title: Familial aggregation of Parkinson's disease: a population-based case-control study in Europe. EUROPARKINSON Study Group.
abstract: OBJECTIVE
  To investigate the familial aggregation of PD in a large collaborative population-based case-control study.
  
  
  BACKGROUND
  Most previous case-control studies of the familial aggregation of PD have been hospital- or clinic-based.
  
  
  METHODS
  We included 219 prevalent cases ascertained in three European populations (centers), using a two-phase design consisting of screening and examination by a neurologist. Each case was matched by age, sex, and center to three controls drawn from the same populations (n = 657). Presence of PD among first-degree relatives (parents and siblings) was determined using the family history approach for 175 cases and 481 controls.
  
  
  RESULTS
  Overall, a positive family history (at least one parent or sibling affected by PD) was reported in 10.3% of patients and 3.5% of controls (odds ratio [OR] = 3.2; 95% confidence interval [CI] = 1.6 to 6.6). A similar association was observed when analyses were restricted to nondemented patients and controls (OR = 3.9; 95% CI = 1.7 to 8.7) or to newly diagnosed patients (OR = 3.3; 95% CI = 0.9 to 11.9). We found a significant trend of increasing risk with increasing number of affected relatives (p = 0.003). Analyses stratified by age showed a stronger association for younger PD patients (OR = 7.6; 95% CI = 1.5 to 38.9) than for older patients (OR = 2.5; 95% CI = 1.1 to 5.7).
  
  
  CONCLUSIONS
  In this large sample of prevalent PD patients and population-matched controls, PD significantly aggregates in families, with the strength of the association being age-dependent. Therefore, familial factors, which can be genetic, environmental, or both, play a role in PD.
authors.affiliation: INSERM U 360, Recherches Epidémiologiques en Neurologie et Psychopathologie, Hôpital de la Salpêtrière, Paris, France. elbaz@ccr.jussieu.fr
authors.forename: A
authors.initials: A
authors.lastname: Elbaz
authors.forename: F
authors.initials: F
authors.lastname: Grigoletto
authors.forename: M
authors.initials: M
authors.lastname: Baldereschi
authors.forename: M M
authors.initials: MM
authors.lastname: Breteler
authors.forename: J M
authors.initials: JM
authors.lastname: Manubens-Bertran
authors.forename: S
authors.initials: S
authors.lastname: Lopez-Pousa
authors.forename: J F
authors.initials: JF
authors.lastname: Dartigues
authors.forename: A
authors.initials: A
authors.lastname: Alpérovitch
authors.forename: C
authors.initials: C
authors.lastname: Tzourio
authors.forename: W A
authors.initials: WA
authors.lastname: Rocca
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005060:Europe / Q000453:epidemiology; D005828:Genetics, Population; D006801:Humans; D008875:Middle Aged; D010300:Parkinson Disease / Q000453:epidemiology* / Q000235:genetics*