Télécharger le texte intégral - ISPED-Enseignement à distance

AnnexesAmerican Journal of Epidemiology Advance Access published November 14, 2006192American Journal of EpidemiologyCopyright ª 2006 by the Johns Hopkins Bloomberg School of Public HealthAll rights reserved; printed in U.S.A.DOI: 10.1093/aje/kwk017Practice of EpidemiologySensitivity of Four Psychometric Tests to Measure Cognitive Changes in BrainAging-Population–based StudiesCécile Proust-Lima 1,2 ,Hélène Amieva 2,3 , Jean-Francxois Dartigues 2,3 , and Hélène Jacqmin-Gadda 1,21 INSERM E0338, Bordeaux, France.2 Université Victor Segalen Bordeaux 2, Bordeaux, France.3 INSERM U593, Bordeaux, France.Received for publication April 11, 2006; accepted for publication July 5, 2006.Choosing the measure of cognition in an epidemiologic study investigating cognitive changes over time isa challenging question. A powerful measure must be able to detect small cognitive changes in all the range ofcognition observed in the target population. This work aims at comparing the sensitivity to detect cognitive changesin the observed range of cognition of four widely used psychometric tests in an aging-population–based studythrough a nonlinear latent process model, assuming that the psychometric tests are nonlinear noisy transformationsof their common factor. With data from the French prospective cohort study PAQUID (1989–2001), the authorsfound that the Mini-Mental State Examination and the Benton Visual Retention Test exhibited a better sensitivity tocognitive changes in low levels of cognition, while the Digit Symbol Substitution Test was more sensitive tochanges in high levels of cognition. In contrast, the Isaacs Set Test shortened at 15 seconds appeared to besensitive to small changes in all the range of cognition and, thus, represents an appropriate measure of cognition inpopulation-based studies including both highly normal and severely impaired subjects.aging; cognition; dementia; epidemiologic methods; neuropsychological testsAbbreviations: BVRT, Benton Visual Retention Test; DSST, Digit Symbol Substitution Test; IQR, interquartile range;IST15, Isaacs Set Test shortened at 15 seconds; MMSE, Mini-Mental State Examination.With the increasing number of people suffering fromneurodegenerative diseases, especially Alzheimer’s disease,investigating cognitive changes over time has receivedgrowing attention in population-based cohort studies for understandingthe natural history of the neurodegenerative diseasesand in intervention trials designed to assess the effectsof drugs on neuropsychological functioning (1, 2). In thesestudies, cognition is generally assessed through a battery ofpsychometric tests repeatedly administered to the subjects.Collecting several cognitive tests may be useful, because thisallows exploration of the various cognitive domains (memoryfunctioning, attention, or executive functions) and becausethe tests often have different metrologic properties. Inparticular, some tests are very sensitive to small changes athigh levels of cognition, while others are more sensitive tochanges at the lower levels. As a consequence, when studyingthe effects of drugs or the aging process on cognition,results may differ considerably according to the properties ofthe test being used (3). A way to deal with this problem is tostudy the change over time of the common latent cognitivelevel underlying the battery of cognitive tests used (4).However, administering an extensive battery of neuropsychologicaltests can turn out to be difficult, because of theduration (and thus cost) of the evaluation and also becausesubjects presenting cognitive impairment are more prone torefuse long testing sessions than cognitively intact elderlysubjects (5). In this way, it would be of substantial interestto compare the properties of commonly used cognitive testsCorrespondence to Cécile Proust-Lima, INSERM E0338, Institut de Santé Publique, d’Epidémiologie et de Développement, Université deBordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France (e-mail: cecile.proust@isped.u-bordeaux2.fr).1