Clock Drawing Test: A Simple Scoring System for the Accurate Screening of Cognitive Impairment in Patients with Mild Cognitive Impairment and Dementia

Background/Aim: The Clock Drawing Test (CDT) is a valid alternative screening tool to the Mini-Mental State Examination (MMSE) and, crucially, it may be completed faster. The aim of our study was to standardize and simplify the CDT scoring system for screening in three common conditions: mild cognitive impairment (MCI), Alzheimer's disease (AD) and mixed dementia (MD). Methods: We included 188 subjects (43 healthy volunteers, 49 patients with MCI, 54 patients with AD, and 42 patients with MD), who performed the MMSE and CDT. The CDT was evaluated using a modified 4-point scoring system. Results: The healthy subjects had the highest median values for the MMSE and CDT, followed by patients with MCI, AD and MD. The optimal cut-off for all patients and each patient group separately was 3 out of 4 points. Sensitivity was 89% for AD, 93% for MD and 83% for all patients, while specificity was 91%. The MMSE produced similar results. In comparison to the MMSE, sensitivity for MCI was significantly higher using the CDT (20 vs. 69%, respectively). Conclusion: A simple, 4-point scoring system may be used as a screening method for fast and accurate detection of cognitive impairment in patients with MCI, AD and MD. (C) 2018 S. Karger AG, Basel