Abstract
BACKGROUND: Better cognitive tools to predict disease progression in mild cognitive impairment (MCI) and Alzheimer's disease (AD) are needed. OBJECTIVE: In this prospective longitudinal cohort, we are testing if changes in the cognitive domains of executive functioning and processing speed can predict global cognitive decline. METHODS: We assessed patients with MCI, AD, and cognitively healthy controls (cHC) using NIH toolbox assessments for processing speed and executive functioning and overall cognitive decline by the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-Cog). RESULTS: Among 184 participants over a median follow-up of 540 days, both between- and within-subjects variance in NIH toolbox and ADAS-Cog assessments increased from cHC to MCI to AD patients. Among patients with AD (n = 24), pattern comparison processing speed (PCPS) and dimensional change card sort tests (DCCS) declined at 3 and 6 months prior to global cognitive decline (p = 0.008 and 0.0012). A 5-point decrease in either PCPS or DCCS increased risk of global cognitive decline (HR 1.32 (1.08-1.60) and 1.62 (1.16-2.26)). CONCLUSIONS: Testing for cognitive domains of processing speed and executive functioning may predict subsequent global cognitive.