Functional neuroimaging as a tool to understand social determinants of health in cognitive aging and ADRD: a scoping review

The social, structural, and physical conditions in which individuals live, work, and age, collectively termed social determinants of health (SDOH), are associated with risk of Alzheimer's disease and related dementias (ADRD). Differences in brain function in later life may offer understanding of how SDOH become biologically embedded and confer differential ADRD risk. However, how functional neuroimaging techniques have been used to study SDOH in cognitive aging and ADRD has yet to be systematically characterized. We therefore conducted a scoping review. Three databases were searched, 2,930 articles were screened, and 41 studies were included. Education was the most frequently studied SDOH domain, accounting for 65.9% (k = 27) of studies, followed by economic and occupation (k = 9, 22.0%), social and community (k = 5, 12.2%), food (k = 4, 9.8%), and physical environment (k = 3, 7.3%). Of the 41 studies, five (12.2%) examined multidomain determinants and one study (2.4%) examined three determinants each from different domains. Functional magnetic resonance imaging (fMRI) was most frequently employed (k = 31, 75.6%), followed by electroencephalography (EEG; k = 7, 17.1%), and magnetoencephalography (MEG; k = 4, 9.8%). One study (2.4%) employed a multimodal approach, while none used functional near-infrared spectroscopy. Resting state paradigms (k = 27, 65.9%) outnumbered task-based (k = 14, 34.1%) and most studies were cross-sectional (k = 38, 92.7%). The predominant focus on education, fMRI, and cross-sectional designs highlights many opportunities for future investigation of how SDOH may be associated with later life brain function.