Causal Relationship Between Inflammatory Bowel Disease and Neuropsychiatric Disorders: A Bidirectional Mendelian...

Area of Science:

• Genetics and Epidemiology
• Neuroscience
• Gastroenterology

Background:

• Observational studies suggest a link between inflammatory bowel disease (IBD) and neuropsychiatric disorders.
• The causal nature of this association remains undetermined.

Purpose of the Study:

• To investigate the potential causal relationship between IBD and seven major neuropsychiatric disorders using a bidirectional two-sample Mendelian randomization (MR) approach.
• To explore potential causal links between subtypes of IBD, Crohn's disease (CD) and ulcerative colitis (UC), and neuropsychiatric conditions.

Main Methods:

• Utilized genome-wide association study (GWAS) summary statistics from European ancestry.
• Performed bidirectional two-sample MR analysis for IBD (including CD and UC) and major depressive disorder (MDD), bipolar disorder (BD), schizophrenia (SCZ), Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS).
• Conducted sensitivity analyses to ensure the robustness of the findings.

Main Results:

• Identified potential positive causal effects of IBD and CD on MDD and SCZ.
• Found a positive association between SCZ and increased risk of IBD and UC.
• Observed a bidirectional positive association between IBD, UC, and MS, with CD also showing a positive causal effect on MS.
• No evidence was found for causal effects of MDD, BD, AD, PD, or ALS on IBD or UC.

Conclusions:

• Results support potential causal relationships between IBD (CD and UC) and several neuropsychiatric disorders.
• Findings reinforce the concept of the gut-brain axis.
• Enhances understanding of extra-intestinal manifestations in IBD and neuropsychiatric aspects within IBD patients.