Mild Cognitive Impairment in Late Middle Age in the Wisconsin Registry for Alzheimer's Prevention Study: Prevalence and Characteristics Using Robust and Standard Neuropsychological Normative Data

Clark LR, Koscik RL, Nicholas CR, Okonkwo OC, Engelman CD, Bratzke LC, Hogan KJ, Mueller KD, Bendlin BB, Carlsson CM, Asthana S, Sager MA, Hermann BP, Johnson SC

Archives of Clinical Neuropsychology. 2016; 31(7):675–688.


OBJECTIVE: Detecting cognitive decline in presymptomatic Alzheimer's disease (AD) and early mild cognitive impairment (MCI) is challenging, but important for treatments targeting AD-related neurodegeneration. The current study aimed to investigate the utility and performance of internally developed robust norms and standard norms in identifying cognitive impairment in late middle-age (baseline age range = 36-68; M = 54). METHOD: Robust norms were developed for neuropsychological measures based on longitudinally confirmed cognitively normal (CN) participants (n= 476). Seven hundred and seventy-nine participants enriched for AD risk were classified as psychometric MCI (pMCI) or CN based on standard and robust norms and "single-test" versus "multi-test" criteria. RESULTS: Prevalence of pMCI ranged from 3% to 49% depending on the classification scheme used. Those classified as pMCI using robust norms exhibited greater subjective cognitive complaints, diagnostic stability, and mild clinical symptoms at follow-up. CONCLUSIONS: Results suggest that identifying early clinically relevant cognitive decline in late middle-age is feasible using robust norms and multi-test criteria.

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