title: Head trauma preceding PD: a case-control study.
abstract: OBJECTIVE
  To investigate the association of PD with preceding head trauma using a case-control study design.
  
  
  METHODS
  The medical records-linkage system of the Rochester Epidemiology Project was used to identify 196 subjects who developed PD in Olmsted County, MN, from 1976 through 1995. Each incident case was matched by age (+/-1 year) and sex to a general population control. The complete medical records of cases and controls in the system were reviewed to detect preceding episodes of head trauma.
  
  
  RESULTS
  The frequency of head trauma overall was significantly higher in cases than in controls (odds ratio [OR] = 4.3; 95% CI = 1.2 to 15.2). Compared with subjects who never experienced a trauma, subjects who experienced a mild head trauma with only amnesia had no increased risk; however, subjects who experienced a mild head trauma with loss of consciousness or a more severe trauma had an OR of 11.0 (95% CI = 1.4 to 85.2). Although not significant, head trauma resulting in hospitalization was more frequent in cases than in control subjects (OR = 8.0; 95% CI = 1.0 to 64.0). Whereas the OR was higher for men than women and for patients with later onset of PD than for patients with earlier onset, these differences were not significant.
  
  
  CONCLUSIONS
  These results suggest an association between head trauma and the later development of PD that varies with severity. Although the OR is high (4.3), the population attributable risk is only 5% because head trauma is a relatively rare event.
authors.affiliation: Department of Neurology, Mayo Foundation, Rochester, MN 55905, USA. bower.james@mayo.edu
authors.forename: J H
authors.initials: JH
authors.lastname: Bower
authors.forename: D M
authors.initials: DM
authors.lastname: Maraganore
authors.forename: B J
authors.initials: BJ
authors.lastname: Peterson
authors.forename: S K
authors.initials: SK
authors.lastname: McDonnell
authors.forename: J E
authors.initials: JE
authors.lastname: Ahlskog
authors.forename: W A
authors.initials: WA
authors.lastname: Rocca
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000647:Amnesia / Q000209:etiology; D016022:Case-Control Studies; D006259:Craniocerebral Trauma / Q000150:complications / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008498:Medical Record Linkage; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D008959:Models, Neurological; D016017:Odds Ratio; D010300:Parkinson Disease / Q000453:epidemiology* / Q000209:etiology; D013997:Time Factors; D015599:Trauma Severity Indices