NPJ Parkinsons Dis. 2021 Jan 5;7(1):5. doi: 10.1038/s41531-020-00145-8.

Bojing Liu ¹, Arvid Sjölander ², Nancy L Pedersen ^2 3, Jonas F Ludvigsson ^2 4 5 6, Honglei Chen ⁷, Fang Fang ⁸, Karin Wirdefeldt ^2 9

Author information

• ¹Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden. bojing.liu@ki.se.
• ²Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
• ³Department of Psychology, University of Southern California, Los Angeles, CA, USA.
• ⁴Department of Paediatrics, Örebro University Hospital, Örebro, Sweden.
• ⁵Division of Epidemiology and Public Health, School of Medicine, University of Nottingham, Nottingham, UK.
• ⁶Celiac Disease Center, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA.
• ⁷Department of Epidemiology and Biostatistics, College of Human Medicine, Michigan State University, East Lansing, MI, USA.
• ⁸Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
• ⁹Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.

Abstract

To examine whether irritable bowel syndrome (IBS) was related to the future risk of Parkinson's disease (PD), we conducted a nested case-control study in the Swedish total population including 56,564 PD cases identified from the Swedish Patient Register and 30 controls per case individually matched by sex and year of birth. Odds ratios (ORs) with 95% confidence intervals (CIs) for having a prior diagnosis of IBS were estimated using conditional logistic regression. We furthermore conducted a cohort study using the Swedish Twin Registry following 3046 IBS patients identified by self-reported abdominal symptoms and 41,179 non-IBS individuals. Through Cox proportional hazard models, we estimated hazard ratios (HRs) and 95% CIs for PD risk. In the nested case-control study, 253 (0.4%) PD cases and 5204 (0.3%) controls had a previous IBS diagnosis. IBS diagnosis was associated with a 44% higher risk of PD (OR = 1.44, 95% CI 1.27-1.63). Temporal relationship analyses showed 53% and 38% increased risk of PD more than 5 and 10 years after IBS diagnosis, respectively. In the cohort analysis based on the Swedish Twin Registry, there was no statistically significantly increased risk of PD related to IBS (HR = 1.25, 95% CI = 0.87-1.81). Our results suggest a higher risk of PD diagnosis after IBS. These results provide additional evidence supporting the importance of the gut-brain axis in PD.