A longitudinal analysis of memory in patients with schizophrenia

Computerized assessment of cognition in schizophrenia: Promises and pitfalls of CANTAB

Objective

Over the last decade, the Cambridge Neuropsychological Test Automated Battery (CANTAB), which comprises visuo-spatial tasks, has been utilized in cognitive studies of schizophrenia. A clear approach concerning the usage of CANTAB for the appraisal of neurocognitive dysfunction in schizophrenia is currently lacking.

Method

In this paper, we have first reviewed the overall applications of CANTAB and then evaluated methodological strengths and weaknesses of CANTAB as a neurocognitive battery for schizophrenia. We carried out a systematic search and assessment of studies where CANTAB was utilized to measure cognitive function in schizophrenia. We have also attempted to quantify the available data and perform a meta-analysis, but this approach turned out to be still premature.

Results

CANTAB has enabled researchers to highlight significant deficits affecting broad cognitive domains in schizophrenia, such as working memory, decision-making, attention, executive functions and visual memory. So far, the most consistent deficit observed with CANTAB testing has been attentional set-shifting, suggestive of fronto-striatal dysfunctions. In addition, preliminary evidence points towards the potential use of CANTAB to identify cognitive predictors of psychosocial functioning, to describe the relationships between symptoms and cognition, and to measure the impact of pharmacological agents on cognitive functioning.

Conclusion

CANTAB has been used successfully to highlight the range of visuo-spatial cognitive deficits in schizophrenia, producing similar results to those obtained with some traditional neuropsychological tests. Further studies validating the use of CANTAB following the standard set by Measurement And Treatment Research to Improve Cognition in Schizophrenia (MATRICS) are warranted.

Sex differences in the association between childhood adversities and schizotypal personality traits

Patients with psychosis report higher levels of adverse events in childhood. This relationship has not been extensively examined in healthy individuals who score highly on schizotypal personality traits. This study examined the association between different childhood traumas and psychosis-like traits in a general population sample, as well as differences in those links between men and women. Participants completed an online survey including measures of physical, emotional, and sexual abuse, and schizotypal personality traits. Results showed that the experience of emotional abuse was associated with a range of both positive and negative psychosis-like traits in both sexes. Sex differences emerged in the association between physical abuse and schizotypal personality traits. Although men reported more physical abuse in early life than women, this type of trauma was only associated with schizotypal traits in women and not in men. Additionally, women scored higher than men in sexual abuse; however, sexual abuse did not explicitly predict any schizotypal traits in the presence of the other two types of abuse. A simple linear or dose-response relationship between different types of trauma and psychosis-like traits was not supported. The importance of emotional abuse on schizotypy was highlighted in both sexes.

The clinical utility, reliability and validity of the Rivermead Behavioural Memory Test-Third Edition (RBMT-3) in Hong Kong older adults with or without cognitive impairments

This study examined the use of the Hong Kong version of the Rivermead Behavioral Memory Test-Third Edition (RBMT-3) for older adults, and by presenting the optimal cut-off scores for patients with cognitive impairments, and for a group of peers who have functional everyday cognition. Hundred older adults residing in community dwellings were recruited from three non-government organisations and completed the RBMT-3: 29 patients with mild to moderate dementia, 34 persons at risk for MCI, and 37 matched older adults with everyday functional cognition for a healthy control group (NC). The test has excellent inter-rater (ICC [2, 1] = 0.997), intra-rater (ICC [3, 1] = 0), and parallel version (ICC [3, 1] = 0.990) reliabilities, as well as satisfactory internal consistency (Cronbach's alpha: 0.643-0.832). The scores of the MCI group were significantly lower than those of NC group in four subtests. The optimal cut-off scaled scores of ≤ 41.5, ≤ 102.5, and ≤ 131.5 are suggested for the RBMT-3 to discriminate between patients with mild and moderate dementia, mild dementia and MCI, and MCI and NC, with sensitivities 73%, 100% and 94.1%, respectively. This version is useful to differentiate those with or without risk of cognitive impairments.

Working Memory in Unaffected Relatives of Patients With Schizophrenia: A Meta-Analysis of Functional Magnetic Resonance Imaging Studies

Working memory deficits, a core cognitive feature of schizophrenia may arise from dysfunction in the frontal and parietal cortices. Numerous studies have also found abnormal neural activation during working memory tasks in patients' unaffected relatives. The aim of this study was to systematically identify and anatomically localize the evidence for those activation differences across all eligible studies. Fifteen functional magnetic resonance imaging (fMRI) manuscripts, containing 16 samples of 289 unaffected relatives of patients with schizophrenia, and 358 healthy controls were identified that met our inclusion criteria: (1) used a working memory task; and (2) reported standard space coordinates. Activation likelihood estimation (ALE) identified convergence across studies. Compared to healthy controls, patients' unaffected relatives showed decreases in neural activation in the right middle frontal gyrus (BA9), as well as right inferior frontal gyrus (BA44). Increased activation was seen in relatives in the right frontopolar (BA10), left inferior parietal lobe (BA40), and thalamus bilaterally. These results suggest that the familial risk of schizophrenia is expressed in changes in neural activation in the unaffected relatives in the cortical-subcortical working memory network that includes, but is not restricted to the middle prefrontal cortex.

