Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 54, Issue 12 B549-B566, Copyright © 1999 by The Gerontological Society of America
Behavioral biomarkers of aging: illustration of a multivariate approach for detecting age-related behavioral changes
AL Markowska and SJ Breckler
Department of Psychology, Johns Hopkins University, Baltimore, MD 21218, USA. [email protected]
The goal of the current project is to develop a multivariate statistical
strategy for the formation of behavioral indices of performance and,
further, to apply this strategy to establish the relationship between age
and important characteristics of performance. The strategy was to begin
with a large set of measures that span a broad range of behaviors. The
behavioral effects of the following variables were examined: Age (4, 12,
24, and 30 months), genotype [Fischer 344 and a hybrid (F1) of Fischer 344
and Brown Norway (F344xBN)], gender (Fischer 344 males and Fischer 344
females), long- term diet (ad lib diet or dietary restriction beginning at
4 months of age), and short-term diet (ad lib diet or dietary restriction
during testing). The behavioral measures were grouped into conceptually
related indicators. The indicators within a set were submitted to a
principal component analysis to help identify the summary indices of
performance, which were formed with the assumption that these component
scores would offer more reliable and valid measures of relevant aspects of
behavioral performance than would individual measures taken alone. In
summary, this approach has made a number of important contributions. It has
provided sensitive and selective measures of performance that indicated
contributions of all variables: psychological process, age, genotype,
gender, long-term and short-term diet and has increased the sensitivity of
behavioral measures to age-related behavioral impairment. It has also
improved task-manageability by decreasing the number of meaningful
variables without losing important information, consequently providing a
simplification of the pattern of changes.
