Why might urban tree canopy reduce dementia risk? A causal mediation analysis of 109,688 adults with 11 years of hospital and mortality records

Thomas Astell-Burt; Michael A Navakatikyan; Xiaoqi Feng

doi:10.1016/j.healthplace.2023.103028

Why might urban tree canopy reduce dementia risk? A causal mediation analysis of 109,688 adults with 11 years of hospital and mortality records

Health Place. 2023 Jul:82:103028. doi: 10.1016/j.healthplace.2023.103028. Epub 2023 May 12.

Authors

Thomas Astell-Burt¹, Michael A Navakatikyan², Xiaoqi Feng³

Affiliations

¹ Population Wellbeing and Environment Research Lab (PowerLab), NSW, Australia; School of Health and Society, University of Wollongong, Northfields Avenue, Wollongong, Australia. Electronic address: thomasab@uow.edu.au.
² Population Wellbeing and Environment Research Lab (PowerLab), NSW, Australia; School of Health and Society, University of Wollongong, Northfields Avenue, Wollongong, Australia.
³ Population Wellbeing and Environment Research Lab (PowerLab), NSW, Australia; School of Population Health, University of New South Wales, Sydney, Australia; The George Institute of Global Health, Sydney, NSW, Australia.

PMID: 37182375
DOI: 10.1016/j.healthplace.2023.103028

Abstract

Urban tree canopy is associated with lower dementia risk, but no mediation analysis has been attempted to reveal potential mechanisms. We examined 3,639 dementia diagnoses in 109,688 participants of the Sax Institute's 45 and Up Study. Adjusted models indicated ≥20% tree canopy lowered the odds of developing dementia by 14% over 11 years (Odds Ratio = 0.86, 95%CI = 0.79-0.93). Association between tree canopy and dementia was partially mediated by physical activity (4.5%) and absences of psychological distress (5.7%), social support (2.9%), sleep duration (2.3%) and diabetes (1.8%). Social loneliness and absence of heart disease or hypertension did not mediate the tree canopy-dementia association.

Keywords: Alzheimer's disease; Green space; Longitudinal cohort study; Mediation; Nature.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Dementia*
Hospitals
Humans
Loneliness
Mediation Analysis
Trees*