HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Rabbitt, P. Articles by Wong, D. PubMed PubMed Citation Articles by Rabbitt, P. Articles by Wong, D.

Death, Dropout, and Longitudinal Measurements of Cognitive Change in Old Age

¹ Department of Experimental Psychology, University of Oxford, England and University of W. Australia.
² Department of Statistics, University of Oxford, England.

Address correspondence to P. M. A. Rabbitt, Department of Experimental Psychology, University of Oxford, England. E-mail: Patrick.Rabbitt{at}psy.ox.ac.uk

During a 20-year longitudinal study of cognitive change in old age 2,342 of 5,842 participants died and 3,204 dropped out. To study cognitive change as death approaches, we grouped participants by survival, death, dropout, or dropout followed by death. Linear mixed-effects pattern-mixture models compared rates of cognitive change before death and dropout from four quadrennial administrations of tests of fluid intelligence, vocabulary, and verbal learning. After we took into account the significant effects of age, gender, demographics, and recruitment cohorts, we found that approach to death and dropout caused strikingly similar reductions in mean test scores and amounts of practice gains between successive quadrennial testing sessions. Participants who neither dropped out nor died showed significant but slight cognitive declines. These analyses illustrate how neglect of dropout miscalculates effects of death, of worsening health, and of all other factors affecting rates of cognitive change.

Key Words: Cognitive change • Death • Dropout