"... the incidence of PD was 78% lower in patients with IBD who received anti-TNF therapy compared with those who did not ..."

"These findings support a role of systemic inflammation in the development of both PD and IBD ..."

Medscape article: Old Drug May Get New Life in Parkinson's Prevention.
Medscape: Medscape Access

EurekAlert article: Parkinson's disease among patients with inflammatory bowel disease.
Parkinson's disease among patients with inflammatory bowel disease | EurekAlert! Science News

Research paper (not open access, only "Key Points" and "Abstract" are accessible): Anti-Tumor Necrosis Factor Therapy and Incidence of Parkinson Disease Among Patients With Inflammatory Bowel Disease, Inga Peter et al., JAMA Neurol. Published online April 23, 2018. doi:10.1001/jamaneurol.2018.0605.
Anti–Tumor Necrosis Factor Therapy and Incidence of Parkinson Disease Among Patients With Inflammatory Bowel Disease | Gastroenterology | JAMA Neurology | JAMA Network

Editorial (not open access, only first page is accessible): Discovering New Benefits From Old Drugs With Big Data - Promise for Parkinson Disease, Abby Olsen et al., JAMA Neurol. Published online April 23, 2018. doi:10.1001/jamaneurol.2018.0345.
Discovering New Benefits From Old Drugs With Big Data—Promise for Parkinson Disease | Gastroenterology | JAMA Neurology | JAMA Network

Although the research paper and the editorial are not open access, I found the bits that were accessible to be of interest.