What is the intersecting pentagons task on the Mini-Mental State Examination (MMSE) assessing in an elderly patient with suspected cognitive impairment?

What the Intersecting Pentagons Task Assesses on the MMSE

The intersecting pentagons task on the MMSE primarily assesses visuospatial ability and visuoconstructive function, with additional evaluation of executive functions including planning and organization. 1

Primary Cognitive Domains Evaluated

The pentagon copying task specifically measures:

• Visuospatial cognition: The ability to perceive and mentally manipulate spatial relationships between objects 1
• Visuoconstructive abilities: The capacity to organize and execute the motor planning required to reproduce a complex geometric figure 2
• Executive functions: Including planning, organization, and the ability to conceptualize the task requirements 1

Clinical Significance and Diagnostic Utility

The pentagon task has particular diagnostic value in differentiating dementia subtypes, especially dementia with Lewy bodies (DLB) from Alzheimer's disease (AD). 3, 2

Specific Performance Patterns:

• Inability to correctly determine the number of angles in the pentagon copy shows 91% specificity for prodromal DLB versus AD, though sensitivity is only 41% 3
• Patients with DLB demonstrate significantly worse performance on this visuoconstructive task compared to those with AD, particularly in early disease stages 3, 2
• The qualitative scoring method (QSPT) evaluates multiple parameters: number of angles, distance/intersection, closure/opening, rotation, and closing-in phenomena 2

Important Clinical Caveats

Population-Specific Limitations:

The intersecting pentagon task presents substantial challenges in illiterate populations and requires careful interpretation based on demographic factors. 4

• Illiterate individuals, females, older adults, and rural/tribal populations face the greatest difficulty completing this task correctly 4
• Educational level, cultural background, and prior exposure to geometric concepts significantly influence performance 4
• The scoring method may need modification when used in largely illiterate populations 4

Test Reliability Issues:

• The pentagon copy task demonstrates poor test-retest reliability in healthy older adults 5
• Inappropriate intrusion of the pentagon drawing into other visuospatial recall tests occurs in approximately 17% of participants, suggesting contamination effects 5
• The task exhibits ceiling effects in cognitively intact individuals, limiting its sensitivity for detecting subtle impairments 5

Practical Assessment Approach

When interpreting pentagon copying performance:

• Document specific errors: Note whether the patient correctly identifies the number of angles (5 per pentagon), maintains proper intersection, achieves closure without gaps, avoids rotation, and prevents closing-in phenomena 2
• Consider demographic context: Adjust expectations based on education level, cultural background, and prior exposure to geometric tasks 4
• Integrate with other findings: Poor pentagon performance combined with subtle extrapyramidal signs and REM sleep behavior disorder symptoms suggests early DLB rather than AD 3
• Use qualitative scoring: The QSPT provides more nuanced assessment than simple pass/fail scoring and may better differentiate dementia subtypes 2

When Pentagon Performance Is Most Informative

The pentagon task provides greatest diagnostic value when:

• Differentiating between DLB and AD in patients with mild cognitive impairment, where poor performance (especially incorrect angle counting) strongly suggests DLB 3
• Tracking visuoconstructive decline over time, as DLB patients show more rapid deterioration on this task compared to AD patients 2
• Identifying visual-constructional apraxia as a prominent early feature suggesting non-AD dementia 2