Elsevier

Schizophrenia Research

Volume 72, Issue 1, 15 December 2004, Pages 21-28
Schizophrenia Research

Cognitive deficits as treatment targets in schizophrenia

https://doi.org/10.1016/j.schres.2004.09.008Get rights and content

Abstract

Cognitive impairment has emerged as an important new target in schizophrenia therapeutics in light of evidence that cognitive deficits are critically related to the functional of disability that is characteristic of the illness. Evidence is briefly reviewed supporting the idea that the cognitive impairment in schizophrenia is an attractive target for therapeutic intervention including: (1) there is a characteristic pattern of cognitive deficits that occur with very high frequency; (2) the deficits are relatively stable over time; and (3) cognitive deficits are relatively independent of the symptomatic manifestations of the illness. Thus, cognitive impairment appears to be a well-defined, reliable and distinct dimension of the illness.

Section snippets

Cognitive deficits as treatment targets in schizophrenia

The recognition of cognitive impairment as a critical treatment target, reflected in two recent NIMH initiatives, Measurement and Treatment Research in Cognition in Schizophrenia (MATRICS) and Treatment Units for Research on Neurocognition in Schizophrenia (TURNS), marks an important turning point in schizophrenia therapeutics. Conceptually, the focus on cognition builds upon dimensional views of schizophrenia that have been articulated for over 30 years, most notably by Carpenter and

The level and pattern of impairment in schizophrenia

The level and pattern of cognitive impairment in schizophrenia has been documented using broad clinical neuropsychological batteries in dozens of studies in the last two decades. Although the specific details have varied slightly depending on sampling issues and measure selection, these studies have provided remarkably consistent evidence that schizophrenia involves a broad compromise of cognitive function on the order of 1.0–1.75 standard deviations below the normal mean, with some variability

The frequency of impairment

The clear evidence that cognitive impairment is a reliable feature of group data does not necessarily address the question of whether all patients with schizophrenia should be considered as potential recipients for a cognitive enhancing treatment. Note, such robust and reliable group mean differences between patients and controls could only arise if impairment was highly frequent among patients. However, the question remains whether impairment can be detected in all patients when considered at

The course of impairment

The vast majority of cognitive studies in schizophrenia prior to the last decade were conducted in chronically ill patient samples, typically drawn from long-term care inpatient facilities. This sampling bias raises the possibility that that the deficit pattern documented in the literature—and that summarized in the meta-analysis of Heinrichs and Zakanis—might reflect the impact of numerous potential adverse and uncontrolled variables including the impact of institutionalization, the possible

Independence from symptoms

The demonstration that the cognitive impairments of schizophrenia are largely independent of the symptomatic manifestations of the illness is a critical part of the rationale for developing specific treatments for cognition. That is, if cognitive impairment were directly caused by, or were secondary to, the other symptoms of the illness there would be no reason to advance cognition as a separate therapeutic target. Similarly, if cognitive impairment is simply another manifestation of the same

Back to the future

The evidence that the cognitive impairment of schizophrenia is a core feature of the disorder with a characteristic profile that is largely stable over time and largely independent of the clinical symptoms of the illness, yet importantly predictive of functional outcome is the evidence base that motivates the NIMH MATRICS initiative. This identification of cognition as a distinct therapeutic target marks an important turning point in schizophrenia therapeutics by focusing treatment development

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