Short-term practice effects and variability in cognitive testing in a healthy elderly population.
Krenk, Lene a,b,c,*; Rasmussen, Lars S. b; Siersma, Volkert D. d; Kehlet, Henrik a,c
[Article] Experimental Gerontology. 47(6):432-436, June 2012.

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Background: Cognitive decline in the elderly is a subject of intense focus. However, there is a lack of consensus regarding definition of significant decline in connection with repeated testing and the interpretation of cognitive tests results must take into account the practice effect and variability in test performance.

The aim of this study was to collect cognitive test results with repeated testing in an elderly healthy population.

Methods: 161 healthy controls >= 60 years were included. Cognitive testing was performed upon entry into the study, at 1 week and 3 months. Practice effect was evaluated on 7 neuropsychological measures and reference values of clinically important changes were calculated according to z-scores above 1.96.

Results: Test scores improved significantly (p < 0.05) in 2 of 7 measures between baseline and 2nd test and in 6 of 7 measures between baseline and 3rd test session. No significant correlation was found between magnitude of practice effect and age or educational status.

Conclusion: Practice effect and variability in cognitive testing in the elderly are important to consider when evaluating changes in cognitive performance over a short period of time.

(C) 2012Elsevier, Inc.