Elucidating the contributions of processing speed, executive ability, and frontal lobe volume to normal age-related differences in fluid intelligence.

Full Abstract

One theory of normal cognitive aging asserts that decreases in simple processing speed mediate the age-related decline of fluid intelligence. Another possibility is that age-related atrophic changes in frontal brain structures undermine the functioning of executive abilities, thereby producing the same decline. In this study, we used principal components analysis to derive a measure of fluid-spatial intelligence in 197 normal adults between 20 and 92 years of age. Measures of perceptual comparison speed, working memory, and executive ability, as well as regional brain volumes based on high resolution magnetic resonance imaging were obtained from a subsample of 112 participants. We then conducted a series of hierarchical multiple regression analyses to test whether (1) the processing speed theory, (2) frontal-executive theory, or (3) some combination of these best accounted for age-related variation in fluid intelligence. The results showed that perceptual comparison speed, executive ability, and frontal lobe volume each made significant contributions to a regression equation that explained 57% of the variance in fluid intelligence. These findings suggest that both the processing speed and frontal-executive theory of cognitive aging are partially correct and complement one another.

Author information

Author/s: Schretlen, D (D); Pearlson, G D (GD); Anthony, J C (JC); Aylward, E H (EH); Augustine, A M (AM); Davis, A (A); Barta, P (P);

Affiliation: Department of Psychiatry and Behavioral Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA. dschret(-atsign-)jhmi.edu

Grants: R01 AG 11859 (Agency:NIA NIH HHS)

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, U.S. Gov't, P.H.S.

Journal: Journal of the International Neuropsychological Society : JINS (J Int Neuropsychol Soc), published in ENGLAND. (Language: eng)

Reference: 2000-Jan; vol 6 (issue 1) : pp 52-61

Dates: Created 2000/05/03; Completed 2000/05/03; Revised 2007/11/14;

PMID: 10761367, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

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