Intraindividual variability in neurocognitive speed: a comparison of Parkinson's disease and normal older adults.

Full Abstract

We examined whether intraindividual variability of neurocognitive speed, or inconsistency, is greater in stages of Parkinson's disease (PD) as compared to a matched group of normal older adults. Intraindividual variability was assessed using four reaction time (RT) (simple and complex) tasks. We examined three sets of correlates:
executive functioning (Stroop (interference index), Trail Making Test (Part B), and Digit Ordering Test), finger tapping speed, and gait speed. The participants were matched on age, sex, and education, and did not differ in global cognitive functioning. There were 50 patients with a clinical diagnosis of idiopathic PD (29 men and 21 women) who ranged from 65 to 84 years (M=71.5, S.D.=4.7) and 48 matched healthy older adults who ranged from 65 to 84 years (M=71.5, S.D.=4.9). Multiple analyses of variance showed that the PD patients were slower on all three complex RT tasks, and more inconsistent than healthy older adults on the most complex (eight-choice) RT task. Individuals with advanced disease had slower neurocognitive speed and more inconsistency than patients with earlier stage PD. Poorer executive functioning was associated with slower neurocognitive performance in healthy older adults, mild PD patients, and especially severe PD patients. Greater inconsistency in speed was related to poorer executive functioning in late stage PD (for the most complex task) and in healthy older adults (for the simplest task), indicating that motor and cognitive domains have functional coupling (i.e., as one becomes compromised so does the other). Intraindividual variability was not correlated with tapping speed and gait speed in any group. Executive functioning and neurocognitive speed may be valid and distinct clinical markers of disease progression in PD.

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Author information

Author/s: de Frias, Cindy M (CM); Dixon, Roger A (RA); Fisher, Nancy (N); Camicioli, Richard (R);

Affiliation: Division of Neurology, University of Alberta, Edmonton, Alberta, Canada. defrias(-atsign-)ualberta.ca

Grants: R37 AG08235 (Agency:NIA NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: Neuropsychologia (Neuropsychologia), published in England. (Language: eng)

Reference: 2007-Jun; vol 45 (issue 11) : pp 2499-507

Dates: Created 2007/05/29; Completed 2007/10/16; Revised 2007/12/03;

PMID: 17507058, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Aged
Aged, 80 and over
Aging - physiology; psychology
Analysis of Variance
Case-Control Studies
Choice Behavior - physiology
Cognition - physiology
Female
Humans

Humans
Male
Matched-Pair Analysis
Parkinson Disease - physiopathology; psychology
Psychomotor Performance - physiology
Reaction Time - physiology
Reference Values
Reproducibility of Results
Severity of Illness Index

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