Moderation between resting-state connectivity and brain amyloid levels on speed of cognitive and physical function in older adults: Evidence for network-based cognitive reserve.

Cognitive and physical function are interrelated in aging. Co-occurring impairments in both domains can be debilitating and lead to increased risk of developing dementia. Amyloid beta (Aβ) deposition in the brain is linked to cognitive decline and is also associated with poorer physical function in older adults. However, significant inter-individual variability exists with respect to the influence of increased brain Aβ concentrations on cognitive and physical outcomes. Identifying factors that explain inter-individual variability in associations between Aβ and clinical outcomes could inform interventions designed to delay declines in both cognitive and physical function. Cognitive reserve (CR) is considered a buffer that allows for cognitive performance that is better than expected for a given level of brain injury or pathology. Although the neural mechanisms underlying CR remain unknown, there is growing evidence that resting-state brain networks may serve as a neural surrogate for CR. The current study utilized a statistical interaction model to evaluate if functional brain networks moderated associations between brain Aβ and cognitive and physical function in community-dwelling older adults from the Brain Networks and Mobility (B-NET) study. Significant moderations were found between Aβ levels and both the central executive and subcortical networks with cognitive and physical function. The findings suggest that brain networks serve as a buffer against the influence of Aβ accumulation on cognitive and physical function indicating that the network integrity could one of the neural mechanisms supporting CR.