Using Multivariate Base Rates of Low Scores to Understand Early Cognitive Declines on the Uniform Data Set 3.0 Neuropsychological Battery

Objective: Low neuropsychological test scores are commonly observed even in cognitively healthy older adults. For batteries designed to assess for and track cognitive decline in older adults. documenting the multivariate base rates (MBRs) of low scores is important to differentiate expected from abnormal low score patterns. Additionally, it is important for our understanding of mild cognitive impairment and preclinical declines to and determine how such score patterns predict future clinical states. Method: The current study utilized Uniform Data Set Neuropsychological Battery 3.0 (UDS3NB) data for 5,870 English-speaking, older adult participants from the National Alzheimer's Coordinating Center from 39 Alzheimer's disease Research Centers from March 2015 to December 2018. MBRs of low scores were identified for 2,608 cognitively healthy participants that had completed all cognitive measures. The association of abnormal MBR patterns with subsequent conversion to mild cognitive impairment and dementia were explored. Results: Depending on the operationalization of "low" score, the MBR of demographically adjusted scores ranged from 1.40 to 79.2%. Posttest probabilities using MBR methods to predict dementia status at 2-year follow up ranged from .06 to .33, while posttest probabilities for conversion to mild cognitive impairment (MCI) ranged from .12-.32. Conclusions: The data confirm that abnormal cognitive test scores are common among cognitively normal older adults. Using MBR criteria may improve our understanding of MCI. They may also be used to enrich clinical trial selection processes through recruitment of at-risk individuals.