Why is mini-mental state examination performance correlated with estimated premorbid cognitive ability?

Dykiert, D., Der, G. , Starr, J. M. and Deary, I. J. (2016) Why is mini-mental state examination performance correlated with estimated premorbid cognitive ability? Psychological Medicine, 46(12), pp. 2647-2654. (doi: 10.1017/S0033291716001045) (PMID:27377546) (PMCID:PMC4988266)

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Background: Tests requiring the pronunciation of irregular words are used to estimate premorbid cognitive ability in patients with clinical diagnoses, and prior cognitive ability in normal ageing. However, scores on these word-reading tests correlate with scores on the Mini-Mental State Examination (MMSE), a widely-used screening test for possible cognitive pathology. The present study aimed to test whether the word-reading tests’ correlations with MMSE scores in healthy older people are explained by childhood IQ or education. Methods: Wechsler Test of Adult Reading (WTAR), National Adult Reading Test (NART), MMSE scores and information about education were obtained from 1024 70-year-olds, for whom childhood intelligence test scores were available. Results: WTAR and NART were positively correlated with the MMSE (r ≈ .40, p<.001). The shared variance of WTAR and NART with MMSE was significantly attenuated by about 70% after controlling for childhood intelligence test scores. Education explained little additional variance in the association between the reading tests and the MMSE. Conclusions: MMSE, which is often used to index cognitive impairment, is associated with prior cognitive ability. MMSE score is related to scores on WTAR and NART largely due to their shared association with prior ability. Obtained MMSE scores should be interpreted in the context of prior ability (or WTAR/NART score as its proxy).

Item Type:Articles
Glasgow Author(s) Enlighten ID:Der, Mr Geoffrey
Authors: Dykiert, D., Der, G., Starr, J. M., and Deary, I. J.
College/School:College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > MRC/CSO SPHSU
Journal Name:Psychological Medicine
Publisher:Cambridge University Press
ISSN (Online):1469-8978
Published Online:05 July 2016
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Psychological Medicine 46(12):2647-2654
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
727651SPHSU Core Renewal: Measuring and Analysing Socioeconomic Inequalities in Health Research ProgrammeAlastair LeylandMedical Research Council (MRC)MC_UU_12017/13IHW - MRC/CSO SPHU