Early cognitive impairment: Role of clock drawing test

Abstract

Background: Folstein's Mini Mental Status Examination (MMSE) often fails to identify executive dysfunction even if quite severe. Detailed neuropsychological tests and extensive bedside tests are available to evaluate executive function, but most of them are time consuming. This study was done to determine the value of a Clock Drawing Test (CDT) as a simple tool to identify cognitive dysfunction in various neurological disorders and to assess its utility as an adjunct to MMSE in identifying executive dysfunction in a a busy out patient department (OPD). Methods: A total of 81 patients suffering from neurological disorders and 81 controls were studied. All subjects received the MMSE and the CDT. The CDT is divided into an unprompted task that is sensitive to executive control (CDT 1) and a copying task which is not (CDT 2). Result: All the three tests (CDT 1, CDT 2 and MMSE) could recognize cognitive and executive function deficits, when compared with age and sex matched controls (p<0. 001). CDT scores correlated strongly with the level of executive function deficits. CDT+MMSE detected 95% cases as abnormal as compared to 47% detected by MMSE alone. Conclusion: CDT along with MMSE can detect executive control deficits and cognitive deficits. The CDT 1 tests executive control performance, while CDT 2 tests posterior cortical deficits.