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Abstract:
Abstract: No consensus exists as to which components of
working memory are relatively spared with aging and which are most
affected. Studies have indicated that processing speed, executive
functions, and storage capacity decline with age. It is unclear,
however, which factor(s) are most responsible for age-related
cognitive decline. In order to examine the components affected by
aging, we compared the performance of 60 younger (YNS, mean age
20.2; mean education 14.7) and 82 older (ONS, mean age 69.4; mean
education 15.2) normal subjects on tests of storage (3 tests),
working memory (3 tests), reaction time (3 tests), and executive
functions (3 tests). ONS performed significantly worse than YNS on
every test (p<.0001). These effects remained significant
(p<.05) when vocabulary and education were covaried. Logistic
regression analyses determined the subset of cognitive measures on
which YNS and ONS differed, simultaneously adjusting each measure
for the others. A significant model (p<.0001) showed that YNS
and ONS were differentiated by three variables: Vocabulary, Stroop
Interference, and Go/No-Go Reaction Time. These results suggest
that aging negatively affects inhibitory ability and processing
speed and that other cognitive impairments related to aging stem
from the deterioration in these capacities. Both inhibition and
processing speed must be considered when examining the effect of
aging on cognitive functions; controlling for only one factor may
be insufficient.
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