Epidemiologic Reviews Advance Access originally published online on June 27, 2008
Epidemiologic Reviews 2008 30(1):77-83; doi:10.1093/epirev/mxn007
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ARTICLES |
Population-based Cohort Studies on Premorbid Cognitive Function in Schizophrenia
From the Institute of Psychiatry, King's College London, London, United Kingdom
Correspondence to Dr. James H. MacCabe, P.O. Box 63, Institute of Psychiatry, King's College London, de Crespigny Park, London SE5 8AF, United Kingdom (e-mail: j.maccabe{at}iop.kcl.ac.uk).
accepted for publication April 29, 2008.
Many previous studies have found associations between poor cognitive function and schizophrenia. However, the majority of these studies used retrospective data, leading to the possibility of selection and recall biases. Retrospective studies are also unable to distinguish whether cognitive deficits exist prior to the onset of schizophrenia, suggesting that they are important in etiology, or following onset, suggesting that they are secondary to the disorder or its treatment. The current review used a systematic search strategy to identify and summarize the results of all studies that have used population-based cohorts to examine associations between prospectively collected data on premorbid cognitive functioning in childhood or adolescence and subsequent risk for schizophrenia. Three broad categories of study have addressed these questions: birth cohort designs with cognitive testing during childhood, army conscript designs with cognitive performance measured at conscription, and studies using school grades. Birth cohort and conscript studies are consistent in reporting strong associations between poor performance on cognitive batteries and increased risk of schizophrenia. Studies on school performance have been less consistent, although the largest such study showed strong associations across all school subjects. In conclusion, children and adolescents with poor cognitive abilities in childhood are at increased risk of schizophrenia. This suggests that poor cognitive function is either directly causal or associated with causal factors that are involved in etiology.
adolescent development • child development • cohort studies • intelligence • learning disorders • review • schizophrenia
IQ, intelligence quotient