The Clock Drawing Test: Performance differences between the free-drawn and incomplete-copy versions in patients with MCI and dementia.

Bárbara Costa Beber,Márcia Lorena Fagundes Chaves,Renata Kochhann,Bruna Matias

doi:10.1590/s1980-5764-2016dn1003009

Abstract

ABSTRACTBackground: The Clock Drawing Test (CDT) is a brief cognitive screening tool for dementia. Several different presentation formats and scoring methods for the CDT are available in the literature. Objective: In this study we aimed to compare performance on the free-drawn and "incomplete-copy" versions of the CDT using the same short scoring method in Mild Cognitive Impairment (MCI) and dementia patients, and healthy elderly participants. Methods: 90 participants (controlled for age, sex and education) subdivided into control group (n=20), MCI group (n=30) and dementia group (n=40) (Alzheimer's disease - AD=20; Vascular Dementia - VD=20) were recruited for this study. The participants performed the two CDT versions at different times and a blinded neuropsychologist scored the CDTs using the same scoring system. Results: The scores on the free-drawn version were significantly lower than the incomplete-copy version for all groups. The dementia group had significantly lower scores on the incomplete-copy version of the CDT than the control group. MCI patients did not differ significantly from the dementia or control groups. Performance on the free-drawn copy differed significantly among all groups. Conclusion: The free-drawn CDT version is more cognitively demanding and sensitive for detecting mild/early cognitive impairment. Further evaluation of the diagnostic value (accuracy) of the free-drawn CDT in Brazilian MCI patients is needed.

Highlights

The Clock Drawing Test (CDT) has been recommended as a brief screening tool for Alzheimer’s disease dementia (AD), with its clinical importance extensively described in the literature.[1,2,3,4] Several different formats of presentation and scoring methods for the CDT are available.[5,6]Different formats of presentation are the free-drawn, the pre-drawn, and the copy methods
The CLOX comprises two parts: CLOX1, an unprompted task that is sensitive to executive control; CLOX2, a copied version that is less dependent on executive skills and more dependent on praxis
The authors hypothesized that the difference between CLOX1 and CLOX2 scores indicated the specific contribution of executive control versus visuospatial praxis to overall performance assessed by the CLOX1.9,10 not discussed in the original CLOX study, the CLOX1, as for any free-drawn task, encompasses visual memory function[3,5] which is not canceled by subtracting it from CLOX2

Summary

Introduction

The Clock Drawing Test (CDT) has been recommended as a brief screening tool for Alzheimer’s disease dementia (AD), with its clinical importance extensively described in the literature.[1,2,3,4] Several different formats of presentation and scoring methods for the CDT are available.[5,6]. Different formats of presentation are the free-drawn, the pre-drawn, and the copy methods. Objective: In this study we aimed to compare performance on the free-drawn and “incomplete-copy” versions of the CDT using the same short scoring method in Mild Cognitive Impairment (MCI) and dementia patients, and healthy elderly participants. The dementia group had significantly lower scores on the incomplete-copy version of the CDT than the control group. Performance on the free-drawn copy differed significantly among all groups.

Objectives

Methods

Results

Conclusion