A longitudinal study of neurocognitive function in individuals at-risk for psychosis

Keefe, Richard S.E.; Perkins, Diana O.; Gu, Hongbin; Zipursky, Robert B.; Christensen, Bruce K.; Lieberman, Jeffery A.

doi:10.1016/j.schres.2006.06.041

« Previous Next »Schizophrenia Research
Volume 88, Issue 1 , Pages 26-35, December 2006

A longitudinal study of neurocognitive function in individuals at-risk for psychosis

Richard S.E. Keefe
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
- Corresponding author. Box 3270, Duke University Medical Center, Durham, NC 27710, USA. Tel.: +1 919 684 4306; fax: +1 919 684 2632.
Diana O. Perkins
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
Hongbin Gu
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
Robert B. Zipursky
- Department of Psychiatry, University of Toronto School of Medicine, Toronto, ON, Canada
Bruce K. Christensen
- Department of Psychiatry, University of Toronto School of Medicine, Toronto, ON, Canada
Jeffery A. Lieberman
- Department of Psychiatry, Columbia University School of Medicine, New York, NY, USA

Received 15 March 2006; received in revised form 27 June 2006; accepted 28 June 2006. published online 23 August 2006.

Abstract

Introduction

Clinically defined prodromal diagnostic criteria identify at-risk individuals with a 35–40% likelihood of developing a psychotic disorder within a year. The time course and predictive value of cognitive deficits in the development of psychosis has not been established.

Methods

A comprehensive neurocognitive battery and clinical assessments were administered to 37 subjects meeting Criteria of Prodromal States (COPS) criteria for being at risk for psychosis, and two comparison groups: 59 first episode and 47 healthy subjects. Subjects were also evaluated at 6-month and 1-year follow-up periods. Primary analyses used a neurocognitive composite score derived from individual neurocognitive measures, including measures of vigilance, verbal memory, working memory, and processing speed.

Results

At-risk subjects performed more poorly than healthy subjects (t=2.93, P=0.01), but better than first episode subjects (t=4.72, p<0.0001). At-risk subjects were particularly impaired on measures of vigilance and processing speed. Cognitive composite scores were significantly lower in at-risk subjects who progressed to psychosis (N=11; z=−1.2), while those at-risk subjects who did not progress to psychosis (N=17) performed better (z=−0.5), and not significantly different from controls. Poor CPT performance combined with better WAIS-R digit symbol performance predicted progression to psychosis. Severity of neurocognitive deficits was not related to duration of prodrome or to time to development of psychosis and neurocognitive function improved in all subjects except those who progressed to psychosis.

Conclusion

Neurocognitive impairment emerges early in the course of psychotic illness. Performance on tests of neurocognition may prove to be an early risk predictor for subsequent development of psychotic disorders.

Keywords: Neurocognition, Prodrome, Psychosis, Schizophrenia, First episode, Development