How do you interpret a clock face drawing in a cognitive assessment?

How to Interpret a Clock Face Drawing in Cognitive Assessment

The clock drawing test is scored dichotomously (0 or 2 points) in the Mini-Cog, where any abnormality receives 0 points, while a completely correct clock (all numbers present in correct positions with hands showing the requested time) receives 2 points. 1

Standardized Scoring Approach

Mini-Cog Dichotomous Scoring (Primary Care Setting)

• Award 2 points if the clock is completely normal: all numbers 1-12 are present in correct sequence and position, and hands correctly display "10 past 11" (or the requested time) 1
• Award 0 points for any deviation from perfect performance, including:
  • Missing or incorrectly placed numbers 1
  • Incorrect hand placement 1
  • Conceptual errors in clock design 1
  • Perseveration or stimulus-bound responses 1

Integration with Total Mini-Cog Score

• Combine the clock score (0 or 2) with word recall (0-3 points) for a total possible score of 5 1
• A total score <3 indicates concern for possible dementia and warrants further evaluation with multidomain testing, neurologic examination, laboratory studies, and imaging 1

Alternative Scoring Systems for Specialty Settings

MoCA Clock Scoring (0-3 Points)

• 3 points maximum: Contour (1 point), numbers (1 point), and hands (1 point) 1
• Important caveat: MoCA clock criteria have demonstrated low interrater reliability (ICC = 0.12-0.31) and require repeated training for consistent scoring 2
• Consider adding a clock copy condition (takes <1 minute) to improve diagnostic accuracy and reveal expected dementia subgroup patterns 2

Detailed Quantitative Systems

• Rouleau 10-point system provides subscale scores for clock face representation, layout of numbers, and position of hands, with age and education adjustments required 3
• Shulman system demonstrates 82% sensitivity and 75.7% specificity for dementia detection 4
• Sunderland system shows 72.6% sensitivity but 87.9% specificity 4

Qualitative Error Analysis

Key Error Patterns to Identify

• Conceptual errors: Misunderstanding what a clock represents or its purpose 1
• Visuospatial deficits: Numbers crowded in one area, poor spatial distribution 1
• Executive dysfunction: Poor planning, perseveration, inability to complete the task 1, 5
• Graphomotor impairment: Tremor, poor line quality (distinguish from cognitive impairment) 1

Clinical Significance

• Clock drawing can detect executive cognitive dysfunction even when MMSE scores are normal (24-30), with Watson scoring method showing 59% sensitivity and 70% specificity for executive dysfunction 5
• The test assesses visuospatial cognition, conceptualization, and executive function (planning/organization) simultaneously 1

Critical Clinical Pitfalls

Never Use Clock Drawing in Isolation

• Always combine with memory testing and functional assessment 1
• An abnormal clock draw alone does not establish dementia diagnosis 1
• Consider alternative causes: motor disabilities, visual impairment, low education, cultural factors 1

When Clock Drawing Cannot Be Performed

• Use the Memory Impairment Screen (MIS) as an alternative for patients with motor disabilities preventing clock completion 1
• The Picture-Based Memory Impairment Screen overcomes educational and cultural limitations 1

Mandatory Follow-Up for Abnormal Results

• Proceed to multidomain mental status testing (MoCA, STMS, or ACE-III) 1
• Complete neurologic examination 1
• Order appropriate laboratory studies and brain imaging 1
• Screen for depression (PHQ-2/PHQ-9) and delirium (Confusion Assessment Method), as these conditions can mimic dementia 1

Practical Administration Tips

Standardized Instructions

• Provide a preprinted large circle 1
• Instruct: "Fill in the numbers of a clock face and set the hands to show 10 past 11" 1
• Repeat directions if needed, but do not provide additional guidance 1

Timing Considerations

• Clock drawing takes 1-2 minutes to complete 1
• The entire Mini-Cog (including 3-word registration, clock draw, and recall) requires only 2-4 minutes 1