Bidirectional two-sample Mendelian randomization analysis identifies causal associations between relative...

Area of Science:

• Nutritional Psychiatry
• Genetic Epidemiology
• Metabolic Health

Background:

• The relationship between carbohydrate consumption and depression is debated.
• Understanding this link is crucial for public health and mental wellness.
• Previous studies have yielded conflicting results on carbohydrate intake and depression risk.

Purpose of the Study:

• To investigate the causal association between relative carbohydrate intake and major depressive disorder.
• To explore potential mediating factors, such as body mass index, in this relationship.
• To provide evidence for dietary strategies in depression prevention.

Main Methods:

• Utilized a two-sample bidirectional Mendelian randomization (MR) analysis.
• Employed large-scale genome-wide association study data for carbohydrate intake (N=268,922) and depression (N=143,265).
• Conducted multivariable MR and two-step MR for mediation analysis.

Main Results:

• Mendelian randomization indicated a significant protective effect of higher relative carbohydrate intake on depression risk (OR=0.42, P=1.49×10^-5).
• This protective association remained significant after adjusting for other dietary factors.
• Body mass index partially mediated the effect, accounting for 15.4% of the association.

Conclusions:

• Findings support a causal link between higher relative carbohydrate intake and lower depression risk.
• Dietary interventions focusing on carbohydrate intake may be beneficial for depression prevention.
• Body mass index plays a partial role in mediating the protective effects of carbohydrates on depression.