Emotional memory modulation in schizophrenia: an overview

OBJECTIVE

In healthy controls, the emotional charge of stimuli influences how well stimuli are remembered. Although patients with schizophrenia (SCZ) have deficits in memory and in emotional processing, studies on emotional memory modulation (EMM) in SCZ report contradictory results. The aim of this review was to investigate whether methodological differences could explain these contradictory results.

METHOD

We reviewed the literature to investigate whether task differences could explain these differences. Due to the methodological differences, a meta-analysis was not possible.

RESULTS

Fourteen studies were identified that used a total of 22 tasks to study EMM in patients with SCZ. Two-thirds of the tasks showed no differences in EMM between patients with SCZ and healthy controls. Differences in EMM were found more often when long-term compared to short-term memory was measured, when memory instructions were implicit instead of explicit and when stronger emotional stimuli were used. An overall memory deficit or the mode of retrieval was not related to EMM.

CONCLUSION

Deficits in EMM in long-term compared to short-term memory point toward impaired emotional modulation of memory consolidation. Reduced EMM on implicit, but not explicit, tasks suggests a deficit in unconsciously using emotional content to modulate memory.

A virtual reality-based vocational training system (VRVTS) for people with schizophrenia in vocational rehabilitation

Employment provides schizophrenic patients with a positive identity and hope. Cognitive impairments have been suggested to slow down the progress in work rehabilitation. The purpose of this study was to investigate the efficacy and effectiveness of VR as a cognitive intervention for enhancing vocational outcomes. 95 inpatients with schizophrenia were randomly assigned to a virtual reality-based vocational training group (VRG), a therapist-administered group (TAG) and a conventional group (CG). Twenty-five of them in each group had completed the study. Their performances were evaluated, before and after interventions, by Brief Neuropsychological Cognitive Examination, Digit Vigilance Test, Rivermead Behavioural Memory Test, Wisconsin Card Sorting Test (WCST) and Vocational Cognitive Rating Scale. Patients in the VRG were found to perform better than patients in the TAG and CG in cognitive functioning, as shown by the WCST-percentage of error (F (2, 72)=7.146, p<0.001) and the WCST-percentage of conceptual level response (F (2, 72)=8.722, p<0.001). The post-hoc test revealed that the VRG showed a better performance than both the TAG (p=0.03) and the CG (p<0.001) in the WCST-percentage of error. The VRG also showed a better performance than patients in both the TAG (p=0.01) and the CG (p<0.001) in the WCST-percentage of conceptual level response. The VRG also showed a better self-efficacy score than CG. Both VRG and TAG showed a better work performance as reflected by the on-site tests. Further studies on the use of VR in schizophrenia rehabilitation and for vocational success are discussed.

Psychiatric and demographic predictors of memory deficits in African Americans with schizophrenia: the moderating role of cultural mistrust

Although African Americans are overrepresented among schizophrenia diagnoses, assessments of memory deficits in schizophrenia often do not consider issues of race, ethnicity, and culture. Digit span testing (DST) is often used to assess memory problems associated with schizophrenia. The purpose of the current study was to examine the effects of psychiatric symptoms and demographic background on the DST performances of 128 African American schizophrenic patients. It was hypothesized that level of cultural mistrust would moderate the relationship of psychiatric and demographic variables to memory deficits. The study involved the secondary analysis of data from the Culturally-Sensitive Diagnostic Interview Research Project. Different models of the relationship among predictor variables in their impact on DST performance were tested via structural equation modeling (SEM); and the moderating effects of level of cultural mistrust were evaluated with the best SEM model. The results supported the hypothesis that level of cultural mistrust moderates the relationship among variables in the SEM model. Specifically, psychiatric symptoms negatively impacted DST performance in the low cultural mistrust group, but they had no significant association to the memory deficits of the high cultural mistrust group. The pattern of findings for the effects of psychiatric symptoms on DST performance is consistent with the view of cultural mistrust as an adaptive mechanism in African Americans. One implication is that cultural factors should be taken into account when assessing memory deficits in African Americans with schizophrenia.

Doubtful association of antipsychotic polypharmacy and high dosage with cognition in chronic schizophrenia

Despite consistent recommendations for antipsychotic monotherapy, antipsychotic polypharmacy (the use of two or more antipsychotic agents) and the administration of excessive doses (higher than 1000 mgr/day of chloropromazine equivalents) is a common practice in schizophrenia. The therapeutic and adverse effects of this practice are poorly studied, in particular with regards to the cognitive symptoms of the disease. In this cross-sectional study we investigated the cognitive effects of antipsychotic polypharmacy and excessive doses in 53 patients with chronic schizophrenia using non-verbal cognitive tasks involving speed of movement, memory and executive functions. No significant difference in performance scores was found between the groups under polypharmacy and monotherapy, or the groups receiving either excessive or normal doses of antipsychotics. Since these groups did not also differ in demographic, clinical, other pharmacologic parameters, in the relative anticholinergic potency of antipsychotics, or in intelligence scores, we raise doubts about the association of polypharmacy and excessive doses with non-verbal cognitive performance in chronic schizophrenia.

