Clock Drawing Test: Types of Errors and Accuracy in Early Cognitive Screening.

Area of Science:

• Neurology
• Geriatrics
• Cognitive Science

Background:

• The Clock Drawing Test (CDT) is a widely used screening tool for cognitive disorders.
• Its ease of use is contrasted by poor predictive value in mild cognitive impairment cases.

Purpose of the Study:

• To evaluate the Clock Drawing Test (CDT) for screening early-stage cognitive impairment.
• Focus on biomarker-verified Alzheimer's disease (AD) and depressive disorder (DD).

Main Methods:

• Analysis of CDT performance in 172 AD patients, 70 DD patients, and 58 healthy adults.
• CDT scoring utilized both semi-quantitative (Shulman) and itemized (Mendez) criteria.
• Logistic regression analyzed predictive variables based on Mini-Mental State Examination (MMSE) scores.

Main Results:

• Uneven number spacing was a significant predictor for both DD and AD patients with high MMSE scores.
• As MMSE scores declined (24-26), errors in setting clock hands became predictive.
• CDT demonstrated acceptable discrimination for AD and DD in low MMSE conditions (AUCs ranging from 0.739 to 0.827).
• Itemized scoring showed acceptable discrimination in high MMSE conditions, while Shulman scoring performed poorly for both AD and DD.

Conclusions:

• The CDT has limited utility for screening very mild cognitive deficits, particularly when cognitive performance is only slightly below the healthy range.
• Modern diagnostics should ideally precede significant cognitive decline for effective intervention.
• Itemized CDT scoring may offer superior discrimination in early-stage cognitive impairment compared to Shulman scoring.