Living Alone, Early Tau Pathology, and Loneliness in Cognitively Unimpaired Older Adults During the COVID-19 Pandemic

Social restrictions during the COVID-19 pandemic heightened concerns about the negative health impacts of loneliness on older adults, particularly among those living alone. This study evaluated whether Alzheimer's disease (AD) pathology might be an underlying factor contributing to increased loneliness in cognitively unimpaired (CU) older adults living alone or with others during the pandemic.

One hundred-two CU participants from the Harvard Aging Brain Study completed pre-pandemic assessments of loneliness, cognition, cortical amyloid burden (PiB-PET), and tau pathology in inferior temporal (IT) and entorhinal cortical (EC) regions (FTP-PET). In May 2020, participants completed online surveys assessing living arrangements (alone versus with others) and current loneliness. Linear regressions estimated the interactive effects of living alone and either PiB, EC or IT FTP binding, or cognition on changes in loneliness, adjusting for age, sex, time since the pre-pandemic imaging, and pre-pandemic levels of depression, anxiety, and loneliness.

Participants living alone during the pandemic reported greater increases in loneliness compared to those living with others (β = 1.22, p = 0.024). Higher right EC and right IT FTP binding interacted with living alone to amplify this association (for the right EC FTP interaction, β = 4.14, p = 0.043, R² = 0.21; for the right IT FTP interaction, β = 7.16, p = 0.017, R² = 0.23). Other interactions of living alone with PiB-PET or cognition were not associated with change in loneliness.

Greater tau pathology amplified the association between living alone and increased loneliness among CU older adults during the COVID-19 pandemic. AD pathological brain changes may play an unrecognized role in late-life loneliness.