A Study on Lifestyle and Dietary Factors in Psoriasis: Global Prevalence Trends in Working-Age Populations, Association with LE4 Lifestyle Factors, and Mendelian Randomization Analysis of Dietary Causal Effects

Background: Psoriasis is a chronic immune-mediated skin disease influenced by genetic, environmental, and lifestyle factors, with increasing burden among working-age adults. Objective: To examine global trends in psoriasis prevalence among working-age adults, evaluate associations with lifestyle factors using a simplified Life’s Essential 4 (LE4) index, and explore potential dietary causal relationships through Mendelian randomization (MR). Methods: Global prevalence trends from 1990 to 2021 were analyzed using GBD 2021 data, calculating age-standardized rates (ASR) and estimated annual percentage changes (EAPC), with projections to 2031. Regional variations across SDI levels were also assessed. The LE4 index, derived from core lifestyle components of the Life’s Essential 8 framework using NHANES data, was evaluated via survey-weighted logistic regression and restricted cubic spline analysis. Two-sample MR analyses were conducted using the inverse-variance weighted (IVW) method to assess dietary traits. Results: The global prevalence of psoriasis among working-age adults increased from 555.7 to 600.6 per 100,000 (EAPC: 0.22%), with projections reaching 631.6 by 2031; Notably, upward trends were consistently observed across all SDI regions. Higher LE4 scores (≥ 81.2) were associated with lower odds of psoriasis (OR: 0.518, P=0.040). MR analyses suggested that genetically predicted fizzy drink consumption increased risk (OR: 1.57, P=0.0215), whereas salad vegetable intake showed a protective association (OR: 0.85, P=0.0224). Conclusion: The burden of psoriasis among working-age adults shows a modest global increase with regional heterogeneity. Healthier lifestyle patterns and favorable dietary factors were associated with reduced risk, highlighting the importance of modifiable behaviors in prevention strategies. Keywords: psoriasis, epidemiology, lifestyle, mendelian randomization, global burden of disease