Trajectories of Cognitive Decline Among Black Americans: The Role of Social Isolation

Background and Purpose: The prevalence of Alzheimer’s disease and related dementias (ADRD) among Black adults is 2-3 times greater than that of white adults. Research points to numerous modifiable risk factors for ADRD, including social isolation. Yet most ADRD research focuses on the predominately white general population or specifically on older white adults. Thus, there is a dearth of knowledge on ADRD and its risk factors specifically among older Black adults. A better understanding of these risk factors is imperative for eliminating this racial disparity. Social isolation, which is linked to poor cognitive function, cognitive decline, and dementia is a particularly important risk factor for older Black adults, as this group is exposed to more factors that increase their risk for social isolation. The aims of this study are to 1) identify cognitive decline trajectories among middle-aged and older Black adults and 2) determine whether social isolation can lead to worse trajectories of cognitive decline.

Methods: Data for the study came from a nationally representative sample of Black participants aged 51+ in the Health and Retirement Study (N=1791). This longitudinal analysis used data from 2006-2020. Cognitive status was measured using the modified Telephone Interview for Cognitive Status. Social isolation from extended family, children, and friends were measured using indicators of network size, contact, and social support for each social group. Control variables included age, sex, education, marital status, and living arrangement. Group-based trajectory analysis was used.

Results: The analysis identified 4 distinct cognitive decline trajectories over the 12-year study period—very low and declining; low and declining; moderate and stable; high and stable. The multivariable analysis indicated that people who were socially isolated from friends were more likely to belong to the very low and declining, low and declining, or moderate and stable trajectory than the high and stable trajectory. However, social isolation from extended family and social isolation from children did not predict cognitive decline trajectories.

Conclusions and Implications: Social isolation is a major public health problem, and the U.S. Surgeon General recently declared social isolation a public health epidemic. This study contributes to the limited literature on modifiable risk factors for cognitive decline specifically among older Black adults. These findings argue for a more nuanced and systematic investigation of the effects of social isolation on middle-aged and older Black Americans’ cognitive health. Efforts to tailor social isolation interventions to specific client populations could prove especially pertinent and important for social work practices with Black clients, especially older Black clients.