Digital-like contamination in the Clock Drawing Test: Norms across six scoring systems
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Published on: November 23, 2019
Ciro Rosario Ilardi1, François Osiurak2, Nadia Gamboz1
1Department of Education, Psychology and Communication, Suor Orsola Benincasa University, Naples, Italy.
Background:
In an era in which time is increasingly read from digital devices, the Clock Drawing Test (CDT) may capture not only cognitive impairment but also construct-irrelevant variance associated with reduced analog clock usage.
Objective:
We aimed to derive updated normative data for CDT while modeling the impact of digital-like (DL) contamination on score interpretation.
Methods:
This cross-sectional study enrolled cognitively healthy adults aged 18-94 years. Clock drawings were scored using six established methods. DL patterns were identified, including five-minute sequencing (e.g., 5-55) and post-meridiem mapping (e.g., 13-23). We then examined whether the frequency of digital timekeeping was associated with CDT performance and the probability of relying on DL strategies. Psychometric rules for score adjustment and interpretation were computed.
Results:
The sample included 560 participants (357 women). The scoring methods showed moderate-to-strong intercorrelations (ρ = 0.45-0.79), with good-to-excellent inter-rater reliability (ICC = 0.78-0.95). DL patterns occurred in 45 individuals (8%) and were not associated with cognitive functioning. As participants' age increased, the more frequent the use of digital devices for time-checking, the poorer the CDT performance (b = -0.051, 95% CI [-0.086, -0.017]) and the greater the likelihood of producing DL patterns (b = 0.052, 95% CI [0.017, 0.087], OR = 1.053, 95% CI [1.017, 1.091]). Both age and DL contamination emerged as consistent predictors of CDT performance.
Conclusions:
The clinical validity of CDT may be deteriorating. This study provides updated norms with optional DL adjustments. Their effectiveness in decreasing misclassifications requires diagnostic studies involving clinical samples.
