Elsevier

Schizophrenia Research

Volume 72, Issue 1, 15 December 2004, Pages 41-51
Schizophrenia Research

Longitudinal studies of cognition and functional outcome in schizophrenia: implications for MATRICS

https://doi.org/10.1016/j.schres.2004.09.009Get rights and content

Abstract

It is generally accepted that cognitive deficits in schizophrenia are related to functional outcome. However, support for longitudinal relationships between cognition and functional outcome has not been as well documented. The current paper presents a review of 18 recently published longitudinal studies (minimum 6-month follow up) of the relationships between cognition and community outcome in schizophrenia. Results from these studies reveal considerable support for longitudinal associations between cognition and community outcome in schizophrenia. These studies demonstrate that cognitive assessment predict later functional outcome and provide a rationale for psychopharmacological interventions for cognitive deficits in schizophrenia. Although the relationships between cognition and community outcome are well-supported, it is clear that community functioning is also affected by a host of factors apart from cognition that are usually not considered in clinical trial studies (e.g., psychosocial rehabilitation and educational/vocational opportunities). In the second part of the paper, we consider intervening steps between cognitive performance measures and community outcome. These steps are apt to have important implications for clinical trials of cognition-enhancing agents in schizophrenia.

Section snippets

Longitudinal studies of cognition and community outcome in schizophrenia

For this review of the literature, we were primarily interested in longitudinal studies that examined the cognitive predictors of some aspect of community functioning. With this fairly specific goal in mind, we did not consider the cognitive predictors and correlates of rehabilitation success or performance on simulated tasks of interpersonal communication, as we have done in our previous reviews (Green, 1996, Green et al., 2000). We specifically selected studies that were not part of the

Mapping changes in cognitive performance measures onto changes in functional outcome

At the MATRICS meeting in April 2003 (see summary in Green et al., 2004), a key discussion point was whether changes in cognitive performance alone should be sufficient for a drug to receive approval from the U.S. Food and Drug Administration (FDA). On the one hand, improvement on a cognitive performance measure appears to be the most reliable and sensitive way to establish that a drug improves cognition. On the other hand, changes on cognitive performance measures alone may not be sufficient

Summary

In summary, we have documented rather consistent relationships between baseline assessments in schizophrenia and community functioning at a minimum of 6 months later. The cross-sectional relationships between cognition and functional outcome have been well established in previous reviews (Green, 1996, Green et al., 2000), and the demonstration of these longitudinal relationships in the current review indicates that cognitive performance at one point in time predicts community functioning at a

Acknowledgments

An earlier version of this paper was presented at the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Conference #1: Identifying Cognitive Targets and Establishing Criteria for Test Selection, Bethesda, MD. Support for this conference came from NIMH Contract MH22006 (S.R. Marder, P.I., M.F. Green, Co-P.I.)

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