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Dementia and Social Isolation among Older Adults across 11 years:
A Bidirectional Relationship

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T. Hou, M. Ho, and C. Lin 1
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School of Nursing, Li Ka Shing Faculty of Medicine, The University of Hong Kong, China

Background: Although social isolation has been associated with worse cognitive function among
older adults, the temporal relationship between the two remains subject to debate.

Objective: This study aims to investigate the longitudinal impact of dementia on social isolation and
vice versa.

Methods: We used National Health and Aging Trends Study (NHATS) participants from the 2011 to 2021
waves. Two cohorts were classified according to whether they had social isolation at baseline and
whether they had dementia at baseline, respectively. Cox proportional hazards regression models
evaluated the impact of baseline social isolation on subsequent dementia and the impact of
baseline dementia on subsequent social isolation. Models were adjusted for potential covariates,
Oral Presentation Abstracts
including demographics, health-related and behavioral factors.

Results: The first cohort involved participants with an average age of 74.6 ± 6.5 years, 59.5% were
female, 68.8% were non-Hispanic white, 72.4% had less than bachelor’s education, and 12.7% had
possible/probable dementia in older adults without social isolation at baseline. In the second cohort,
approximately 20.7% of participants had social isolation in the first wave, and they tended to be
female (58.3%) and non-Hispanic White (71.4%) in older adults without dementia. In fully adjusted Cox
regression models, participants with dementia had a higher likelihood of developing social isolation
over subsequent follow-up (HR, 1.4; 95% confidence interval, 1.17–1.67; P < 0.001). Moreover, participants
with baseline social isolation had a higher likelihood of developing dementia over time (HR, 7.2; 95%
confidence interval, 6.12-8.36; P < 0.001).

Conclusion: Social isolation was associated with greater dementia likelihood over time, and dementia
is similarly associated with greater social isolation over time. Awareness of this bidirectional
association may improve prevention and delay the onset of social isolation and dementia.

Keywords: dementia, social isolation, older adults

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Correspondence: Chia-Chin Lin, School of Nursing, Li Ka Shing Faculty of Medicine, The University of
Hong Kong, Hong Kong SAR
E-mail: cclin@hku.hk

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