Genetics and intermediate phenotypes of the schizophrenia--bipolar disorder boundary

Categorization of psychotic illnesses into schizophrenic and affective psychoses remains an ongoing controversy. Although Kraepelinian subtyping of psychosis was historically beneficial, modern genetic and neurophysiological studies do not support dichotomous conceptualization of psychosis. Evidence suggests that schizophrenia and bipolar disorder rather present a clinical continuum with partially overlapping symptom dimensions, neurophysiology, genetics and treatment responses. Recent large scale genetic studies have produced inconsistent findings and exposed an urgent need for re-thinking phenomenology-based approach in psychiatric research. Epidemiological, linkage and molecular genetic studies, as well as studies in intermediate phenotypes (neurocognitive, neurophysiological and anatomical imaging) in schizophrenia and bipolar disorders are reviewed in order to support a dimensional conceptualization of psychosis. Overlapping and unique genetic and intermediate phenotypic signatures of the two psychoses are comprehensively recapitulated. Alternative strategies which may be implicated into genetic research are discussed.

Errorless learning and spaced retrieval techniques to relearn instrumental activities of daily living in mild Alzheimer's disease: A case report study

Previous studies on cognitive training in Alzheimer's disease (AD) were principally aimed at making patients learn items not related to functional needs. However, AD patients also experience difficulties with instrumental activities of daily living (IADL). The goal of the present multiple baseline case report study was to assess the preliminary efficacy and tolerability of an individualized cognitive training program using the errorless learning (EL) and spaced-retrieval (SR) techniques to relearn forgotten IADLs in mild AD. Following an exhaustive neuropsychological assessment, two participants received two training sessions per week during four weeks. Participant A was trained to use his voice mail and Participant B, to manage the messages from his answering machine. The results showed that the program was well tolerated and improved performance on the trained tasks. These ameliorations were maintained over a 5-week period. The effects of the training did not have any impact on global cognitive functions since the results on these measures remained relatively stable. This case report demonstrated preliminary efficacy of a new cognitive training program using EL and SR techniques tailored to the needs of AD patients. This is an important finding since the loss of these capacities alters autonomy in AD patients.

Working memory in siblings of schizophrenia patients

Working memory (WM) has hardly been explored in non-psychotic relatives of schizophrenic patients despite its potential suitability as a neurocognitive endophenotype. Indeed, WM modalities, components and processes have rarely been compared in the same group of relatives. The present study examined neurocognitive performance in healthy siblings of schizophrenic patients, including both spatial and verbal WM modalities and tests tapping maintenance (Spatial Span Backwards and CPT-IP d') and manipulative (Letters and Numbers Sequencing) WM processes.

METHODS

68 schizophrenia patients, 38 healthy siblings and 63 controls were assessed on IQ, attention, memory, WM, and executive functions. Cluster A symptoms were screened out in siblings and controls.

RESULTS

Siblings had an intermediate performance between that of schizophrenic patients and controls. They performed worse than controls on IQ, LNS, animal naming, backwards spatial span, phonemic fluency, numbers d', and forward spatial span.

DISCUSSION

Consistent with the WM literature in schizophrenia, both verbal and spatial WM differed significantly between siblings and controls, suggesting that WM deficits are modality independent. Our results failed to support the hypothesis that tests tapping WM manipulative processes heavily loading on DLFPC are quantitatively more impaired in relatives and, therefore, more sensitive to liability for schizophrenia. However, firm conclusions cannot be drawn until more studies assessing both maintenance and manipulative WM processes in relatives are available.

The Consortium on the Genetics of Schizophrenia: neurocognitive endophenotypes

The Consortium on the Genetics of Schizophrenia (COGS) is a 7-site collaboration that examines the genetic architecture of quantitative endophenotypes in families with schizophrenia. Here we review the background and rationale for selecting neurocognitive tasks as endophenotypic measures in genetic studies. Criteria are outlined for the potential of measures as endophenotypic vulnerability markers. These include association with illness, state independence (ie, adequate test-retest stability, adequate between-site reliability, impairments in patients not due to medications, impairments observed regardless of illness state), heritability, findings of higher rates in relatives of probands than in the general population, and cosegregation within families. The COGS required that, in addition, the measures be "neurocognitive" and thus linked to neurobiology and that they be feasible in multisite studies. The COGS neurocognitive assessment includes measures of attention, verbal memory, working memory, and a computerized neurocognitive battery that also includes facial processing tasks. Here we describe data demonstrating that these neurobehavioral measures meet criteria for endophenotypic candidacy. We conclude that quantitative neurocognitive endophenotypes need further evidence for efficacy in identifying genetic effects but have the potential of providing unprecedented insight into gene-environment interaction related to dimensions of brain and behavior in health and disease.