Cardiorespiratory fitness is associated with atrophy in Alzheimer's and aging over 2 years

We sought to describe change in cardiorespiratory (CR) fitness over 2 years in those with early-stage Alzheimer's disease (AD) and nondemented aging and assess the relationship of CR fitness with cognitive decline, brain atrophy, and dementia progression. Individuals with early-stage AD (n = 37) and without dementia (n = 53) attended clinical evaluations, cognitive and exercise tests, and magnetic resonance imaging (MRI) at baseline and 2 years later. CR fitness was lower in those with AD over the study period. Lower baseline CR fitness was associated with progression of dementia severity in AD. Declining CR fitness over 2 years was associated with brain atrophy in AD, especially in the parahippocampus. In nondemented participants, there was a trend for lower baseline fitness to be related to cognitive decline. Both lower baseline CR fitness and declining CR fitness over 2 years were associated with regional brain atrophy. We conclude that CR fitness is chronically reduced in those with AD. Further, in those with AD, CR fitness is associated with progression of dementia severity and brain atrophy in AD, suggesting a link between progression of dementia severity and cardiorespiratory health.