Daily function outcomes in adults with mild cognitive impairment due to Alzheimer's disease after two years of processing speed training versus a control training protocol

Background Cognitive processing speed is integral to everyday activities and can be improved with training in persons with mild cognitive impairment (MCI). However, whether this training maintains everyday abilities is not known. Objective We aimed to determine whether everyday functions key to independence could be preserved with two years of processing speed training. Methods In a randomized controlled trial, we objectively evaluated a processing speed training protocol compared to a control training protocol, in 103 persons with MCI (n = 90) or very mild dementia (n = 13) due to Alzheimer's disease (AD). Each protocol involved serial assessments, laboratory training, and home training over a two-year period. We accounted for APOE ε4 carrier status and MRI-based neurodegeneration conducted at baseline. Outcomes were longitudinal changes in performance-based Instrumental Activities of Daily Living (IADLs), community mobility, and on-road driving. We used linear mixed models to evaluate changes in these outcomes over time. Results Changes in IADL function, driving, and community mobility did not differ by training assignment. Greater baseline neurodegeneration predicted larger declines in all functional outcomes ( p values < 0.001). Conclusions In persons with MCI or very mild dementia, processing speed training was no more effective for maintaining everyday functions than training involving common computer activities and games that do not target processing speed. Greater baseline neurodegeneration predicted worse performance over time on all measures of function.