Mental Status Examination


The best examination methods for dementia are

  • Clock drawing test
    – Positive LR of 5 (post test probability +30%)
    – Does not depend on patient’s educational status
  • MMSE
    – <20 has a positive LR of 15 (very likely)
    – >26 has a positive LR of 0.1 (very unlikely)
    – Between needs further testing

Clock drawing test


Normal if the most of the 12 numbers are in order (clockwise arrangement)
Abnormal if counter-clockwise arrangement, unusual/incorrect arrangement, irrelevant figures


  • Affected by patient’s educational status


Confusion assessment method has positive LR of 10 (+45%) and negative LR of 0.2 (-30%)

Mnemonic = 4As

  • Acute onset
  • Attention impaired (tested by minus 7 from back)
  • Answers inappropriate OR
  • Altered consciousness

Reference: Evidence-based physical diagnosis, Steven McGee. – 2nd ed


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