A Meta-Analysis of Cognitive Remediation for Schizophrenia: Methodology and Effect Sizes
01 May 2011-American Journal of Psychiatry (American Psychiatric Publishing Arlington, VA)-Vol. 168, Iss: 5, pp 472-485
TL;DR: Cognitive remediation benefits people with schizophrenia, and when combined with psychiatric rehabilitation, this benefit generalizes to functioning, relative to rehabilitation alone.
Abstract: Objective:Cognitive remediation therapy for schizophrenia was developed to treat cognitive problems that affect functioning, but the treatment effects may depend on the type of trial methodology adopted. The present meta-analysis will determine the effects of treatment and whether study method or potential moderators influence the estimates. Method:Electronic databases were searched up to June 2009 using variants of the key words “cognitive,” “training,” “remediation,” “clinical trial,” and “schizophrenia.” Key researchers were contacted to ensure that all studies meeting the criteria were included. This produced 109 reports of 40 studies in which ≥70% of participants had a diagnosis of schizophrenia, all of whom received standard care. There was a comparison group and allocation procedure in these studies. Data were available to calculate effect sizes on cognition and/or functioning. Data were independently extracted by two reviewers with excellent reliability. Methodological moderators were extracted th...
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TL;DR: Cognitive reserve provides an explanation for differences between individuals in susceptibility to age-related brain changes or pathology related to Alzheimer's disease, whereby some people can tolerate more of these changes than others and maintain function.
Abstract: The concept of cognitive reserve provides an explanation for differences between individuals in susceptibility to age-related brain changes or pathology related to Alzheimer's disease, whereby some people can tolerate more of these changes than others and maintain function. Epidemiological studies suggest that lifelong experiences, including educational and occupational attainment, and leisure activities in later life, can increase this reserve. For example, the risk of developing Alzheimer's disease is reduced in individuals with higher educational or occupational attainment. Reserve can conveniently be divided into two types: brain reserve, which refers to differences in the brain structure that may increase tolerance to pathology, and cognitive reserve, which refers to differences between individuals in how tasks are performed that might enable some people to be more resilient to brain changes than others. Greater understanding of the concept of cognitive reserve could lead to interventions to slow cognitive ageing or reduce the risk of dementia.
2,278 citations
University of Paris1, Ruhr University Bochum2, University of Cambridge3, University of California, Davis4, University of Massachusetts Dartmouth5, University of Paris-Sud6, University of Manchester7, University of Pennsylvania8, University of California, San Diego9, University of Oxford10, Utrecht University11, University of Zurich12, Heidelberg University13, King's College London14, University of Warwick15, Medical University of Vienna16, Newcastle University17, Emory University18
TL;DR: This article critically discusses the challenges and opportunities for improving cognition in individuals suffering from psychiatric disorders, highlighting the needs to characterize the cellular and cerebral circuits underpinning cognitive function and identify more effective treatments.
Abstract: Studies of psychiatric disorders have traditionally focused on emotional symptoms such as depression, anxiety and hallucinations. However, poorly controlled cognitive deficits are equally prominent and severely compromise quality of life, including social and professional integration. Consequently, intensive efforts are being made to characterize the cellular and cerebral circuits underpinning cognitive function, define the nature and causes of cognitive impairment in psychiatric disorders and identify more effective treatments. Successful development will depend on rigorous validation in animal models as well as in patients, including measures of real-world cognitive functioning. This article critically discusses these issues, highlighting the challenges and opportunities for improving cognition in individuals suffering from psychiatric disorders.
958 citations
TL;DR: The evidence that computerized cognitive training improves cognitive skills in older adults with normal cognition is systematically reviewed and meta-analyzed.
Abstract: Background
New effective interventions to attenuate age-related cognitive decline are a global priority. Computerized cognitive training (CCT) is believed to be safe and can be inexpensive, but neither its efficacy in enhancing cognitive performance in healthy older adults nor the impact of design factors on such efficacy has been systematically analyzed. Our aim therefore was to quantitatively assess whether CCT programs can enhance cognition in healthy older adults, discriminate responsive from nonresponsive cognitive domains, and identify the most salient design factors.
