Neurocognition is moderately to severely impaired in patients with schizophrenia. However, the factor structure of the various neurocognitive deficits, the relationship with symptoms and other variables, and the minimum amount of testing required to determine an adequate composite score has not been determined in typical patients with schizophrenia. An 'all-comer' approach to cognition is needed, as provided by the baseline assessment of an unprecedented number of patients in the CATIE (Clinical Antipsychotic Trials of Intervention Effectiveness) schizophrenia trial. From academic sites and treatment providers representative of the community, 1493 patients with chronic schizophrenia were entered into the study, including those with medical comorbidity and substance abuse. Eleven neurocognitive tests were administered, resulting in 24 individual scores reduced to nine neurocognitive outcome measures, five domain scores and a composite score. Despite minimal screening procedures, 91.2% of patients provided meaningful neurocognitive data. Exploratory principal components analysis yielded one factor accounting for 45% of the test variance. Confirmatory factor analysis showed that a single-factor model comprised of five domain scores was the best fit. The correlations among the factors were medium to high, and scores on individual factors were very highly correlated with the single composite score. Neurocognitive deficits were modestly correlated with negative symptom severity (r ¼ 0.13-0.27), but correlations with positive symptom severity were near zero (ro0.08). Even in an 'all-comer' clinical trial, neurocognitive deficits can be assessed in the overwhelming majority of patients, and the severity of impairment is similar to meta-analytic estimates. Multiple analyses suggested that a broad cognitive deficit characterizes this sample. These deficits are modestly related to negative symptoms and essentially independent of positive symptom severity.

An interview-based measure of cognition that included informant reports was related to cognitive performance as well as real-world functioning. Interview-based measures of cognition, such as the SCoRS, may be valid coprimary measures for clinical trials assessing cognitive change and may also aid clinicians desiring to assess patients' level of cognitive impairment.

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The Brief Assessment of Cognition in Schizophrenia (BACS) assesses five different domains of cognitive function with six tests, and takes about 30-35 minutes to complete in patients with schizophrenia. Previous work has demonstrated the reliability of this measure, and its sensitivity to the deficits of schizophrenia. However, the relationship of this brief cognitive measure to functional outcome has not been determined. Further, future registration trials for potentially cognitive enhancing compounds may not only assess efficacy with cognitive performance measures, but with assessments of real-world functional outcome and functional capacity. The purpose of this study was to determine the relationship between the BACS and a potential co-primary measure for treatment studies of cognition in schizophrenia, and to determine if such a measure accounts for significant variance in functioning beyond that provided by cognitive function. The current study assessed 60 patients with schizophrenia over the course of six months. Cognitive functions were measured with the BACS. Functional capacity was measured with the UCSD Performance-based Skills Assessment (UPSA). Real-world functional outcome was measured with the Independent Living Skills Inventory (ILSI). BACS composite scores were significantly correlated with functional capacity as measured by the UPSA (r = .65, df = 55, p < .001), and real-world functional outcome as assessed by the ILSI (r = .37, df = 56, p = .005). In multiple regression analyses, UPSA scores did not account for additional variance in real-world functioning beyond that accounted for by the BACS. These data suggest that brief cognitive assessments such as the BACS are able to assess aspects of cognition that are related to important functional measures in clinical trials of cognitive enhancement. They also suggest that the measures being considered as potential co-primary indicators of cognitive function for registration trials are significantly correlated with cognition as assessed by brief cognitive assessments.