Intersecting Pentagons Testing on Mental Status Examination
The intersecting pentagons test is a visuospatial/constructional task included in the Mini-Mental State Examination (MMSE) that assesses the patient's ability to copy two overlapping five-sided figures, primarily evaluating visuospatial function and executive abilities as part of cognitive screening for dementia. 1
What the Test Measures
The intersecting pentagons component of the MMSE specifically evaluates:
- Visuospatial and constructional abilities through the patient's capacity to accurately reproduce the geometric figures 1
- Executive function including planning and spatial organization required to create the overlapping configuration 2
- Praxis (the ability to perform learned motor tasks) as part of the broader cognitive assessment 1
Scoring and Administration
Standard MMSE Scoring
- Binary scoring (0 or 1 point) is used in the traditional MMSE, where the patient receives 1 point only if the drawing is acceptable according to original MMSE instructions 3
- Acceptable criteria require: two five-sided figures, proper intersection creating a four-sided figure in the overlap, and reasonable approximation of the pentagon shapes 2
Enhanced Scoring Methods
- Qualitative scoring systems (such as the QSPT or Bourke scale) provide more nuanced assessment by evaluating specific parameters including number of angles, distance/intersection quality, closure/opening of figures, rotation, and closing-in phenomena 4, 3
- These detailed scoring methods demonstrate superior discriminative ability compared to binary scoring, with sensitivity of 85.5% and specificity of 66.9% for detecting Alzheimer's disease when using the Bourke scale 3
Clinical Significance and Diagnostic Value
Differential Diagnosis Between Dementia Types
- Failure on pentagon copying strongly suggests dementia with Lewy bodies (DLB) over Alzheimer's disease (AD) with 88% sensitivity and 59% specificity in patients with MMSE scores ≥13 2
- DLB patients show significantly greater impairment on this task compared to AD patients at similar stages of dementia, reflecting the more prominent visuospatial deficits characteristic of DLB 2, 4
- Progressive decline patterns differ between dementia types, with DLB showing steeper deterioration in pentagon copying performance over time 4
Limitations in Screening
The binary pentagon scoring on the MMSE does not effectively discriminate AD from healthy controls (p = 0.839), making it insufficient as a standalone screening tool 3. However, when analyzed with qualitative scoring systems, the test becomes clinically useful 3.
Important Caveats and Pitfalls
Educational and Cultural Factors
- Illiterate populations face substantial difficulty with the intersecting pentagons task, with illiterate participants, females, older individuals, and rural/tribal groups showing the greatest challenges 5
- The scoring method requires adjustment when used in largely illiterate populations, as educational level significantly impacts performance 5
- Education level affects interpretation across all cognitive screening tools, though the pentagon test is particularly vulnerable to this bias 5
Comparison to Alternative Tests
- The wire cube from the Montreal Cognitive Assessment (MoCA) demonstrates superior sensitivity (74% versus 26%) for detecting cognitive impairment in Parkinson's disease compared to intersecting pentagons, likely due to greater task complexity 6
- For comprehensive visuospatial assessment, the MoCA's wire cube is preferred over the MMSE pentagons in clinical settings where detecting mild cognitive impairment is the priority 6
Context Within Broader Cognitive Assessment
The MMSE, including the pentagon test, should be used primarily for tracking cognitive change over time in established dementia cases rather than as a primary screening tool 7. For initial cognitive screening:
- The Mini-Cog (2-4 minutes) is preferred with higher sensitivity (76%) and no copyright restrictions 7, 8
- The MoCA has superior sensitivity (90%) for detecting mild cognitive impairment and should be used when more comprehensive assessment is needed 7, 9
- Any cognitive screening score must be interpreted within comprehensive evaluation including medical history, functional assessment, neuropsychiatric evaluation, and laboratory testing—scores alone are not diagnostic 7, 8