WASHINGTON A new look at tests of mental aging reveals a good news-bad news situation. The bad news is all mental abilities appear to decline with age, to varying degrees. The good news is the drops are not as steep as some research showed, according to a study published by the American Psychological Association.
"There is now convincing evidence that even vocabulary knowledge and what's called crystallized intelligence decline at older ages," said study author Timothy Salthouse, PhD.
Longitudinal test scores look good in part because repeat test-takers grow familiar with tests or testing strategies, said the University of Virginia psychologist. Factoring out these "practice effects" showed a truer picture of actual mental aging, according to Salthouse.
Still, the declines, although pervasive, are smaller than thought, according to the report in the July issue of Neuropsychology. That finding contradicts data gathered by the other major research approach to aging, cross-sectional studies, which compare the performance of different age groups at the same time.
With both methods subject to bias, "It remains important to recognize the limitations of each type of study design when interpreting results," Salthouse said.
To learn what really happens as people age, Salthouse tackled how different research methods have led to different findings. Cross-sectional studies that compared the abilities of younger and older adults showed big drops in key areas. Longitudinal studies suggested that, until about age 60, abilities are stable or even improve. Which type of study, if either, was right?
To find out, Salthouse analyzed data on five key cognitive abilities from the longitudinal Virginia Cognitive Aging Project. Scores were available for 1,616 adults age 18 to more than 80 on tests of reasoning, spatial visualization, episodic memory, perceptual speed and vocabulary. The data were collected over an aver
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American Psychological Association