A Comprehensive Evaluation of the Process of Copying a Complex Figure in Early- and Late-Onset Alzheimer Disease: A Quantitative Analysis of Digital Pen Data

Abstract

Background The Rey-Osterrieth Complex Figure Test (RCFT) is a neuropsychological test that is widely used to assess visual memory and visuoconstructional deficits in patients with cognitive impairment, including Alzheimer disease (AD). Patients with AD have an increased tendency for exhibiting extraordinary behaviors in the RCFT for selecting the drawing area, organizing the figure, and deciding the order of images, among other activities. However, the conventional scoring system based on pen and paper has a limited ability to reflect these detailed behaviors. Objective This study aims to establish a scoring system that addresses not only the spatial arrangement of the finished drawing but also the drawing process of patients with AD by using digital pen data. Methods A digital pen and tablet were used to copy complex figures. The stroke patterns and kinetics of normal controls (NCs) and patients with early-onset AD (EOAD) and late-onset AD (LOAD) were analyzed by comparing the pen tip trajectory, spatial arrangement, and similarity of the finished drawings. Results Patients with AD copied the figure in a more fragmented way with a longer pause than NCs (EOAD: P=.045; LOAD: P=.01). Patients with AD showed an increased tendency to draw the figures closer toward the target image in comparison with the NCs (EOAD: P=.005; LOAD: P=.01) Patients with AD showed the lower accuracy than NCs (EOAD: P=.004; LOAD: P=.002). Patients with EOAD and LOAD showed similar but slightly different drawing behaviors, especially in space use and in the initial stage of drawing. Conclusions The digitalized complex figure test evaluated copying performance quantitatively and further elucidated the patients’ ongoing process during copying. We believe that this novel approach can be used as a digital biomarker of AD. In addition, the repeatability of the test will delineate the process of executive functions and constructional organization abilities with disease progression.

Overview of the Complex Figure Test and Its Clinical Application in Neuropsychiatric Disorders, Including Copying and Recall

“…It could distinguish them well ( 24 ). To also extract the parameters stably and accurately in digital and automated CFT assessment tool development ( 25 ), developed a simplified ROCF ( Figure 1L ). The figure has few strokes and is not easy to overlap in a small space.…”

“…However, the traditional scoring methods based on pen and paper have limitations for detecting these abnormal behaviors. Therefore, it is necessary to establish a scoring method for a digital device to increase the scoring of the drawing process ( 25 ).…”

“…It realized the semi-automatic analysis of Bennett-Levy scoring and found that the symmetry score can be a good marker for non-verbal executive function. To finely analyze drawing behavior patterns and establish a simple and objective digital scoring method, Kim et al ( 25 ) used a tablet (Samsung Galaxy Book 12) to record the drawing process and automatically extract stroke parameters (time, speed, and length) and graphical space information (position of center and mass). It also uses 2D technology to analyze the shape similarity between the original and copied figures.…”

“…The results found that AD patients copied the figure in a more fragmented way with a longer pause and were more inclined to move the figure closer to the target image with lower accuracy than normal control. Late-onset AD showed signs of leftward deviation when drawing the figure ( 25 ). The digital Complex Figure Test can quantitatively evaluate drawing performance and further clarify organizational strategies.…”

Comparison of RCF Scoring System to Clinical Decision for the Rey Complex Figure Using Machine-Learning Algorithm

“…The RCF scoring system for participants can be performed in 2 ways: the standard RCF scoring system and clinical decision based on clinical dementia rating (CDR). 8 9 The CDR is evaluated using the Korean Screening Questionnaire (KDSQ) on a scale of 0–3 ( Table 1 ). 10 11 The KDSQ is a dementia screening questionnaire that identifies early dementia patients.…”