A large population-based cross-sectional study has found that central body fat, particularly around the abdomen, is strongly linked to a higher risk of developing psoriasis.
The study analyzed data from 336,806 UK participants and identified waist-to-hip ratio and abdominal fat as key predictors of the condition, with the association especially pronounced in women.
Researchers evaluated 25 measures of body fat using standard physical metrics, bioelectric impedance, MRI, and dual-energy X-ray absorptiometry (DEXA). Percentage body fat measured by bioelectric impedance showed the strongest association with psoriasis. Among distribution measures, four of the five strongest associations were related to central adiposity: waist-to-hip ratio, abdominal fat ratio, total abdominal adipose tissue index, and waist circumference.
The study included 9305 individuals with psoriasis. Researchers observed that central adiposity had a stronger association with psoriasis in women than in men. For example, visceral adipose tissue mass showed a significantly stronger association in females (interaction with sex P = 6.70e-03), suggesting possible sex-specific differences, though the underlying mechanisms remain unclear.
Genetic factors were also assessed. Using a polygenic risk score based on 109 psoriasis-related variants, the study tested whether fat distribution interacted with genetic susceptibility. Central adiposity remained a risk factor even in individuals with lower genetic risk. The waist-to-hip ratio had a stronger association in participants lacking the psoriasis-linked gene HLA-C*06:02, although further analysis indicated this might reflect statistical bias rather than a true gene-environment interaction.
To assess causality, researchers used Mendelian randomization, a method that employs genetic variations as natural proxies for randomized trials. Results supported a likely causal role for central adiposity in increasing psoriasis risk, independent of genetic background.
Psoriasis cases were identified through self-reported data, hospital records, and primary care diagnoses. While dermatologist-confirmed diagnoses were not available, sensitivity analyses excluding primary care data showed consistent results, helping to reduce the risk of misclassification.
The study population was limited to White British individuals, which may affect the generalizability of the findings. Additionally, imaging-based measures were available only in a small subset of participants, potentially limiting the statistical power of some analyses.
Nonetheless, the findings suggest that central adiposity is a significant and independent contributor to psoriasis risk. These insights could inform future approaches to identifying at-risk individuals and integrating weight management into psoriasis prevention and care strategies.
Full disclosures can be found in the study.
