Could a Combination of the Clock Drawing Test and the Mini-Mental Status Examination Be Used to Screen Dementia in a Neurological Setting? Comments with Data from the NEDICES Survey

The interesting paper recently presented in the Journal of Alzheimer’s Disease [1] suggests, in agreement with one recent report [2], a utilization of the clock drawing test (CDT), in combination with the Mini-Mental Status Examination (MMSE), as a screening method for Alzheimer’s disease (AD) and mild cognitive impairment (MCI) in a neurological setting. This is a relatively new use of the CDT and MMSE, because both tests are traditionally and preferably employed in these disorders in population- and community-based surveys [3]. It is well known that the use of the CDT in dementia screening has limitations, as it has good screening precision only in moderate and severe dementia cases [4] and in populations without illiterates or subjects with low education [5]. As such, a recent systematic review does not recommend CDT for MCI screening [6], and our experience demonstrated these facts. In the second cross-sectional survey of the Neurological Disorders in Central Spain (NEDICES) cohort (an elderly population-based cohort with low level of education) [7], we screened 3,698 participants in the second cross-sectional survey with an adaptation of the Foltein’s MMSE and a functional scale (FAQ of Pfeffer), and nearly 3,000 subjects also completed a brief neurological test battery. This battery included an executive test (Trail Making Test), several fluency and memory tests, and a verbal intelligence test [8]. A CDT was also included. For evaluating the CDT psychometric properties in this survey, a “convenience” sample (randomly selected but with higher representation of the more aged) of the nearly 3,000 CDTs of the participants was analyzed. Three neurologists and one psychologist blindly evaluated 150 CDTs with the Shulman [9] and Cacho [10] scoring systems. The scoring concordance between the four investigators was not as high as the diagnostic accuracy in the dementia diagnoses employed independently of the scoring system. Currently, the old Spanish population has a cultural level similar to other European countries, but the cultural endowment of the 1997 elderly cohort survey had more than 10% illiterates—complete or functional—and more than 40% who were only able to read and write. With the data of this preliminary study, we decided to not analyze the CDT scores of the participants in the cohort and the work was unpublished. With this experience, however, it is not possible to recommend the use of the CDT in a population with low cultural levels, such as that presented in this paper (the majority of the people were only able to read and write) [5]. It is noteworthy that the completion of the CDT is short (nearly three minutes) but that the interpretation requires time (if it is not done with an elemental scoring system) and experts. Although the authors of this paper certainly meet the expert criteria, most physicians do not have adequate experience.

Furthermore, the data in this study does not demonstrate that the use of the combination of the two tests for MCI and AD screening increases the sensitivity and specificity of this screening in a neurological setting, because these two measures do not increase the screening capacity of these two tests in a statistically significant way.

In summary, this study is interesting and well done, but I think that it does not modify the knowledge that the CDT and MMSE are adequate instruments for dementia screening in population-based and community settings. It is not clear that the combination of both tests increases the efficacy of MCI and AD screening in a neurological setting. As the authors recognize, more studies are needed to demonstrate this efficacy.

Félix Bermejo-Pareja, MD, PhD
Head of Neurology Department. University Hospital “12 de Octubre”. Madrid. Spain
Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain

References
[1] Cacho J, Benito-León J, García-García R, Fernández-Calvo B, Vicente-Villardón JL,Mitchell AJ (2010) Does the combination of the MMSE and Clock Drawing Test (Mini-clock) improve the detection of mild Alzheimer's disease and mild cognitive impairment? J Alzheimers Dis 22, 889-96.
[2] Aprahamian I, Martinelli JE, Neri AL, Yassuda MS (2010) The accuracy of the Clock Drawing Test compared to that of standard screening tests for Alzheimer’s disease: results from a study of Brazilian elderly with heterogeneous educational backgrounds. Int Psychogeriatr 22, 64-71
[3] Strauss E, Sherman EMS, Spreen O, eds (2006) A Compendium of Neuropsychological Tests. Third Edit. Oxford University Press. Oxford. 
[4] Nishiwaki1 Y, Breeze E, Smeeth L, Bulpitt CJ, Peters R, Fletcher AE (2004) Validity of the Clock-Drawing Test as a screening tool for cognitive impairment in the elderly. Am J Epidemiol 160,797–807
[5] Ainslie NK  Murden RA (1993) Effect of education on the clock drawing dementia screen in non demented elderly patients J Amer Geriatr Soc 41, 249-252 
[6] Ehreke L, Luppa M,¨KonigHH, Riedel-Heller SG (2010) Is the Clock Drawing Test a screening tool for the diagnosis of mild cognitive impairment? A systematic review. Int Psychogeriatr 22, 56-63.
[7] Morales JM, Bermejo FP, Benito-Leon J, Rivera-Navarro J, Trincado R, Gabriel SR, Vega S; NEDICES Study Group (2004) Methods and demographic findings of the baseline survey of the NEDICES cohort: adoor-to-door survey of neurological disorders in three communities from Central. Spain. Public Health 118, 426-33
[8] Bermejo-Pareja F, Benito-Leon J, Vega S, Medrano MJ, Roman GC; on behalf of the Neurological Disorders in Central Spain (NEDICES) Study Group( 2008)  Incidence and subtypes of dementia in three elderly populations of central Spain. J Neurol Sci 264, 63-72 
[9] Shulman KI (2000) Clock-drawing: Is it the ideal cognitive screening test? Int J Geriatr Psychiatry 15, 548–561 
[10] Cacho J, García-García R, Arcaya J, Vicente JL, Lantada N (1999) A proposal for the application and scoring of the clock drawing test in Alzheimer’s disease (in Spanish). Rev Neurol 28, 648–655.