Development of a cognitive composite for preclinical Alzheimer’s disease (CPAD) in Korean older adults

Abstract

AbstractBackgroundAs tracking subtle cognitive declines in the preclinical stage of Alzheimer’s disease (AD) is difficult with traditional individual outcome measures, need for cognitive composite for preclinical AD is widely recognized. We aimed to develop culturally appropriate cognitive composite that sensitively identifies subtle cognitive decline of preclinical AD in Korean older adults.MethodA total 225 cognitively normal elderly individuals, who completed baseline and 2‐year follow‐up evaluation including clinical assessments and comprehensive neuropsychological tests and baseline amyloid positron emission tomography (PET) in the Korean Brain Aging Study for the Early Diagnosis and Prediction of Alzheimer’s Disease (KBASE), were included. Tests of episodic memory, orientation, and executive function were carefully selected through review of previously established composite scores. Three candidate composites including Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) word list recall (WLR), logical memory (LM) II, and Mini‐mental status examination (MMSE) in common, and letter fluency test, category fluency test, or Stroop color and word test, were selected.ResultStudent t‐tests demonstrated that only the composite composed of WLR, LM II, MMSE, and LF (Composite 1) showed a significant difference in score decline over two‐year follow‐up period between Aβ positive and negative group (P = 0.03). Linear mixed model analyses also showed that the Aβ x time interaction effect was significant only for Composite 1 (P = 0.026). In contrast, we did not find any significant results for other two candidate composites (Composite 2 and 3). Based on the results, Composite 1 was chosen as the final CPAD.ConclusionCPAD can be used to assess subtle cognitive decline of preclinical AD in clinical research settings, especially in clinical trials with Korean older adults with preclinical AD. It also may be used for monitoring progression or treatment benefits in clinical practices.