Validity of the Tablet-Based Digital Cognitive Test (SCST) in Identifying Different Degrees of Cognitive Impairment

Background: As society ages, the incidence of Alzheimer's disease and other dementias has surged, highlighting the importance of early dementia diagnosis. The Seoul Cognitive Status Test (SCST), a digital neuropsychological test, is designed for the early detection of cognitive impairment and has been standardized to establish reliability and validity. This study aims to verify whether the SCST effectively discriminates between groups based on three cognitive statuses (subjective cognitive decline [SCD], mild cognitive impairment [MCI], Dementia) in a large sample. We also seek to determine whether the SCST discriminates between individuals with three different cognitive statuses as defined by the Cognitive Dementia Rating (CDR).

Methods: We enrolled 254 participants from a dementia clinic who underwent a comprehensive neuropsychological battery (Seoul Neuropsychological Screening Battery-II) during the dementia evaluation by experienced neurologists (55 with SCD, 126 with MCI, 73 with dementia). In addition, the degree of cognitive decline in participants was classified by CDR level (186 with CDR 0.5, 52 with CDR 1, 15 with CDR 2). One-way analysis of variance was used to compare SCST scores according to each of the three cognitive status groups and CDR levels.

Results: The SCST total score, cognitive domain scores (attention, language, visuospatial function, memory, executive function), and most of the subtest scores decreased significantly in the order of SCD, MCI and dementia. Likewise, the differences in SCST scores between CDR levels were significant, particularly in distinguishing between CDR 0.5 and CDR 1.

Conclusion: This study reaffirmed that the SCST can significantly discriminate between groups of individuals with SCD, MCI, and dementia based on a large sample. Furthermore, differences in SCT scores were found across the levels of CDR, confirming the clinical utility of the SCST. These findings suggest that the SCST is an efficient and useful neuropsychological test for the sensitive detection of early cognitive impairment.