Can an 18-point clock-drawing scoring system predict dementia in elderly individuals with mild cognitive impairment?

Abstract

The purpose of this study was to develop a clock-drawing scoring system better suited to detecting possible early markers of dementia in individuals with mild cognitive impairment (MCI). We modified the scoring system of Freedman et al. (1994), in which the major components are integrity of the circle, placement and size of the hands, and placement and sequence of the numbers. We rescored the clock-drawing test using a novel 18-point scoring system, which emphasizes hand elements—number of hands, direction indicated, and size differences. We retrospectively assessed 123 individuals (ages 58–88 years) selected from the Memory Clinic at the Jewish General Hospital in Montreal. These consisted of 21 normal elderly individuals (NORM group), 41 participants with mild cognitive impairment who did not develop dementia on follow-up visits (MCI-NP), 41 participants with mild cognitive impairment who became demented after a 48-month follow-up (MCI-D), and 20 participants diagnosed with Alzheimer's disease (AD). On the 18-point system, the MCI-NP and the MCI-D did not show any difference on overall total score (p = .166), However, using Pearson chi-squares to examine the within-categories effects comparing the mildly cognitively impaired groups (MCI-NP and MCI-D), there were three significant hand items that appear to be possible early markers of progression to dementia. The clock has two hands (p = .043), hour hand is towards correct number (p = .023), and size difference of the hands is respected (p = .004), all showed significant differences between progressors and nonprogressors. The 18-point clock-drawing scoring system may have advantages in better indicating MCI individuals more likely to progress to dementia.