"... 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.
EurekAlert article: Parkinson's disease among patients with inflammatory bowel disease.
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.
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.
Although the research paper and the editorial are not open access, I found the bits that were accessible to be of interest.