This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.
ABSTRACT
Objectives: Traumatic brain injury (TBI) increased risk of Parkinson disease (PD) in many but not all epidemiologic studies, giving rise to speculations about modifying factors. A recent animal study suggested that the combination of TBI with subthreshold paraquat exposure increases dopaminergic neurodegeneration. The objective of our study was to investigate PD risk due to both TBI and paraquat exposure in humans.
Methods: From 2001 to 2011, we enrolled 357 incident idiopathic PD cases and 754 population controls in central California. Study participants were asked to report all head injuries with loss of consciousness for >5 minutes. Paraquat exposure was assessed via a validated geographic information system (GIS) based on records of pesticide applications to agricultural crops in California since 1974. This GIS tool assesses ambient pesticide exposure within 500 m of residences and workplaces.
Results: In logistic regression analyses, we observed a 2-fold increase in risk of PD for subjects who reported a TBI (adjusted odds ratio [AOR] 2.00, 95% confidence interval [CI] 1.28–3.14) and a weaker association for paraquat exposures (AOR 1.36, 95% CI 1.02–1.81). However, the risk of developing PD was 3-fold higher (AOR 3.01, 95% CI 1.51–6.01) in study participants with a TBI and exposure to paraquat than those exposed to neither risk factor.
Conclusions: While TBI and paraquat exposure each increase the risk of PD moderately, exposure to both factors almost tripled PD risk. These environmental factors seem to act together to increase PD risk in a more than additive manner.
Glossary
- AOR=
- adjusted odds ratio;
- CI=
- confidence interval;
- GIS=
- geographic information system;
- OR=
- odds ratio;
- PD=
- Parkinson disease;
- RERI=
- relative excess risk due to interaction;
- RR=
- relative risk;
- TBI=
- traumatic brain injury
Footnotes
Study funding: This work was supported by the National Institute of Environmental Health Science (grant numbers R01ES010544 and U54ES012078) and the National Institute of Neurological Disorders and Stroke (grant number P50NS038367); in addition, initial pilot funding was provided from NIH P30ES007048 and a pilot grant by the American Parkinson Disease Association.
Go to Neurology.org for full disclosures. Disclosures deemed relevant by the authors, if any, are provided at the end of this article.
- Received April 22, 2012.
- Accepted July 26, 2012.
- © 2012 American Academy of Neurology
AAN Members
We have changed the login procedure to improve access between AAN.com and the Neurology journals. If you are experiencing issues, please log out of AAN.com and clear history and cookies. (For instructions by browser, please click the instruction pages below). After clearing, choose preferred Journal and select login for AAN Members. You will be redirected to a login page where you can log in with your AAN ID number and password. When you are returned to the Journal, your name should appear at the top right of the page.
AAN Non-Member Subscribers
Purchase access
Letters: Rapid online correspondence
REQUIREMENTS
You must ensure that your Disclosures have been updated within the previous six months. Please go to our Submission Site to add or update your Disclosure information.
Your co-authors must send a completed Publishing Agreement Form to Neurology Staff (not necessary for the lead/corresponding author as the form below will suffice) before you upload your comment.
If you are responding to a comment that was written about an article you originally authored:
You (and co-authors) do not need to fill out forms or check disclosures as author forms are still valid
and apply to letter.
Submission specifications:
- Submissions must be < 200 words with < 5 references. Reference 1 must be the article on which you are commenting.
- Submissions should not have more than 5 authors. (Exception: original author replies can include all original authors of the article)
- Submit only on articles published within 6 months of issue date.
- Do not be redundant. Read any comments already posted on the article prior to submission.
- Submitted comments are subject to editing and editor review prior to posting.
You May Also be Interested in
Hastening the Diagnosis of Amyotrophic Lateral Sclerosis
Dr. Brian Callaghan and Dr. Kellen Quigg
► Watch
Topics Discussed
Alert Me
Recommended articles
Mild TBI and risk of Parkinson disease
Aldehyde dehydrogenase variation enhances effect of pesticides associated with Parkinson disease
The risk of Parkinson's disease with exposure to pesticides, farming, well water, and rural living
Traumatic brain injury preceding clinically diagnosed α-synucleinopathies