The neuropsychological test scores of 2,030 cognitively normal older adults were examined to evaluate performance patterns as they related to time of day (TOD) at which testing was initiated. Multiple regression analyses were used to examine the association of TOD with scores on seven neuropsychological tests used in the clinical evaluation of dementia. Episodic memory performance was significantly related to TOD, while memory span and verbal fluency were not. Best performance occurred during early morning hours and late afternoon; worst performance occurred mid-day (i.e., noon). These findings may have implications for clinical assessment, the design of research on dementia, and the daily functioning of older adults.
Bibliographical noteFunding Information:
The authors wish to thank Suzanne Craft, Ph.D. and Patricia Boyle, Ph.D. for their many helpful and insightful comments about this manuscript. This work was supported by a cooperative agreement from the National Institute on Aging to the University of Washington, Seattle, Washington (U01AG15477). NIA collaborators participated in the design and conduct of the study. Naproxen sodium and matching placebo were supplied by Bayer Healthcare, and celecoxib and matching placebo were supplied by Pfizer, Inc. Dr Brandt receives royalties on sales of the Hopkins Verbal Learning Test–Revised.
- Circadian rhythms
- Episodic memory
- Performance variability