May 25, 2018
By Anne Harding
NEW YORK (Reuters Health) - People with inflammatory bowel disease (IBD) are at increased risk of developing Parkinson's disease (PD), according to new research using Danish registry data.
The results support the "gut-brain axis" theory, which proposes that the intestinal environment affects central nervous system (CNS) function, Dr. Tomasz Brudek of Bispebjerg and Frederiksberg Hospital in Copenhagen and his colleagues write in Gut, online May 21.
"Our findings contribute further to the paradigm shift of considering parkinsonism not just as CNS disorders, but as a group of diseases that may have their onset in the periphery, particularly, the gastrointestinal tract," Dr. Brudek told Reuters Health by email. "IBD is characterized by chronic pro-inflammatory immune activity, which has gained importance as a fundamental element in neurodegenerative disorders. Therefore, intestinal inflammation is of particular relevance in the pathogenesis of Parkinson's disease."
Dr. Brudek and his team looked at all 76,477 individuals diagnosed with IBD in Denmark in 1977-2014, comparing them to more than 7 million non-IBD controls matched by gender, age and vital status.
IBD patients were 22% more likely to develop PD during follow-up (hazard ratio, 1.22; 95% confidence interval, 1.09 to 1.35). The increased risk was similar for men and women.
Patients with ulcerative colitis were at higher risk of developing PD (HR, 1.35), but the risk was not significantly increased for those with Crohn's disease (HR, 1.12).
Age at IBD diagnosis was not associated with PD risk and the age at PD diagnosis was similar for those with and without IBD.
"Clinicians should be aware of early parkinsonian symptoms in IBD patients," Dr. Brudek said. "However, we want to highlight at this point that a limited number of IBD patients will develop Parkinson's disease."
In a joint email, Dr. Malu Tansey of Emory University in Atlanta, who studies neuroinflammation in PD, Alzheimer's and depression, and Madelyn Houser, a graduate student, said the "study provides further support for theories implicating inflammatory mechanisms in the pathogenesis of PD."
"It might have been predicted that individuals who have lived with IBD longer might have a greater risk of PD or earlier PD onset due to accumulated pathological effects of inflammation, but this does not appear to be the case according to this study," they added.
"This could suggest that the epidemiological connection is based on an underlying factor, like a shared genetic predisposition . . . or some kind of inherent immunological dysfunction, or that the aspect(s) of IBD that increase susceptibility to PD are not dependent on cumulative exposure."
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