title: Early- and late-onset essential tremor patients represent clinically distinct subgroups.
abstract: Essential tremor is a very common disease defined by sparse clinical criteria. It is unlikely that essential tremor is an etiologically homogeneous disease. Stratifying broadly defined diseases using clinical characteristics has often aided the etiopathological understanding. Most studies of essential tremor show 2 distinct age at onset peaks: early and late. This study investigates phenotypical differences between early- and late-onset essential tremor patients.
  
  
  
  We studied a sample of 1137 tremor patients. Of these patients, 978 suffered from definite or probable essential tremor. All of the patients underwent the same standardized examination encompassing, among other items, drawing of the Archimedes spiral and assessment of the Fahn-Tolosa-Marin scale.
  
  
  
  Two subgroups of early-onset (≤ 24 years of age, n = 317) and late-onset (≥ 46 years of age, n = 356) patients were selected based on the visual and mathematical analysis of the age-at-onset distribution. Tremor severity in both groups was comparable. Tremor progression measured as Archimedes spiral score and the Fahn-Tolosa-Marin subscales divided by the disease duration in 10-year bins was significantly faster in late-onset patients when compared with early-onset patients. Early-onset patients more frequently reported a positive family history and alcohol sensitivity of the tremor.
  
  
  
  The age-at-onset distribution suggests a distinction between early- and late-onset tremor. Early-onset and late-onset essential tremor differ in the progression rates and the frequencies of a positive family history and history of a positive effect of alcohol on tremor. © 2016 International Parkinson and Movement Disorder Society.
authors.affiliation: Department of Neurology, University Hospital Schleswig Holstein, Kiel, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Hopfner
authors.affiliation: Department of Neurology, University Hospital Schleswig Holstein, Kiel, Germany.
authors.forename: Anjuli
authors.initials: A
authors.lastname: Ahlf
authors.affiliation: Department of Neurology, University Hospital Schleswig Holstein, Kiel, Germany.
authors.forename: Delia
authors.initials: D
authors.lastname: Lorenz
authors.affiliation: Department of Neurology, University Hospital of Freiburg, Freiburg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Klebe
authors.affiliation: Department of Neurology, University Hospital Schleswig Holstein, Kiel, Germany.
authors.forename: Kirsten E
authors.initials: KE
authors.lastname: Zeuner
authors.affiliation: Department of Neurology, University Hospital Schleswig Holstein, Kiel, Germany.
authors.forename: Gregor
authors.initials: G
authors.lastname: Kuhlenbäumer
authors.affiliation: Department of Neurology, University Hospital Schleswig Holstein, Kiel, Germany. g.deuschl@neurologie.uni-kiel.de.
authors.forename: Günther
authors.initials: G
authors.lastname: Deuschl
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D018450:Disease Progression; D020329:Essential Tremor / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
keywords: Essential tremor; alcohol-response; classification; family history; progression; subgroups