Autoimmune thyroid disease is a risk factor for mood disorders, a Mendelian randomization study.

Area of Science:

• Genetics
• Psychiatry
• Endocrinology

Background:

• Observational studies suggest links between autoimmune thyroid disease and mood disorders/dementia.
• Causality between these conditions remains unclear.

Purpose of the Study:

• To investigate the causal relationships between autoimmune thyroid disease (Graves' disease, autoimmune thyroiditis) and mood disorders (major depressive disorder, bipolar disorder) or dementia using Mendelian randomization.

Main Methods:

• Bidirectional, two-sample Mendelian randomization analyses were performed.
• Genome-Wide Association Study data from Finngen and IEU Open GWAS were utilized.
• Robust statistical methods and sensitivity analyses were employed to ensure validity.

Main Results:

• Graves' disease showed an association with an increased risk of major depressive disorder (P=0.02).
• Autoimmune thyroiditis was linked to a greater risk of bipolar disorder (P=0.043).
• No causal link was found between autoimmune thyroid disease and dementia, nor did mood disorders increase autoimmune thyroid disease risk.

Conclusions:

• Graves' disease is associated with a heightened risk of major depressive disorder.
• Autoimmune thyroiditis is correlated with an increased risk of bipolar disorder.