Social environment, lifestyle, and genetic predisposition with dementia risk: A long-term longitudinal study among older adults

Shu Chen; Shanquan Chen; Katja Hanewald; Yafei Si; Hazel Bateman; Bingqin Lin; Xiaolin Xu; Suraj Samtani; Chenkai Wu; Henry Brodaty

doi:10.1093/gerona/glae128

Social environment, lifestyle, and genetic predisposition with dementia risk: A long-term longitudinal study among older adults

J Gerontol A Biol Sci Med Sci. 2024 May 11:glae128. doi: 10.1093/gerona/glae128. Online ahead of print.

Authors

Shu Chen^{1

2}, Shanquan Chen³, Katja Hanewald^{1

2}, Yafei Si^{1

2}, Hazel Bateman^{1

2}, Bingqin Lin⁴, Xiaolin Xu^{5

6}, Suraj Samtani⁷, Chenkai Wu⁸, Henry Brodaty^{7

9}

Affiliations

¹ School of Risk and Actuarial Studies, UNSW Sydney, NSW 2052, Australia.
² ARC Centre of Excellence in Population Ageing Research (CEPAR), 223 Anzac Parade, Kensington, NSW 2033, Australia.
³ International Centre for Evidence in Disability, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom.
⁴ Social Policy Research Centre UNSW Sydney, NSW 2052, Australia.
⁵ Department of Big Data in Health Science, School of Public Health, Zhejiang University, Hangzhou 310058, China.
⁶ Centre of Clinical Big Data and Analytics, The Second Affiliated Hospital Zhejiang University School of Medicine, Hangzhou 310009, China.
⁷ Centre for Healthy Brain Ageing (CHeBA), UNSW Sydney, NSW 2052, Australia.
⁸ Duke Kunshan University, Kunshan, Jiangsu 215316, China.
⁹ Dementia Centre for Research Collaboration, UNSW Sydney, NSW 2052, Australia.

PMID: 38733088
DOI: 10.1093/gerona/glae128

Abstract

Background: The role of social environment, i.e., the aggregate effect of social determinants of health (SDOHs), in determining dementia is unclear.

Methods: We developed a novel polysocial risk score for dementia based on 19 SDOH among 5,199 participants in the Health and Retirement Study, US, to measure the social environmental risk. We used a survival analysis approach to assess the association between social environment and dementia risk in 2006-2020. We further studied the interaction between social environment and lifestyles, and explored racial disparities.

Results: The study participants (mean age=73.4 years, SD=8.3; 58.0% female; 11.6% African American) were followed up for an average of 6.2 years, and 1,089 participants developed dementia. Every one-point increase in the polysocial risk score (ranging from 0-10) was associated with a 21.6% higher risk (aHR=1.21, 95% CI=1.15-1.26) of developing dementia, other things being equal. Among participants with high social environmental risk, regular exercise and moderate drinking were associated with a 43-60% lower risk of developing dementia (p<0.001). In addition, African Americans were 1.3 times (aHR=2.28, 95% CI=1.96-2.66) more likely to develop dementia than European Americans, other things being equal.

Discussion: An adverse social environment is linked to higher dementia risk, but healthy lifestyles can partially offset the increased social environmental risk. The polysocial risk score can complement the existing risk tools to identify high-risk older populations, and guide the design of targeted social environmental interventions, particularly focusing on improving the companionship of the older people, to prevent dementia.

Keywords: Dementia; lifestyle; polysocial risk score; racial disparities; social environment.

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