Clinical Neuroscience Lab
Department of Psychology at Seoul National University
Development of Neuropsychological Tests
Developing neuropsychological tools especially for elderly Koreans has been a major research objective of our lab since its inception. When we published the Korean-Dementia Rating Scale (Chey, 1998), it was the first dementia test to be developed in Korea. From the normative study of the K-DRS (Chey & Lee, 1997), it became clear that neuropsychological tools that accommodated the characteristics of elderly Koreans were necessary. This was followed by the development of the Elderly Memory disorder Scale (EMS; Chey, 2007), which allowed detailed assessment of episodic memory processes in verbal and nonverbal domains in elderly Koreans especially for those with limited education. EMS was developed as a clinical and research tool, and administrating separate subtests was recommended unlike the K-DRS. It has been found that Story Recall Test is sensitive in detecting mild cognitive impairment in elderly Koreans (Baek et al., 2011). Interestingly, errors found in the Clock Drawing Test by illiterate or people with no education were similar to those made by Alzheimer’s dementia, i.e., conceptual errors were observed in both groups (Kim & Chey, 2010). While the conceptual capacity has been deteriorated in the latter, it may never have been developed in the former. These results certify the clinical validity of the K-DRS and EMS developed in consideration of the characteristically large number of low-educated seniors in the Korean population. In 2011, the K-DRS2 was published by further expanding and subdividing age and education norms.
Our lab developed a neuropsychological test to measure reasoning ability that would tap the prefrontal cortex. The Proportional Reasoning Test adapted from a child experimental task (Jeong, Levine, & Huttenlocher, 2007), produced fronto-parietal activation in the fMRI study (Chey, Song, Suk, & Kim, 2013), and was found valid in individuals with limited education, including illiterates.
Considering the close relationship between education and cognitive aging, we conducted a multidisciplinary research (“Brain Fusion”) to reveal the causes of high dementia incidence in Korea, which are not yet clearly identified. The study specifically sought to explore differences in brain volume or connectivity according to the level of cognitive reserve, and found that lower and higher education groups represent different correlation patterns between gray matter volume and memory function (Kwak & Chey, 2017). The differences in brain volume between the two groups were not significant, suggesting that strategies for handling memory tasks, not brain volume itself, are important, and this can be modulated by educational experience. Of note, high correlation of medial temporal lobe gray matter volume and memory task scores was observed. The medial temporal lobe is one of the most vulnerable structures in early stages of AD, and the fact that low-educated elderly people depend more on these structures suggest possible mechanisms about why they are more susceptible to early AD pathology. In addition, it was found that groups that did not complete elementary education had a higher correlation between levels of depression and the performance of memory tasks than those who completed elementary education (Jiyoun Lee, Heyeon Park, & Jeanyung Chey, 2018). Depression is often accompanied by a temporary decrease in cognitive ability such as concentration and memory, and there are numerous reports about an increased risk of dementia in older groups who are suffering from depressive symptoms. Our study suggests that education can act as a protective factor or reserve in this pathological process.
When the fourth edition of Wechsler Adult Intelligence Scale and Memory Scale were developed in the U.S., we took part in the development of the Korean version (Chey, Kim, Park, Hwang, & Hong, 2012; Hwang, Kim, Park, Chey, & Hong, 2012). Due to the popularity of the Wechsler tests around the world, it would allow cross-cultural studies as well as facilitate international collaboration in the field. However, since traditional WMS series normative data has not specifically considered demographic variables such as sex and education, we investigated the impact of education on K-WMS-IV performances. Understanding a potential effect of such variable would add insights into interpretation and diagnostic decision-making in clinical setting. We found that the K-WMS-IV would overestimate cognitive impairment in subjects with less education, while underestimate cognitive impairment in those with more education, and this education effect on memory performance increased as subjects got older (Shin et al. 2016). Meanwhile, the ‘word’ subtest of the WAIS-IV has been reported as a reliable measure to estimate the subject’s potential or premorbid intelligence. However, because the acquisition of vocabulary heavily depend on formal education, it is possible that this interpretation may not be appropriate for Korean elderly people who did not complete elementary education. Heyeon Park et al. showed that the ‘word’ subtest may not be a proper proxy for cognitive reserve for those who did not complete elementary schooling (Heyeon Park, Jeanyung Chey, Jiyoun Lee, 2017).
Figure: Examples of CDT conceptual errors observed most frequently in illiterate individuals with no education and AD pathology
(Kim & Chey, 2010)
최진영(2007). 노인 기억장애 검사 (Elderly Memory disorder Scale). 학지사.
최진영, 김지혜, 박광배, 황순택, 홍상황(2011). 한국판 웩슬러 성인용 기억 검사 4판 (K-WMS-IV). 대구: 한국심리.
황순택, 김지혜, 박광배, 최진영, 홍상황(2011). 한국판 웩슬러 성인 지능 검사 4판 (K-WAIS-IV). 대구: 한국심리.
Baek, M.J., Kim, H.J., Ryu, H., J., Lee, S.H., Han, S.H., Na, H.R., Chang, Y.H., Chey, J., & Kim, S.Y. (2011). The usefulness of the story recall
test in patients with mild cognitive impairment and Alzheimer’s disease. Aging, Neuropsychology, and Cognition, 18, 2, 214-229.
Chey, J. (1998). Korean-dementia rating scale. Seoul, Korea, Hakjisa.
Chey, J. Y., & Lee, S. A. (1997). Development of the norms for the Korean-Dementia Rating Scale. Korean J Clin Psychol, 16, 423-433.
Chey, J., Song, H., Jungsuh, S., & Kim, M. (2013). The proportional reasoning test: A novel assessment tool for Alzheimer's disease and
frontotemporal dementias. Alzheimer's & Dementia: The Journal of the Alzheimer's Association, 4(9), P396.
Jeong, Y., Levine, S. C., & Huttenlocher, J. (2007). The development of proportional reasoning: Effect of continuous versus discrete
quantities.Journal of Cognition and Development, 8(2), 237-256.
Kim, H., & Chey, J. (2010). Effects of education, literacy, and dementia on the Clock Drawing Test performance. Journal of the International
Neuropsychological Society, 16(06), 1138-1146.
Shin, M., Chey, J., Kim, J. H., Park, K. B., Hwang, S. T., Hong, S. H. (2016). Impact of Education on the Korean Wechsler Memory Scale
IV Performances. Korean Journal of Clinical Psychology, 35, 3, 585-599.