Journal of the International Neuropsychological Society



Normal rates of cognitive change in successful aging: The Freedom House Study


DONALD R.  ROYALL  a1 a2 a3 c1 , RAYMOND  PALMER  a4 , LAURA K.  CHIODO  a2 and MARSHA J.  POLK  a2
a1 Department of Psychiatry, University of Texas Health Science Center, San Antonio, Texas
a2 Department of Medicine, University of Texas Health Science Center, San Antonio, Texas and the South Texas Veterans' Health System Audie L. Murphy Division, Geriatric Research Education and Clinical Center (GRECC)
a3 Department of Pharmacology, University of Texas Health Science Center, San Antonio, Texas
a4 Department of Family and Community Medicine, University of Texas Health Science Center, San Antonio, Texas

Article author query
royall dr   [PubMed][Google Scholar] 
palmer r   [PubMed][Google Scholar] 
chiodo lk   [PubMed][Google Scholar] 
polk mj   [PubMed][Google Scholar] 

Abstract

We determined the rates of cognitive change associated with twenty individual measures. Participants included 547 noninstitutionalized septuagenarians and octogenarian residents of a comprehensive care retirement community who were studied over three years. Latent growth curves (LGC) of multiple cognitive measures were compared to a LGC model of the rates of change in Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL). All curves were standardized relative to each variable's baseline distribution. Baseline scores were within their expected normal age-specific ranges. Most measures showed significant rates of change over time. There was also significant variability about those rates, suggesting clinical heterogeneity. Many deteriorated over time, as did ADLs and IADLs. However, performance on some measures improved, consistent with learning effects. The rates of change in two measures, the Executive Interview and the Trail Making Test, were closely related to decline in IADLs. These results suggest that age-related cognitive decline is a dynamic longitudinal process affecting multiple cognitive domains. Heterogeneity in the rates of cognitive change may reflect the summed effects of age and comorbid conditions affecting cognition. Some measures may be ill-suited for measuring age-related changes in cognition, either because they are insensitive to change, or hindered by learning effects. Nonverbal measures appear to be particularly well suited for the prediction of age-related functional decline. These observations are relevant to the definition and diagnosis of “dementing” conditions. (JINS, 2005, 11, 899–909.)

(Received April 21 2005)
(Revised August 29 2005)
(Accepted August 30 2005)


Key Words: Aging; Assessment; Disability; Dementia; Longitudinal; Executive function.

Correspondence:
c1 Reprint requests to: Dr. Donald Royall, Department of Psychiatry, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78284-7792. E-mail: royall@uthscsa.edu