The value of clock drawing in identifying executive cognitive dysfunction in people with a normal Mini-Mental State Examination score.

BACKGROUND

Executive cognitive dysfunction can precede the memory disturbances of dementia. People with executive cognitive dysfunction can have a normal Mini-Mental State Examination (MMSE) score but still have severe functional limitations. We evaluated the usefulness of clock drawing in identifying people with executive dysfunction who have a normal MMSE score.

METHODS

We reviewed the charts of consecutive patients referred between July 1999 and June 2000 to a multidisciplinary geriatric assessment clinic because of concerns about functional inabilities. The patients had all undergone the Executive Interview for the diagnosis of executive cognitive dysfunction as well as an MMSE and clock-drawing test (scored by 2 methods: one described by Watson and colleagues [the Watson method] and one described by Sunderland and colleagues [the Sunderland method]).

RESULTS

We reviewed the charts of 68 patients (40 women, 28 men); their mean age was 79 years (range 55-94). Thirty-six patients had an MMSE score of less than 24, and 32 had a "normal" MMSE score (24-30). Among those with a normal MMSE score, 22 had an abnormal Executive Interview score. Using the Executive Interview as the gold standard, the sensitivity and specificity of the Watson method of scoring clock drawings to predict an abnormal Executive Interview score were 59% and 70% respectively; the corresponding values were 18% and 100% for the Sunderland method.

INTERPRETATION: The presence of an abnormal MMSE score alerts clinicians to the possibility of cognitive impairment. For patients referred for geriatric assessment who have a normal MMSE score, a clock-drawing test, scored by either the Watson or the Sunderland method, is a moderately sensitive and specific adjunct for detecting executive cognitive dysfunction.