrenia: a pilot study

Background. There is evidence that patients with schizophrenia suffer from decline in working memory performance with consequences for psychosocial outcome. Objective. To evaluate the efficacy of a computerized working memory training program (BrainStim) in patients with chronic schizophrenia. Methods. Twenty-nine inpatients with chronic schizophrenia were assigned to either the intervention group receiving working memory training (N = 15) or the control group without intervention (N = 14). Training was performed four times a week for 45 minutes during four weeks under neuropsychological supervision. At baseline and followup all participants underwent neuropsychological testing. Results. Pre-post comparisons of neuropsychological measures showed improvements in visual and verbal working memories and visual short-term memory with small and large effect sizes in the intervention group. In contrast, the control group showed decreased performance in verbal working memory and only slight changes in visual working memory and visual and verbal short-term memories after 4 weeks. Analyses of training profiles during application of BrainStim revealed increased performance over the 4-week training period. Conclusions. The applied training tool BrainStim improved working memory and short-term memory in patients with chronic schizophrenia. The present study implies that chronic schizophrenic patients can benefit from computerized cognitive remediation training of working memory in a clinical setting.

Cognitive inhibition and quality of life in schizophrenia: a pilot study

AIM

To compare cognitive inhibition and quality of life in patients with schizophrenia and healthy controls.

METHODS

Ten patients with schizophrenia were compared to 10 healthy controls, matched for age, sex, and educational level. Cognitive inhibition was examined by: 1) access to relevant information (Reading with distraction task), 2) suppression of no longer relevant information (Trail Making Test), and 3) restraint of cognitive resources to relevant information (Stroop Test, Hayling Sentence Completion Test, Go/No-Go Test). Montgomery Asberg Depression Rating Scale, Positive and Negative Syndrome Scale, and Schizophrenia-Quality of Life scale (S-QoL) were also used.

RESULTS

Patients with schizophrenia showed a significant impairment in the suppression function of cognitive inhibition only, in comparison to the control group. Their access and restraint functions of cognitive inhibition were preserved. No relationship between quality of life and cognitive inhibition was found in patients with schizophrenia.

CONCLUSIONS

During the stabilization phase of schizophrenia, the ability to inhibit neutral information access to working memory, and to restrain and suppress irrelevant information may not impair the patient's capacity to respond adequately to stressful situations, and thus would do not impact their quality of life.

Negative symptoms and executive function in schizophrenia: does their relationship change with illness duration?

BACKGROUND

Negative symptoms and cognitive dysfunction are of crucial functional and prognostic importance in schizophrenia. However, the nature of the relationship between them and the factors that may influence it have not been well established.

AIMS

To investigate whether the relationship between negative symptoms and executive function changes according to the duration of illness in schizophrenia.

METHODS

The Positive and Negative Syndrome Scale was used to assess psychopathology and the Wisconsin Card Sorting Test (WCST) to evaluate executive function in a sample of 200 schizophrenic patients who were classified in 3 groups according to their duration of illness: up to 5 years (short duration group), 6-20 years (intermediate duration group) and over 20 years of illness (long duration group).

RESULTS

Medium-sized correlations were found between negative symptoms and WCST performance as assessed by the number of completed categories in all 3 groups. However, differences were found according to the duration of schizophrenia. For patients in the short duration group, negative symptoms correlated with WCST nonperseverative errors, but for those in the long duration group the correlation was with perseverative errors.

CONCLUSION

We found a differential relationship between negative and cognitive symptoms in different stages of schizophrenia. Illness duration should be considered when studying the relationship between negative symptoms and cognition.

Specificity of jumping to conclusions and attributional biases: a comparison between patients with schizophrenia, depression, and anorexia nervosa

INTRODUCTION

The knowledge of the specificity of cognitive biases in psychiatric disorders is important in order to develop disorder-specific cognitive models and therapies. This cross-sectional study aimed to investigate the specificity of jumping to conclusions (JTC) and attributional biases (AB) for patients with schizophrenia.

