[Clock drawing in dementia: its reliability and relation to the neuropsychological measures]

To examine the reliability and validity of clock drawing (CD) for evaluating dementia patients in Japan, we investigated the CD performance and its relation to several neuropsychological tests in 150 demented patients including 105 patients with Alzheimer disease and 30 age- and education-matched non-demented subjects (16 patients with mild cognitive impairment and 14 normals). Patients were also evaluated using the Mini-mental State Exam (MMSE), Wechsler Memory Scale (WMS), Kohs Block Design, and word fluency. CD was scored using the Shulman method. CD scores showed a high interrater reliability (r = 0.97). CD by non-demented subjects was essentially normal. As a screening test for Alzheimer disease (AD, mean MMSE = 18.0), CD had a sensitivity of 57.1% and a specificity of 96.7%. However, four of eight AD patients who showed normal MMSE score (> or = 24) drew abnormal clocks. CD scores in dementia were significantly correlated with performance on the Block Design (r = 0.68), MMSE (r = 0.56), and the Mental Control subtest in the WMS (r = 0.58). Stepwise regression analysis revealed that performance on the MMSE and the Block Design explain 53.8% of the variance in the CD scores. These findings indicate that low CD score by the Shulman method may be reflective of a constructional disability and general severity of dementia. CD is not so sensitive as the result of the original report when the patient group includes milder cases of AD. CD is, however, an efficient screening test for detecting and following the patients with dementia, especially combined with the MMSE.