The bidirectional causal association between psoriasis and psychological illnesses: a 2-sample Mendelian...

Area of Science:

• Genetics
• Psychiatry
• Dermatology

Background:

• Observational studies suggest an association between psoriasis and psychological illnesses, but establishing causality is challenging.
• High-quality evidence is needed to understand the complex relationship between skin conditions and mental health.

Purpose of the Study:

• To evaluate the causal relationship between psoriasis and psychological illnesses using a robust genetic approach.
• To determine if psoriasis causes psychological distress or if psychological factors contribute to psoriasis development.

Main Methods:

• Summary-level data from genome-wide association studies (GWAS) for psoriasis and psychological illnesses were utilized.
• Bidirectional Mendelian randomization analysis was performed using established statistical methods (Inverse-Variance Weighted, weighted median, MR Egger).
• Sensitivity analyses and cross-dataset validation were conducted to ensure result reliability.

Main Results:

• Mendelian randomization analysis revealed a significant causal effect of psoriasis on psychological illnesses (ORs ranging from 1.28 to 1.34).
• A significant causal effect of psychological illnesses on psoriasis was also identified (ORs ranging from 1.21 to 1.23).
• Results were consistent across different analytical methods and validated by sensitivity analyses.

Conclusions:

• This study provides strong evidence supporting a bidirectional causal relationship between psoriasis and psychological illnesses.
• The findings highlight the importance of considering the psychological impact in psoriasis management and vice versa.