Age-related differences in Default Mode Network resting-state functional connectivity but not gray matter volume relate to sacrificial moral decision-making and working memory performance

Abstract

Older adults make fewer utilitarian decisions than younger adults during sacrificial moral dilemmas, which are associated with age-related reductions in Default Mode Network resting-state functional connectivity. Decreases on tasks associated with fluid cognitive abilities, such as working memory capacity, are also associated with age-related Default Mode Network changes. Regions within this network demonstrate some of the greatest age-related gray matter atrophy. Age-related changes in structure and function of the Default Mode Network may be associated with poorer working memory capacity and reduced utilitarian moral decision-making. Alternatively, recent theories suggest that age-related changes to Default Mode Network function may be adaptive in the context of tasks that include socioemotional components. As such, reduced within-network resting-state functional connectivity of the Default Mode Network may be associated with differential outcomes in moral decision-making for younger and older adults. In the present study, there were no age-related differences in working memory capacity. Older adults were less likely than younger adults to indicate the utilitarian option when trials involved Instrumental harm. Generally, increased within-network resting-state functional connectivity of the Default Mode Network was associated with better working memory performance in both groups, and reduced bias to endorse the utilitarian option during Incidental dilemmas compared to Instrumental dilemmas in younger adults. Older adults with similar moral decision-making behavior to younger adults demonstrated increased coupling between Default Mode Network and Salience Network regions. These findings suggest that Default Mode Network functional integrity may be differentially associated with age-related changes to working memory capacity and sacrificial moral decision-making.

Keywords: Aging; Default mode network; Morality; Working memory.