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Clock drawing test in very mild Alzheimer's disease
C Esteban-Santillan1, R Praditsuwan, H Ueda
1University Alzheimer Center, University Hospitals of Cleveland, Ohio 44120, USA.
Journal of the American Geriatrics Society
|October 20, 1998
Summary
The clock drawing test can help detect early Alzheimer's disease (AD). Errors in drawing clock hands, especially two or more, strongly suggest dementia, while normal hand placement may indicate its absence in older adults.
Area of Science:
- Neurology
- Geriatrics
- Cognitive Science
Background:
- Early detection of Alzheimer's disease (AD) is crucial for timely intervention.
- The clock drawing test (CDT) is a widely used screening tool for cognitive impairment.
- Identifying specific CDT elements for early AD detection remains an area of research.
Purpose of the Study:
- To evaluate the efficacy of the CDT in predicting very mild Alzheimer's disease (AD).
- To identify key clock drawing features that distinguish individuals with mild AD from cognitively healthy older adults.
Main Methods:
- Retrospective analysis of clock drawings from 41 patients with mild AD and 39 age/education-matched controls.
- Blind scoring of drawings using the Clock Drawing Interpretation Scale and the Rouleau et al. system.
- Calculation of predictive values for various scoring cut-offs.
Main Results:
- Two or more errors in clock hand depiction yielded 100% positive predictive value for AD.
- A score of 2 or less on the Rouleau et al. hand-placement component showed 94% positive predictive value for AD.
- Normal clock hand placement had a negative predictive value of 62% for AD.
Conclusions:
- Two or more clock hand drawing errors warrant further dementia investigation.
- While normal hand placement does not rule out AD, it suggests it is unlikely in community-dwelling older adults.
- The CDT, particularly hand placement, is a valuable tool for screening very mild Alzheimer's disease.