Disparities in neighbourhood characteristics and 10-year dementia risk by nativity status.

Aims: Prior research indicates that neighbourhood disadvantage increases dementia risk. There is, however, inconclusive evidence on the relationship between nativity and cognitive impairment. To our knowledge, our study is the first to analyse how nativity and neighbourhood interact to influence dementia risk.

Methods: Ten years of prospective cohort data (2011-2020) were retrieved from the National Health and Aging Trends Study, a nationally representative sample of 5,362 U.S. older adults aged 65+. Cox regression analysed time to dementia diagnosis using nativity status (foreign- or native-born) and composite scores for neighbourhood physical disorder (litter, graffiti and vacancies) and social cohesion (know, help and trust each other), after applying sampling weights and imputing missing data.

Results: In a weighted sample representing 26.9 million older adults, about 9.5% (n = 2.5 million) identified as foreign-born and 24.4% (n = 6.5 million) had an incident dementia diagnosis. Average baseline neighbourhood physical disorder was 0.19 (range 0-9), and baseline social cohesion was 4.28 (range 0-6). Baseline neighbourhood physical disorder was significantly higher among foreign-born (mean = 0.28) compared to native-born (mean = 0.18) older adults (t = -2.4, p = .02). Baseline neighbourhood social cohesion was significantly lower for foreign-born (mean = 3.57) compared to native-born (mean = 4.33) older adults (t = 5.5, p < .001). After adjusting for sociodemographic, health and neighbourhood variables, foreign-born older adults had a 51% significantly higher dementia risk (adjusted hazard ratio = 1.51, 95% CI = 1.19-1.90, p < .01). There were no significant interactions for nativity with neighbourhood physical disorder or social cohesion.

Conclusions: Our findings suggest that foreign-born older adults have higher neighbourhood physical disorder and lower social cohesion compared to native-born older adults. Despite the higher dementia risk, we observed for foreign-born older adults, and this relationship was not moderated by either neighbourhood physical disorder or social cohesion. Further research is needed to understand what factors are contributing to elevated dementia risk among foreign-born older adults.