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PREDICTION OF CEREBRAL AMYLOID POSITIVITY BASED ON NEUROPSYCHOLOGICAL TEST PERFORMANCE IN NON-DEMENTED ELDERLY INDIVIDUALS

      Background

      Cerebral beta amyloid protein (Aβ) deposition is the core pathological hallmark of Alzheimer’s disease (AD). Although amyloid PET imaging can be used to identify Aβ deposition human brains in vivo, it is still very expensive and cannot easily be available in many clinical settings. We aimed to find out neuropsychological tests or their combinations that could predict Aβ deposition status in non-demented elderly individuals.

      Methods

      One hundred and eighty-two non-demented (149 cognitively normal and 33 amnestic mild cognitive impairment) elderly individuals (mean age 69.7 years, range 55-87) who participated in the Korean Brain Aging Study for Early Diagnosis & Prediction of Alzheimer’s disease (KBASE), an ongoing prospective cohort study, were included. All subjects underwent comprehensive neuropsychological assessment and 11C-labelled Pittsburgh Compound B positron emission tomography (PiB-PET). PiB-PET Images were classified as amyloid-positive if the mean 11C-PiB retention value was over 1.21 in at least one of the four regions, which included the following: the frontal, lateral temporal, lateral parietal, precuneus/posterior cingulate cortices.

      Results

      The Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) word list recall/recognition, the Rey Complex Figure Test (RCFT) 3-/30-minute delays, the Wechsler Memory Scale-IV (WMS-IV) logical memory (LM) immediate/delay/recognition, and the Wechsler Adult Intelligence Scale (WAIS-IV) block design (BD) test, which had significant mean differences between amyloid-positive and amyloid-negative groups, were initially selected. Thereafter, possible combinations of the tests were tested through a series of logistic regression analyses in order to determine the final composite test score with the highest prediction accuracy. The composite score calculated by the summation of WMS-IV LM delayed recall and WAIS-IV BD scores were finally selected. The prediction accuracy of the score for amyloid positivity was 72.5% in overall non-demented group and 78.5% in only cognitively normal subgroup.

      Conclusions

      Our result suggests that the composite score calculated by summing the scores of WMS-IV LM delayed recall and WAIS-IV BD is useful for prediction of amyloid positivity in clinical practice for non-demented elderly.