METHODS

Twenty patients with paranoid schizophrenia were compared with patients with depression (n=20) and with anorexia nervosa (n=15) and nonclinical controls (n=55). All participants were administered a modified version of the beads task (JTC), a revised German version of the Internal, Personal, and Situational Attributions Questionnaire (AB), and several symptom and neurocognitive measures.

RESULTS

The proportion of patients with JTC bias in the schizophrenia group was, at the descriptive level, higher than in the depression and the anorexia groups. Regarding AB, the schizophrenia group showed a significantly stronger externalising but not personalising bias than the clinical control groups. Neither JTC nor attributional biases were significantly associated with delusions in general or persecutory delusion.

CONCLUSIONS

We found evidence for the specificity of an externalising bias for paranoid schizophrenia. Concerning JTC bias the evidence was less clear. Whether the modification of those biases through psychological interventions would have an effect on psychopathology should be investigated in the context of clinical trials.

Executive function needs to be targeted to improve social functioning with Cognitive Remediation Therapy (CRT) in schizophrenia

While the role of impaired cognition in accounting for functional outcome in schizophrenia is generally established, the relationship between cognitive and functional change in the context of treatments is far from clear. The current paper tries to identify which cognitive changes lead to improvements in daily functioning among persons with chronic schizophrenia who had current negative symptoms and evidenced neuropsychological impairments. In a previous work, Cognitive Remediation Therapy (CRT) was compared with a control therapy, involving similar length of therapist contact but different targets. At the end of treatment, CRT conferred a benefit to people with schizophrenia in cognition and functioning [Schizophrenia Research, 87 (2006) 323-331]. Subsequently, analyses of covariance (ANCOVA) were conducted with baseline and cognitive change scores as covariates to test whether cognitive change predicted change in functioning. Additionally, statistical tests to establish the mediation path with significant variables were performed. Although verbal memory, but not executive functioning, was associated with functioning at baseline, it was the improvement in executive functioning that predicted improved daily functioning. Verbal memory played a mediator role in the change process. Consequently, in order to improve daily functioning with CRT, executive function still needs to be targeted in despite of multiple cognitive impairments being present.

Neurocognition and its influencing factors in the treatment of schizophrenia-effects of aripiprazole, olanzapine, quetiapine and risperidone

BACKGROUND

To examine influencing variables of neurocognition in patients with schizophrenia and to predict cognition during antipsychotic treatment.

METHODS

Data were obtained from patients with an acute episode of schizophrenia participating in two double-blind and one open label trial comparing the effects of different atypical antipsychotics on cognition. In total, 129 patients were enrolled in this analysis. Cognitive function was assessed at admission, week 4 and 8. Efficacy and tolerability were assessed weekly using the Positive and Negative Syndrome Scale (PANSS) and the Simpson Angus Sale (SAS). Patients were treated with aripirazole, olanzapine, quetiapine and risperidone. Regression analysis including mixed effect models was performed.

RESULTS

A significant improvement in all cognitive domains was observed from baseline to week 8. Regarding the antipsychotic treatment applied quetiapine seemed to achieve the most favourable cognitive improvement. Negative and depressive symptoms, the patient's age and the concomitant and antipsychotic treatment applied were observed to significantly influence and predict neurocognition.

CONCLUSION

The results may indicate that schizophrenia is a static disorder with trait and state dependent cognitive components especially in the memory domains. The influence of negative and depressive symptoms should be considered in daily clinical routine.

Factor structure of the neurocognitive tests: an application of the confirmative factor analysis in stabilized schizophrenia patients

The purpose of the present study was to identify the factor structure of neurocognitive tests used on schizophrenia patients by using the confirmative factor analysis, and to assess the factor score differences of schizophrenia patients and healthy controls. Comprehensive neurocognitive tests were administered to stabilized schizophrenia patients (N=114) and healthy controls (N=120). In the results of factor analyses on patients, the multifactorial-6-factor model, which included the speed of processing, working memory, verbal learning and memory, visual learning and memory, attention/vigilance, and reasoning/problem solving as suggested by the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS), showed the better goodness of fit than any of the other models tested. And assessing the group differences of factor scores, we found the patients performed worse than the controls in all factors, but the result showed meaningful variations of impairments across the cognitive factors. Our study identifies the six major domains with multifactorial structure of cognitive abilities in schizophrenia patients and confirms the distinctive impairment patterns of each cognitive domain. These results may have utility in better understanding the pathology of schizophrenia as well as in genetic studies.

