Cognitively stimulating environments and cognitive reserve: the case of personal social networks.

Cognitively stimulating environments are thought to be protective of cognitive decline and onset of Alzheimer's disease and related dementias (ADRD) through the development of cognitive reserve (CR). CR refers to cognitive adaptability that buffers the impact of brain pathology on cognitive function. Despite the critical need to identify cognitively stimulating environments to build CR, there is no consensus regarding which environmental determinants are most effective. Rather, most studies use education as proxies for CR and little is known about the association between older adults' personal social networks and CR. Using neuroimaging data from 135 older adults participating in the Social Networks in Alzheimer Disease (SNAD) study, this article adopted a residual method for measuring CR and found that large network size, high network diversity, and loosely connected networks were positively associated with greater CR. These results suggest that expansive social networks in later life may constitute cognitively stimulating environments which can be leveraged to build CR and reduce the burden of ADRD.