The influence of education on performance of adults on the Clock Drawing Test

Abstract

The Clock Drawing Test (CDT) is an important instrument for screening individuals suspected of having cognitive impairment. Objective: To determine the influence of education on the performance of healthy adults on the CDT. Methods: A total of 121 drawings by healthy adults without neurological complaints or impairments were analysed. Participants were stratified by educational level into 4 subgroups: 27 illiterate adults, 34 individuals with 1-4 years of formal education, 30 with 5-11 years, and 30 adults with >11 years' formal education. Scores on the CDT were analyzed based on a scale of 1-10 points according to the criteria of Sunderland et al. (1989).¹ The Kruskal-Wallis test was applied to compare the different education groups. Tukey's multiple comparisons test was used when a significant factor was found. Results: Although scores were higher with greater education, statistically significant differences on the CDT were found only between the illiterate and other educated groups. Conclusion: The CDT proved especially difficult for illiterate individuals, who had lower scores. These results suggest that this screening test is suitable for assessing mainly visuoconstructional praxis and providing an overall impression of cognitive function among individuals, independently of years of education.

Formal language assessment in low-educated healthy subjects

“…These studies have tended to find greater homogeneity in cognitive behavior among individuals with 8 or more years of education. 1 , 3 , 4 , 13 The same effect can be observed on language tests, although tasks that are highly dependent on the lexical buffer, such as oral and written naming and verbal fluency tests, appear to differ. 2 , 12 …”

“…Although many studies demonstrate the influence of education on cognitive development, 1 - 4 , 8 , 9 , 12 , 13 the impact of low education on the various cognitive functions appears to differ. In a previous study assessing several cognitive domains of individuals with 0-22 years of formal education, the authors noted that the education effect was non-linear: significant differences were evident between groups with 0-3 versus 10-22 years of formal education, whereas the same was not observed between groups with 4-9 and 10-22 years of formal education.…”

“…A number of studies investigating different cognitive functions reveal statistically significant disparities between groups with different levels of education on linguistic tasks such as oral comprehension, reading, graphical comprehension, naming, lexical availability, dictation and written naming of actions, 2 , 8 , 12 as well as on language tasks involving semantic knowledge, judgement of traits and naming, besides tasks of calculus, 3 memory 1 and orofacial praxis. 15 Depending on the tasks or tests employed, some studies have found differences only between illiterate subjects and educated individuals, irrespective of level of education, 13 whereas others have reported disparities across all 3 or some educational levels. 16 With regard to language, given the complexity and number of different language tasks needed to assess this ability, performance on different language tasks according to education are highly disparate.…”

Can a combination of two neuropsychological tests screen for mild neurocognitive disorder better than each test alone? A cross-sectional study

“…It was also noted that the combination of VF and BNT has better sensitivity and specificity in the educated group, while that was better with VF/CDT in the illiterate group. In a study by de Noronha et al to determine the influence of education on the performance of healthy adults on the CDT found that CDT was not strongly influenced by education in its application, except for illiterate individuals, who attained statistically significant lower scores [14]. Accordingly, it can be used clinically for screening cognitive deficits irrespective of education.…”

Influence of age and schooling in written discourse of healthy adults

“…The education level is highly recognized as a factor that impacts in tasks that are used to assess not only the language, but also other cognitive functions, such as memory, attention, executive function, and even nonverbal cognitive tasks (Ardila, et al, 2010;Noronha, Barreto, & Ortiz, 2018). The discursive production is regarded as a complex task that requires the integration of several linguistic cognitive skills, such as memory, idea selection, organization, planning, and naming (Alexander, 2006;Rogalski et al, 2010;Andreetta, Cantagallo, & Marini, 2012;Wills, Capilouto, & Wright, 2012;Cannizzaro & Coelho, 2013).…”