Physical activity as a potential nonpharmacologic strategy to prevent seborrheic dermatitis: a cohort study in the UK biobank

BACKGROUND: Seborrheic dermatitis (SD) is a chronic inflammatory skin disease with limited long-term treatment options. The association between physical activity and incident SD, as well as the potential mediating role of depressive symptoms, remains unclear. OBJECTIVE: To investigate the association between physical activity and incident SD and to assess whether depressive symptoms mediate this relationship. METHODS: Data from 396,903 participants in the UK Biobank were analyzed. Cox proportional hazards models were used to examine the association between physical activity and incident SD. Regression-based mediation analyses were performed to quantify the extent to which depressive symptoms mediated this association. RESULTS: Physical activity above the recommended minimum (≥600 MET-min/week) was associated with a lower risk of incident SD. The greatest risk reduction was observed at 3-5 times the recommended level (1,800-3,000 MET-min/week; HR 0.80, 95% CI 0.71-0.90). Participants meeting criteria for healthy physical activity had a 28% lower risk of incident SD (HR 0.72, 95% CI 0.64-0.81). Mediation analyses showed that 17% of the protective association was explained by reduced depressive symptoms (indirect HR 0.83, 95% CI 0.77-0.88), while 16% was attributable to the direct effect of physical activity (direct HR 0.84, 95% CI 0.77-0.93). CONCLUSIONS: Physical activity may serve as a non-pharmacologic strategy for the prevention of SD, partly through alleviating depressive symptoms. The maximal benefit was observed at 3-5 times the recommended minimum activity level.