A Comprehensive Mendelian Randomization Study of Bidirectional Causal Relationships Between Pain and Mental Disorders

Area of Science:

• Genetics
• Psychiatry
• Epidemiology

Background:

• Pain and mental disorders frequently co-occur, but their causal relationship is unclear.
• Observational studies have limitations in establishing directionality and specificity.
• Mendelian randomization (MR) offers a method to investigate causal links between pain phenotypes and psychiatric outcomes.

Purpose of the Study:

• To investigate bidirectional causal relationships between various pain conditions and mental/personality disorders using MR.
• To assess the independence of these associations, accounting for comorbidities.
• To evaluate the robustness of findings through sensitivity analyses.

Main Methods:

• Bidirectional Mendelian randomization (MR) analysis.
• Multivariable MR to assess independence of associations.
• Sensitivity analyses for robustness.

Main Results:

• Several pain phenotypes (e.g., back pain, headaches, migraine) causally increase the risk of specific mental disorders.
• Mental disorders also causally predispose individuals to certain pain conditions.
• Associations were largely robust but sometimes attenuated by obesity or substance use.

Conclusions:

• Demonstrates specific, bidirectional relationships between pain types and mental disorders.
• Supports phenotype-informed screening and management for integrated care.
• Highlights the need for targeted assessment of mental health in pain patients and vice versa.