What do we know about neuropsychological aspects of schizophrenia?

Application of a neuropsychological perspective to the study of schizophrenia has established a number of important facts about this disorder. Some of the key findings from the existing literature are that, while neurocognitive impairment is present in most, if not all, persons with schizophrenia, there is both substantial interpatient heterogeneity and remarkable within-patient stability of cognitive function over the long-term course of the illness. Such findings have contributed to the firm establishment of neurobiologic models of schizophrenia, and thereby help to reduce the social stigma that was sometimes associated with purely psychogenic models popular during parts of the 20th century. Neuropsychological studies in recent decades have established the primacy of cognitive functions over psychopathologic symptoms as determinants of functional capacity and independence in everyday functioning. Although the cognitive benefits of both conventional and even second generation antipsychotic medications appear marginal at best, recognition of the primacy of cognitive deficits as determinants of functional disability in schizophrenia has catalyzed recent efforts to develop targeted treatments for the cognitive deficits of this disorder. Despite these accomplishments, however, some issues remain to be resolved. Efforts to firmly establish the specific neurocognitive/neuropathologic systems responsible for schizophrenia remain elusive, as do efforts to definitively demonstrate the specific cognitive deficits underlying specific forms of functional impairment. Further progress may be fostered by recent initiatives to integrate neuropsychological studies with experimental neuroscience, perhaps leading to measures of deficits in cognitive processes more clearly associated with specific, identifiable brain systems.

Schizophrenia, "just the facts" 4. Clinical features and conceptualization

Although dementia praecox or schizophrenia has been considered a unique disease entity for the past century, its definitions and boundaries have continued to vary over this period. At any given time, the changing concept of schizophrenia has been influenced by available diagnostic tools and treatments, related conditions from which it most needs to be distinguished, extant knowledge and scientific paradigms. There is significant heterogeneity in the etiopathology, symptomatology, and course of schizophrenia. It is characterized by an admixture of positive, negative, cognitive, mood, and motor symptoms whose severity varies across patients and through the course of the illness. Positive symptoms usually first begin in adolescence or early adulthood, but are often preceded by varying degrees of negative and cognitive symptomatology. Schizophrenia tends to be a chronic and relapsing disorder with generally incomplete remissions, variable degrees of functional impairment and social disability, frequent comorbid substance abuse, and decreased longevity. Although schizophrenia may not represent a single disease with a unitary etiology or pathogenetic process, alternative approaches have thus far been unsuccessful in better defining this syndrome or its component entities. The symptomatologic, course, and etio-pathological heterogeneity can usefully be addressed by a dimensional approach to psychopathology, a clinical staging approach to illness course, and by elucidating endophenotypes and markers of illness progression, respectively. This will allow an approach to the deconstruction of schizophrenia into its multiple component parts and strategies to reconfigure these components in a more meaningful manner. Possible implications for DSM-V and ICD-11 definitions of schizophrenia are discussed.

Collaboration in outpatient antipsychotic drug treatment: analysis of potentially influencing factors

Knowledge of factors relevant for medication adherence and patient collaboration is still limited. Our study aims at exploring the contribution of a variety of factors to collaboration in outpatients with schizophrenia and schizoaffective disorder. We obtained self-rated and observer-rated data from 108 outpatients during an interview 6 months after hospital discharge. The compliance rating scale (CRS) classified 76% of the patients as collaborative. Factors related to the patient, illness, treatment, and social environment were analysed in two-step explorative correlation and regression analyses in order to determine their relative contribution to collaboration. Only trust in medication and lack of insight were associated with collaboration, and they accounted for 38% of the variance. Neither medication side effects nor neuropsychological functioning correlated with collaboration. The conceptualisation of medication adherence is complex, and there are a number of unresolved methodological problems. The data indicate that illness and treatment-related subjective attitudes may be more relevant than side effects, cognitive functioning or any sociodemographic variable.