RT Journal Article
SR Electronic
T1 The causal direction in the association between Parkinson’s disease and cigarette or nicotine use
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 161240
DO 10.1101/161240
A1 Nikodem Grzesiak
YR 2017
UL http://biorxiv.org/content/early/2017/07/10/161240.abstract
AB The association between cigarette use and Parkinson’s disease (PD) has been well known in the literature since more than 50 years ago. Large population studies showed that smokers developed PD less often than non-smokers and that the duration of smoking was inversely proportional to PD risk. There are two primary hypotheses for this association in the literature. First, long-standing hypothesis, is that smoking cigarettes is neuroprotective. The second, recent hypothesis, is that there exists biological predisposition to PD, which also manifests in decreased stimulus seeking behavior, hence lesser likelihood to smoke or use nicotine (reverse causation). The objective of this article is to summarize the evidence available in the literature and evaluate the causality of the association between Parkinson’s disease and smoking cigarettes or nicotine ingestion. It is found that the first, directly causal hypothesis is a stronger contributor to the effect, although the reversely causal mechanism could play a role. It is found that smokeless tobacco use decreases the risk of PD stronger than smoking cigarettes does, suggesting that nicotine is more important in neuroprotection than other cigarette smoke constituents.