Development of the subjective cognitive function decline scale for middle-aged Koreans.

Objectives: This study developed the Subjective Cognitive Function Decline Scale for Middle-aged South Koreans (SCFD-K), addressing the need for early detection of potential mild cognitive impairment. This study fills a gap in the existing research, which mainly targeted older demographics or generalized cultural differences.

Method: We conducted focus group interviews (FGIs) among 36 participants and with nine experts to answer basic questions related to cognitive decline, after which we developed a draft scale using the Delphi with another 15 experts. To examine the reliability and validity of the scale, an online survey of 2,000 people was conducted.

Results: An exploratory factor analysis identified four distinct factors, which are language, visuospatial function, personality/emotion, and memory, with a total of 20 items (Cumulative variance ratio = 57.76), and a confirmatory factor analysis validated the four-factor structure with a good model fit (CFI = 0.932, TLI = 0.921, RMSEA = 0.057, and SRMR = 0.042) and acceptable internal consistency (Cronbach's α = 0.735-0.907).

Conclusion: This analysis established the SCFD-K as a reliable and valid tool for assessing cognitive decline among middle-aged South Koreans. The findings have key cultural implications and inform proactive interventions and shaping future healthcare strategies in South Korea.