Neuropsychological predictors of transition from healthy cognitive aging to mild cognitive impairment: The PATH through life study

Objective: To identify neuropsychological predictors of transition from healthy cognitive aging to mild cognitive impairment (MCI) or any mild cognitive disorder (any-MCD) in a community-based longitudinal study of aging. Design: Longitudinal Participants: Two thousand eighty-two individuals, aged 60-64 years and participating in a prospective epidemiologic study of mental health, and aging were assessed at two time points 4 years apart for MCI using the International Consensus Criteria, the clinical dementia rating scale (CDR, 0.5), or any of a suite of criteria sets for MCDs (any-MCD). Measurements: Logistic regression was used to assess the neuropsychological predictors of conversion to diagnosis including the Mini-Mental State Examination, immediate and delayed recall (IR and DR), Digit Backward, Spot-the-Word (STW), Symbol Digits Modalities Test (SDMT), simple and choice reaction time, and reaction time variability. Results: Of the 2,082 Participants with no cognitive impairment in the first wave of data collection, 18 Participants were diagnosed with MCI, 32 with CDR 0.5, and 64 Participants presented with any-MCD 4 years later. The main neuropsychological predictors of conversion identified in multivariate analyses were measures of IR/DR, STW, Symbol Digit Modalities Task, and reaction time variability. Conclusions: Although most measures were significant predictors of conversion to MCI or any-MCD when assessed independently, four tests (IR/DR, STW, SDMT, and simple reaction time variability) accounted for the explained variance in diagnosis when all tests were assessed together. When predictive value, stability across clinical categories, and psychometric characteristics were considered together, the reaction time variability measure was the best predictor of future cognitive disorder.