Three Times of the Clock Drawing Test Rated with BaJa Scoring in Patients with Early Alzheimer's Disease
Abstract
Aim: The Clock Drawing Test (CDT) is a popular screening test to detect of dementia. The aim of the present research was to determine the role of the test in diagnosing early stages of Alzheimer's disease (AD).
Patients and methods: The Mini-Mental State Examination (MMSE) and the CDT with three times 11:10, 23:20 and 5:40 were examined in 77 cognitively normal seniors (NOS) and in 77 patients diagnosed with early AD according to NIA-AA criteria. All CDTs were scored according to the instructions in the Addenbrooke's and Montreal cognitive tests (ACE, MoCA), Shulman's system and by our newly developed BaJa system with five dichotomous questions and 0-5 scale.
Results: MMSE and CDT scores with any of the three times (11:10, 23:20, 5:40) assessed by any system were significantly lower for the early AD patients than for the NOS group (p < 0.01). The 23:20 was significantly more difficult than 11:10 for all participants (p = 0.003).
A comparison of patients and NOS for three times of the CDT showed a cut-off score for BaJa LESS-THAN OR EQUAL TO 4 points, sensitivity 54-65%, specificity of 59-75% and the area under the receiver operating curve (AUC) around 0.7. The MMSE cut-off score LESS-THAN OR EQUAL TO 27 points was associated with higher sensitivity of 86%, specificity 96% and AUC 0.96.
There were no differences between the four CDT scoring systems with respect to AUCs. Conclusion: Although the CDT with 23:20 is more difficult than the other times, the CDT in general is not useful for early detection of AD due to its low sensitivity and specificity, regardless of what time or scoring system is used.