Constipation and Psychiatric Disorders: A Bidirectional Mendelian Randomization Study.

BACKGROUND

Observational studies have shown a link between constipation (CN) and psychiatric disorders, including Schizophrenia (SP), Bipolar disorder (BD), Schizoaffective disorder (SD), and Parkinson's disease (PD). However, it is still unknown whether CN affects the occurrence and development of psychiatric disorders or whether psychiatric disorders cause the occurrence and development of CN. Therefore, this study used Mendelian randomization (MR) analysis to evaluate the relationship between CN and psychiatric disorders.

METHOD: We used genome-wide association studies (GWAS) to assess the relationship between constipation (N = 411, 623) and four psychiatric disorders, including SP ( N = 77, 096), BD (N = 51, 710), SD ( N = 210, 962), PD (N = 482, 730 ), using bidirectional MR analysis. Inverse variance weighting (IVW), MR Egger (ME) and Weighted median (WM) were used as causal analysis methods. Cochran's Q test, funnel plot, MR Egger intercept test and Leave.one.out analysis were used to detect sensitivity. Confounding factors were analyzed and eliminated by LDtrait to avoid influencing the final MR Analysis result.

RESULTS

The results of positive MR analysis indicated that there was no evidence of influence of constipation on SP (OR 1.043, 95%CI 0.946 - 1.149, P value = 0.398), BD (OR 1.114, 95%CI 0.995 - 1.248, P value = 0.062), SD (OR 0.934, 95%CI 0.674 - 1.294, P value = 0.682) and PD (OR 1.118, 95%CI 0.918 - 1.361, P value = 0.269) under gene prediction. Reverse MR analysis suggested that SP (OR 1.030, 95% CI 1.001-1.060, P value = 0.042) had a causal relationship with constipation. BD (OR 0.993, 95% CI 0.962-1.025, P value = 0.664), SD (OR 1.021, 95% CI 0.984-1.059, P value = 0.265) and PD (OR 1.004, 95% CI 0.974-1.035, P value = 0.790) were not associated with CN.

CONCLUSION

There was a positive association between SP and CN. CN may have no exact causal relationship with BD, SD and PD, and the interaction mechanism between these diseases needs to be further explored.