Longitudinal Changes in Clock Drawing Test (CDT) Performance before and after Cognitive Decline

Abstract

BackgroundMany scoring systems exist for clock drawing task variants. However, none of them are reliable in evaluating longitudinal changes of cognitive function. The purpose of this study is to create a simple yet optimal scoring procedure to evaluate cognitive decline using a clinic-based sample.MethodsClock-drawings from 121 participants (76 individuals with no dementia and later did not develop dementia after a mean 41.2-month follow-up, 45 individuals with no dementia became demented after a mean 42.3-month follow-up) were analyzed using t-test to determine a new and simplified CDT scoring system. The new scoring method was then compared with other commonly used systems.ResultsIn the converters, there were only 7 items that are significantly different between the initial visits and the second visits. We propose a new scoring system that includes the seven critical items: numbers are equally spaced (12–3–6–9) (p = 0.031), the other eight numbers are marked (p = 0.022), numbers are clockwise (p = 0.002), all numbers are correct (p = 0.030), distance between numbers is constant (p = 0.016), clock has two hands (p = 0.000), arrows are drawn (p = 0.003). Compared with other traditionally used scoring methods, this based change clock drawing test (BCCDT) has one of the most balanced sensitivities/specificities with a clinic-based sample.ConclusionsThe new CDT scoring system provides further evidence in support of a simple and reliable clock-drawing scoring system in follow-up studies to evaluate cognitive decline, which can be used in assessing the efficacy of medicine.

Drawing Disorders in Alzheimer’s Disease and Other Forms of Dementia

“…The scoring systems share commonalities, but each may reflect different cognitive components and be correlated with different areas of brain atrophy [58]. However, independently from the scoring procedure, performance on CDT in demented patients seems to be inversely correlated with lesion load in medial temporal lobe, in subcortical structures and in periventricular white matter [59,60] and might provide prognostic information for cognitive decline [61,62]. Some authors suggested that qualitative analysis of errors in clock drawing might improve diagnostic accuracy for dementia screening.…”

“…Poor performance on CDT might predict future development of AD in patients with MCI [98], but not all qualitative scoring procedures might be sufficiently sensitive to capture longitudinal changes of CDT from MCI to AD [61]. A recent metaanalysis [99] confirmed that the CDT might reveal a useful measure of cognitive decline over time, and that conceptual clock drawing errors (with particular mention of hand and number placement) would be most informative about the cognitive decline.…”

Combined effect of obstructive sleep apnea and chronic smoking on cognitive impairment

“…The steps of how patients drew the clocks were recorded by the examiner. The results were analyzed according to the 30-point system [22,23]: the first step of CDT is to anchor the "12-3-6-9" on the clock, which is referred to as "30-point system-A (Anchoring) part" (CDT-A, a total of 4 points), and the rest 26 points consist of 13 items to reflect the drawing results, which was called "30-point system-C (Clockface) part" (CDT-C, a total of 26 points). The CDT-A is closely correlated with memory function, while the CDT-C reflects visuospatial and executive function [22].…”

Executive dysfunction assessed by Clock‐Drawing Test in older non‐demented subjects with metabolic syndrome is not mediated by white matter lesions

“…Authors have indicated that deficits in executive functions may be detected earlier than those in memory tasks, irrespective of whether subjects report cognitive complaints. Executive functions are the ability to plan, judge, reason, solve problems and organize; and attention, abstraction and mental flexibility play pivotal roles in executive control . Impairment in executive function predicts Alzheimer's disease and vascular dementia …”

“…Executive functions are the ability to plan, judge, reason, solve problems and organize; and attention, abstraction and mental flexibility play pivotal roles in executive control . Impairment in executive function predicts Alzheimer's disease and vascular dementia …”