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Why do some people develop psychiatric disorders while others do not? Despite decades of research, this question remains difficult to answer. Psychiatric disorders are shaped by multiple, interacting influences, including genetics and environmental factors. Untangling how such risk factors work together remains a central challenge for the field (Burmeister et al. 2008), yet doing so could help improve diagnosis, treatment, and prevention.
Genome-wide association studies (GWAS) have identified many genetic variants linked with mental health, but these only account for a small fraction of heritability (Trubetskoy V et al. 2022; Demontis D et al. 2023; Donnelly N and Foley E, 2025). Mendelian randomization (MR) is a genetic…