Methods and Findings
We systematically searched Medline, Embase, and PsycINFO for relevant studies from the databases' inception to 9 July 2014. Eligible studies were randomized controlled trials investigating the effects of ≥4 h of CCT on performance in neuropsychological tests in older adults without dementia or other cognitive impairment. Fifty-two studies encompassing 4,885 participants were eligible. Intervention designs varied considerably, but after removal of one outlier, heterogeneity across studies was small (I2 = 29.92%). There was no systematic evidence of publication bias. The overall effect size (Hedges' g, random effects model) for CCT versus control was small and statistically significant, g = 0.22 (95% CI 0.15 to 0.29). Small to moderate effect sizes were found for nonverbal memory, g = 0.24 (95% CI 0.09 to 0.38); verbal memory, g = 0.08 (95% CI 0.01 to 0.15); working memory (WM), g = 0.22 (95% CI 0.09 to 0.35); processing speed, g = 0.31 (95% CI 0.11 to 0.50); and visuospatial skills, g = 0.30 (95% CI 0.07 to 0.54). No significant effects were found for executive functions and attention. Moderator analyses revealed that home-based administration was ineffective compared to group-based training, and that more than three training sessions per week was ineffective versus three or fewer. There was no evidence for the effectiveness of WM training, and only weak evidence for sessions less than 30 min. These results are limited to healthy older adults, and do not address the durability of training effects.
Conclusions
CCT is modestly effective at improving cognitive performance in healthy older adults, but efficacy varies across cognitive domains and is largely determined by design choices. Unsupervised at-home training and training more than three times per week are specifically ineffective. Further research is required to enhance efficacy of the intervention.
Please see later in the article for the Editors' Summary
652 citations
Cites methods from "A Meta-Analysis of Cognitive Remedi..."
...First, all test results were combined to produce a single SMD per study, following established procedure [29]....
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TL;DR: This guideline takes a holistic approach, addressing all aspects of the care of people with schizophrenia and related disorders, not only correct diagnosis and symptom relief but also optimal recovery of social function, and uses a clinical staging model as a framework for recommendations regarding assessment, treatment and ongoing care.
Abstract: Objectives:This guideline provides recommendations for the clinical management of schizophrenia and related disorders for health professionals working in Australia and New Zealand. It aims to encou...
641 citations
Cites background from "A Meta-Analysis of Cognitive Remedi..."
...There is clear evidence for CBT for psychosis and cognitive remediation, with an emerging evidence base for other therapies (Lyman et al., 2014; Wykes et al., 2008, 2011)....
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...There is emerging evidence of associated improved real-world function (Wykes et al., 2011), but the outstanding issues for further research include the mechanisms of change and ensuring real-world transfer....
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TL;DR: This article posits that this emphasis on psychosis is a conceptual fallacy that has greatly contributed to the lack of progress in the understanding of this illness and hence has hampered the development of adequate treatments.
Abstract: Schizophrenia is currently classified as a psychotic disorder. This article posits that this emphasis on psychosis is a conceptual fallacy that has greatly contributed to the lack of progress in our understanding of this illness and hence has hampered the development of adequate treatments. Not only have cognitive and intellectual underperformance consistently been shown to be risk factors for schizophrenia, several studies have found that a decline in cognitive functioning precedes the onset of psychosis by almost a decade. Although the question of whether cognitive function continues to decline after psychosis onset is still debated, it is clear that cognitive function in schizophrenia is related to outcome and little influenced by antipsychotic treatment. Thus, our focus on defining (and preventing) the disorder on the basis of psychotic symptoms may be too narrow. Not only should cognition be recognized as the core component of the disorder, our diagnostic efforts should emphasize the changes in cognitive function that occur earlier in development. Putting the focus back on cognition may facilitate finding treatments for the illness before psychosis ever emerges.
639 citations
References
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TL;DR: In this article, the authors present a model for estimating the effect size from a series of experiments using a fixed effect model and a general linear model, and combine these two models to estimate the effect magnitude.
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9,769 citations
TL;DR: In this paper, the authors present a model for estimating the effect size from a series of experiments using a fixed effect model and a general linear model, and combine these two models to estimate the effect magnitude.
Abstract: Preface. Introduction. Data Sets. Tests of Statistical Significance of Combined Results. Vote-Counting Methods. Estimation of a Single Effect Size: Parametric and Nonparametric Methods. Parametric Estimation of Effect Size from a Series of Experiments. Fitting Parametric Fixed Effect Models to Effect Sizes: Categorical Methods. Fitting Parametric Fixed Effect Models to Effect Sizes: General Linear Models. Random Effects Models for Effect Sizes. Multivariate Models for Effect Sizes. Combining Estimates of Correlation Coefficients. Diagnostic Procedures for Research Synthesis Models. Clustering Estimates of Effect Magnitude. Estimation of Effect Size When Not All Study Outcomes Are Observed. Meta-Analysis in the Physical and Biological Sciences. Appendix. References. Index.
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