A Two-Sample Mendelian Randomization Study of Neuroticism and Sleep Bruxism.

Area of Science:

• Psychiatry and Genetics
• Sleep Medicine

Background:

• Sleep bruxism (SB) is prevalent and linked to psychological factors like neuroticism, stress, and anxiety.
• Existing research on risk factors for SB is often limited by sample size and methodology, hindering causal inference.
• Understanding the causal mechanisms between neuroticism and SB is crucial for effective management of SB and related conditions.

Purpose of the Study:

• To investigate the potential causal relationship between neuroticism and sleep bruxism (SB) using a large-scale Mendelian randomization (MR) approach.
• To combine genetic data with questionnaire and registry information for robust analysis of risk factors for SB.
• To explore specific neuroticism subcategories contributing to SB risk.

Main Methods:

• A two-sample Mendelian randomization (MR) study was conducted.
• Instrumental genetic variants for neuroticism were sourced from the UK Biobank (n = 380,506).
• Outcome data for probable sleep bruxism (SB) were obtained from FinnGen (n [cases/controls] = 12,297/364,980).

Main Results:

• A significant causal effect of neuroticism on sleep bruxism (SB) was identified (Odds Ratio [OR] = 1.38, P = 0.0057).
• A phenotype sensitive to stress and adversity showed the strongest causal effect (OR = 1.59, P = 0.0028).
• Sensitivity analyses confirmed the causal relationship, and no significant pleiotropy was detected between neuroticism and SB (MR-Egger intercept P = 0.87).

Conclusions:

• Neurotic traits are causally associated with an increased risk of probable sleep bruxism (SB).
• These findings support previous observational studies linking stress and SB.
• The results highlight neuroticism as a significant risk factor for sleep bruxism.