title: Rate of cognitive decline during the premotor phase of essential tremor: a prospective study.
abstract: OBJECTIVE
  To characterize the rate of cognitive decline during the premotor phase of essential tremor (ET) in comparison to prevalent ET cases and controls.
  
  
  METHODS
  In this population-based, prospective study of people aged 65 years and older (Neurological Disorders in Central Spain), a 37-item version of the Mini-Mental State Examination was administered at 2 visits (baseline and follow-up, approximately 3 years later). We compared the rate of cognitive decline in 3 groups: prevalent ET cases (i.e., participants diagnosed with ET at baseline and at follow-up), "premotor" ET cases (i.e., participants diagnosed with incident ET at follow-up, but not at baseline), and controls (i.e., participants not diagnosed with ET at baseline or follow-up).
  
  
  RESULTS
  The 2,375 participants included 135 prevalent ET cases, 56 premotor ET cases, and 2,184 controls. During the follow-up period of 3.4 ± 0.5 years (mean ± SD), the 37-item version of the Mini-Mental State Examination declined by 0.7 ± 3.3 points (0.2 ± 1.0 points/year) in prevalent ET cases, 1.1 ± 3.5 points (0.3 ± 1.0 points/year) in premotor ET cases, and 0.1 ± 3.9 points (0.0 ± 1.2 points/year) in controls (p = 0.014). The difference between premotor ET cases and controls was significant (p = 0.046), as was the difference between prevalent ET cases and controls (p = 0.027).
  
  
  CONCLUSIONS
  In this prospective cohort, cognitive test scores in premotor and prevalent ET cases declined at a faster rate than in elders without this disease. A decline in global cognitive function may occur in a premotor phase of ET.
authors.affiliation: Department of Neurology, University Hospital 12 de Octubre, Madrid, Spain. jbenitol@meditex.es
authors.forename: Julián
authors.initials: J
authors.lastname: Benito-León
authors.forename: Elan D
authors.initials: ED
authors.lastname: Louis
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Sánchez-Ferro
authors.forename: Félix
authors.initials: F
authors.lastname: Bermejo-Pareja
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D020329:Essential Tremor / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D015995:Prevalence; D011446:Prospective Studies; D013030:Spain