Clock drawing is sensitive to executive control: a comparison of six methods

Area of Science:

• Neuroscience
• Cognitive Psychology
• Gerontology

Background:

• Clock-drawing tasks (CDTs) are widely used to assess cognitive function.
• Executive Control Function (ECF) is crucial for daily activities and is often impaired in Alzheimer's disease (AD).
• Existing CDT scoring systems vary in their ability to capture ECF deficits.

Purpose of the Study:

• To compare the efficacy of six different CDT scoring systems in differentiating probable AD cases from controls.
• To determine which CDT scoring system best correlates with established measures of ECF (EXIT25) and general cognitive function (MMSE).
• To identify the specific cognitive resources engaged by clock drawing.

Main Methods:

• Six CDT scoring systems were evaluated.
• Participants included 33 probable AD cases and 52 independent living controls.
• Correlational analyses and multivariate regression models were used to assess relationships between CDT scores, EXIT25, MMSE, age, and education.

Main Results:

• All CDT scoring systems significantly differentiated AD cases from controls.
• All CDTs showed significant correlations with the EXIT25, with associations largely maintained after controlling for age, education, and MMSE.
• The CLOX: An Executive Clock-Drawing Task scoring system demonstrated the strongest association with both EXIT25 (R2 = .68) and MMSE (R2 = .72) scores.
• CLOX explained incrementally more variance in ECF compared to other CDT scoring systems.

Conclusions:

• Clock drawing engages both executive and general cognitive resources.
• The CLOX scoring system is a sensitive and specific measure for assessing ECF deficits in probable AD.
• CLOX offers superior predictive value for ECF compared to other commonly used CDT scoring systems.