Biomedical subjects

Daniel Zimprich

Publications and source records attributed to Daniel Zimprich.

3 recordsLinked to original sources

PubMed2002

Can longitudinal changes in processing speed explain longitudinal age changes in fluid intelligence?

The processing-speed theory of cognitive aging contends tha age-related declines in intellectual function reflect the consequences of age-related slowing of processing speed. Cross-sectional data support this assumption. The association between 4-year changes in processing speed and 4-year changes in fluid intelligence was examined with a sample of 417 older adults. Changes in processing speed correlated .53 with changes in fluid intelligence. The difference in the explanatory power of processing speed regarding age-related differences and age-related changes is discussed with reference to other longitudinal studies and methodological considerations.

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PubMedDate not supplied

Cross-sectionally and longitudinally balanced effects of processing speed on intellectual abilities.

The processing speed theory of cognitive aging states that declines in intellectual abilities other than processing speed are mainly due to a slowing of processing speed. Cross-sectional studies have provided support for the processing speed theory as for age-related cognitive differences. Longitudinal studies, in turn, have provided weaker support for the processing speed theory as for cognitive age changes. The present study aims to reconcile this discrepancy of cross-sectional and longitudinal results by constructing a "fair" test of the processing speed theory, i.e., a test that balances the cross-sectional age range and the time period covered longitudinally. Data from 83 older adults came from the Bonn Longitudinal Study on Aging. Using hierarchical linear models, it is shown that, although cross-sectional age differences and longitudinal changes in the intellectual abilities were equal, processing speed only attenuated cross-sectional age effects in cognition but virtually did not reduce longitudinal change effects in cognition. This persisting difference in the explanatory power of processing speed regarding age-related differences and age-related changes is discussed with reference to other longitudinal studies and statistical issues regarding cross-sectional and longitudinal studies of aging.

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PubMedDate not supplied

Are changes in cognitive functioning in older adults related to changes in subjective complaints?

In many areas of intellectual functioning, age-related declines in older adults' performance and increases in subjective complaints about intellectual performance are observed. However, the literature mostly reports very low relations between functioning and respective complaints. This finding could be the consequence of examining the relation between subjective complaints and the perceived level of functioning. If, however, persons are sensitive to relative changes in performance, they might base their subjective judgment on changes in the level of cognitive functioning. With 202 subjects (mean age=63 years) and two measurements, the authors examine (a) the relation between functioning and complaints at each measurement point, and (b) the relation between changes in functioning and changes in complaints between the measurement points with latent difference variables. The results indicate that there is no relation between level of functioning and level of complaints, but that there is a substantial relation between changes in functioning and complaints.

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