title: Head injury and risk for Parkinson disease: results from a Danish case-control study.
abstract: OBJECTIVE
  To examine the association between head injuries throughout life and the risk for Parkinson disease (PD) in an interview-based case-control study.
  
  
  METHODS
  We identified 1,705 patients diagnosed with PD at 10 neurologic centers in Denmark in 1996-2009 and verified their diagnoses in medical records. Patients were matched to 1,785 controls randomly selected from the Danish Central Population Register on sex and year of birth. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression.
  
  
  RESULTS
  We observed no association between any head injury before first cardinal symptom and PD (OR 1.02; 95% CI 0.88, 1.19). Examination of number of head injuries (1: OR 1.02; 95% CI 0.87, 1.20; ≥2: OR 1.03; 95% CI 0.72, 1.47) or hospitalization for a head injury (OR 0.89; 95% CI 0.70, 1.12) did not show an association with PD. For 954 study subjects with at least one head injury, there was no evidence of an association between loss of consciousness (OR 0.89; 95% CI 0.67, 1.17), duration of loss of consciousness (≤1 minute: OR 0.93; 95% CI 0.58, 1.49; 1-5 minutes: OR 0.74; 95% CI 0.51, 1.08; ≥5 minutes: OR 0.81; 95% CI 0.53, 1.24), or amnesia (OR 1.31; 95% CI 0.88, 1.95) and risk for PD. Application of a lag time of 10 years between head injury and first cardinal symptom resulted in similar risk estimates.
  
  
  CONCLUSIONS
  The results do not support the hypothesis that head injury increases the risk for PD.
authors: From the Danish Cancer Society Research Center (L.K., K.R., L.R., J.C., C.F.L.), Danish Cancer Society, Copenhagen, Denmark; the Department of Epidemiology, Fielding School of Public Health (P.-C.L., B.R.), and the Department of Neurology, School of Medicine (B.R.), University of California, Los Angeles; the Department of Health Care Management (P.-C.L.), College of Healthcare Administration and Management, National Taipei University of Nursing Health Sciences, Taipei, Taiwan; and the Department of Occupational and Environmental Medicine (C.F.L.), Bispebjerg Hospital, Copenhagen, Denmark. kenborg@cancer.dk.
authors: Line
authors: L
authors: Kenborg
authors: From the Danish Cancer Society Research Center (L.K., K.R., L.R., J.C., C.F.L.), Danish Cancer Society, Copenhagen, Denmark; the Department of Epidemiology, Fielding School of Public Health (P.-C.L., B.R.), and the Department of Neurology, School of Medicine (B.R.), University of California, Los Angeles; the Department of Health Care Management (P.-C.L.), College of Healthcare Administration and Management, National Taipei University of Nursing Health Sciences, Taipei, Taiwan; and the Department of Occupational and Environmental Medicine (C.F.L.), Bispebjerg Hospital, Copenhagen, Denmark.
authors: Kathrine
authors: K
authors: Rugbjerg
authors: From the Danish Cancer Society Research Center (L.K., K.R., L.R., J.C., C.F.L.), Danish Cancer Society, Copenhagen, Denmark; the Department of Epidemiology, Fielding School of Public Health (P.-C.L., B.R.), and the Department of Neurology, School of Medicine (B.R.), University of California, Los Angeles; the Department of Health Care Management (P.-C.L.), College of Healthcare Administration and Management, National Taipei University of Nursing Health Sciences, Taipei, Taiwan; and the Department of Occupational and Environmental Medicine (C.F.L.), Bispebjerg Hospital, Copenhagen, Denmark.
authors: Pei-Chen
authors: PC
authors: Lee
authors: From the Danish Cancer Society Research Center (L.K., K.R., L.R., J.C., C.F.L.), Danish Cancer Society, Copenhagen, Denmark; the Department of Epidemiology, Fielding School of Public Health (P.-C.L., B.R.), and the Department of Neurology, School of Medicine (B.R.), University of California, Los Angeles; the Department of Health Care Management (P.-C.L.), College of Healthcare Administration and Management, National Taipei University of Nursing Health Sciences, Taipei, Taiwan; and the Department of Occupational and Environmental Medicine (C.F.L.), Bispebjerg Hospital, Copenhagen, Denmark.
authors: Line
authors: L
authors: Ravnskjær
authors: From the Danish Cancer Society Research Center (L.K., K.R., L.R., J.C., C.F.L.), Danish Cancer Society, Copenhagen, Denmark; the Department of Epidemiology, Fielding School of Public Health (P.-C.L., B.R.), and the Department of Neurology, School of Medicine (B.R.), University of California, Los Angeles; the Department of Health Care Management (P.-C.L.), College of Healthcare Administration and Management, National Taipei University of Nursing Health Sciences, Taipei, Taiwan; and the Department of Occupational and Environmental Medicine (C.F.L.), Bispebjerg Hospital, Copenhagen, Denmark.
authors: Jane
authors: J
authors: Christensen
authors: From the Danish Cancer Society Research Center (L.K., K.R., L.R., J.C., C.F.L.), Danish Cancer Society, Copenhagen, Denmark; the Department of Epidemiology, Fielding School of Public Health (P.-C.L., B.R.), and the Department of Neurology, School of Medicine (B.R.), University of California, Los Angeles; the Department of Health Care Management (P.-C.L.), College of Healthcare Administration and Management, National Taipei University of Nursing Health Sciences, Taipei, Taiwan; and the Department of Occupational and Environmental Medicine (C.F.L.), Bispebjerg Hospital, Copenhagen, Denmark.
authors: Beate
authors: B
authors: Ritz
authors: From the Danish Cancer Society Research Center (L.K., K.R., L.R., J.C., C.F.L.), Danish Cancer Society, Copenhagen, Denmark; the Department of Epidemiology, Fielding School of Public Health (P.-C.L., B.R.), and the Department of Neurology, School of Medicine (B.R.), University of California, Los Angeles; the Department of Health Care Management (P.-C.L.), College of Healthcare Administration and Management, National Taipei University of Nursing Health Sciences, Taipei, Taiwan; and the Department of Occupational and Environmental Medicine (C.F.L.), Bispebjerg Hospital, Copenhagen, Denmark.
authors: Christina F
authors: CF
authors: Lassen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D006259:Craniocerebral Trauma / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology*; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis* / Q000453:epidemiology* / Q000209:etiology; D012307:Risk Factors