title: Neurocognitive indicators of clinical high-risk states for psychosis: a critical review of the evidence.
abstract: The present review investigates the empirical evidence from cross-sectional and long-term follow-up studies on neurocognitive indicators of an increased risk for developing schizophrenia spectrum psychoses in clinically defined high-risk samples. First, the investigations at the Cologne center for early recognition and intervention are briefly summarized and then integrated within the available literature. Thirty-two studies with original data could be identified by extensive literature search. Cross-sectional investigations of neurocognitive baseline assessments in high-risk samples with unknown conversion status have produced rather inconsistent results. Nevertheless, most convincing evidence could be collected for abnormal functioning in processing speed measures (digit symbol coding, Trailmaking Test-B, Stroop Color Naming), the Continuous Performance Test, verbal working memory measures, verbal memory and learning, and verbal fluency, though negative findings have also been reported in every instance. Moreover, high-risk subjects were found to perform both at the schizophrenia performance level and at a close to normal level. Longitudinal follow-up assessments provided predictive evidence with regard to psychosis conversion for measures of processing speed and of verbal memory and learning. However, a substantial number of negative findings does not allow for straight-forward conclusions. Finally, some reasons for inconsistent findings are discussed critically speculating on demographic differences, reliability and sample sizes, and conceptual imprecision in communicating results.
authors.affiliation: Department of Psychiatry and Psychotherapy, University of Cologne, Kerpener Str. 62, 50937, Cologne, Germany. ralf.pukrop@uk-koeln.de
authors.forename: Ralf
authors.initials: R
authors.lastname: Pukrop
authors.forename: Joachim
authors.initials: J
authors.lastname: Klosterkötter
mesh_terms: D000818:Animals; D003071:Cognition / Q000502:physiology; D003072:Cognition Disorders / Q000150:complications / Q000175:diagnosis / Q000523:psychology; D003430:Cross-Sectional Studies; D019317:Evidence-Based Medicine / Q000592:standards*; D006801:Humans; D008570:Memory, Short-Term / Q000502:physiology; D009483:Neuropsychological Tests / Q000592:standards; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000209:etiology / Q000523:psychology*; D012307:Risk Factors
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