Intended for healthcare professionals


Risk of Parkinson’s disease after hospital contact for head injury: population based case-control study

BMJ 2008; 337 doi: (Published 15 December 2008) Cite this as: BMJ 2008;337:a2494
  1. Kathrine Rugbjerg, research fellow1,
  2. Beate Ritz, professor2,
  3. Lise Korbo, chief3,
  4. Nick Martinussen, data manager1,
  5. Jørgen H Olsen, director1
  1. 1Institute of Cancer Epidemiology, Danish Cancer Society, 49 Strandboulevarden, DK-2100 Copenhagen, Denmark
  2. 2Department of Epidemiology and Environmental Health Sciences, School of Public Health, University of California at Los Angeles (UCLA), USA
  3. 3Department of Neurology, Bispebjerg Hospital, Copenhagen
  1. Correspondence to: K Rugbjerg rugbjerg{at}
  • Accepted 19 September 2008


Objective To determine whether a hospital contact for a head injury increases the risk of subsequently developing Parkinson’s disease.

Design Population based case-control study.

Setting Denmark.

Participants 13 695 patients with a primary diagnosis of Parkinson’s disease in the Danish national hospital register during 1986-2006, each matched on age and sex to five population controls selected at random from inhabitants in Denmark alive at the date of the patient’s diagnosis (n=68 445).

Main outcome measures Hospital contacts for head injuries ascertained from hospital register; frequency of history of head injury.

Results An overall 50% increase in prevalence of hospital contacts for head injury was seen before the first registration of Parkinson’s disease in this population (odds ratio 1.5, 95% confidence interval 1.4 to 1.7). The observed association was, however, due almost entirely to injuries that occurred during the three months before the first record of Parkinson’s disease (odds ratio 8.0, 5.6 to 11.6), and no association was found between the two events when they occurred 10 or more years apart (1.1, 0.9 to 1.3).

Conclusions The steeply increased frequency of hospital contacts for a head injury during the months preceding the date at which Parkinson’s disease was first recorded is a consequence of the evolving movement disorder rather than its cause.


  • Contributors: JHO and BR designed and planned the study and developed the protocol. KR and NM did the statistical analyses. KR and JHO interpreted the final data analyses and wrote the manuscript. All authors read and critically commented on the paper. KR is the guarantor.

  • Funding: This study was supported by grants from the National Institutes of Health, USA (grant No R01 ES013717) and the UCLA Udall Parkinson Disease Center of Excellence (grant No P50 NS038367). The funding source had no role in the design or analysis of the study or in the decision to submit the manuscript for publication.

  • Competing interests: None declared.

  • Ethical approval: The study protocol was approved by the Danish Data Protection Agency (No 2002-41-2112).

  • Provenance and peer review: Not commissioned; externally peer reviewed.

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

View Full Text