RecruitingPhase 3Behavioural interventionPreventing Alzheimer's With Cognitive TrainingDementia is the most expensive medical condition in the US and increases in prevalence with age. More than 5 million Americans have Alzheimer's disease, the most common form of dementia. Mild cognitive impairment is a transitional stage between normal cognitive aging and Alzheimer's disease or another type of dementia, and is indicative of higher risk for dementia. In addition to the obvious health and quality-of-life ramifications of dementia, there are high direct (e.g., subsidizing residential care needs) and indirect (e.g., lost productivity of family caregivers) economic costs. Implementing interventions to prevent MCI and dementia among older adults is of critical importance to health and maintained quality-of-life for millions of Americans. Recent data analyses from the Advanced Cognitive Training in Vital Elderly study (ACTIVE) indicate that a specific cognitive intervention, speed of processing training (SPT), significantly delays the incidence of cognitive impairment across 10 years. The primary contribution of the proposed research will be the determination of whether this cognitive training technique successfully delays the onset of clinically defined MCI or dementia across three years.