# Spatial distribution of residential environment, genetic susceptibility, and psoriasis: A prospective cohort study

## TL;DR

Living near natural and green areas may increase psoriasis risk, while proximity to blue spaces and gardens may reduce it, with genetic factors playing a modifying role.

## Contribution

This study is the first to explore the interaction between genetic susceptibility and residential environments in relation to psoriasis risk.

## Key findings

- Higher exposure to natural environments and green spaces was linked to increased psoriasis risk.
- Exposure to blue spaces and domestic gardens was associated with reduced psoriasis risk.
- Genetic risk modified the relationship between residential environments and psoriasis risk.

## Abstract

Genetic and environmental factors contribute to psoriasis, but the impact of residential environments on this condition remains uncertain. We aimed to investigate the association of residential environments with psoriasis risk and explore its interaction with genes.

We retrieved data on the spatial distribution of residential environments at 300 and 1000 m buffer zones from the UK Biobank, including the proportions of natural environments, domestic gardens, green spaces, and blue spaces within these zones. We then used Cox hazard models to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between residential environments and psoriasis risk. Lastly, we constructed polygenic risk scores to determine genetic susceptibility and further analyse the interaction with residential environments.

Overall, 3755 incident cases of psoriasis were documented during a median follow-up of 12.45 years. Compared with the lowest exposure quantile (Q1), Q4 exposure to natural environments (1000 m buffer: HR = 1.16, 95% CI = 1.05–1.29; 300 m buffer: HR = 1.12, 95% CI = 1.02–1.24) and green spaces (1000 m buffer: HR = 1.16, 95% CI = 1.04–1.28; 300m buffer: HR = 1.10, 95% CI = 1.00–1.21) increased the risk of psoriasis, while Q4 exposure to domestic gardens (1000 m buffer: HR = 0.85, 95% CI = 0.77–0.93; 300m buffer: HR = 0.91, 95% CI = 0.83–1.00) and Q3 exposure to blue spaces (1000 m buffer: HR = 0.89, 95% CI = 0.81–0.98) were negatively associated with psoriasis risk. Among participants with a high genetic risk, those exposed to high levels of natural environments (1000 m buffer: HR = 1.49, 95% CI = 1.15–1.93; 300 m buffer: HR = 1.39, 95% CI = 1.10–1.77) and green spaces (300 m buffer: HR = 1.30, 95% CI = 1.04–1.64) had a higher risk of psoriasis, while those exposed to blue spaces (1000 m buffer: HR = 0.78, 95% CI = 0.63–0.98) had a lower risk of psoriasis. We also observed joint effects of genetic risk and residential environments and an antagonistic additive interaction between blue spaces and genetic risk (P = 0.011).

We observed that residing in natural environments and green areas increased the risk of psoriasis in our sample, while proximity to blue spaces and domestic gardens was associated to reduced risks. The association of residential environments with psoriasis risk was modified by genetic susceptibility.