title: Reduced body mass index in essential tremor: a study of 382 cases and 392 matched controls.
abstract: OBJECTIVE
  There is mounting evidence that essential tremor (ET) is a neurodegenerative disease. Reduced body mass index (BMI) is a clinical feature of many neurodegenerative diseases, yet there has been little documentation of BMI in patients with ET.
  
  
  METHODS
  Essential tremor cases and controls were enrolled in a study of the environmental epidemiology of ET at Columbia University Medical Center. Weight and height were measured using a standard protocol; BMI was weight (kg) divided by height (m(2)). Daily calorie count (kcal) was calculated using the Willett Semi-Quantitative Food Frequency Questionnaire. Tremor severity was assessed with a clinical rating scale (total tremor score, range 0-36).
  
  
  RESULTS
  The 382 ET cases and 392 controls were similar with respect to age, gender and other demographic variables. BMI was lower in ET cases than controls [26.7 ± 5.0 (median = 26.2) vs. 27.7 ± 5.6 (median = 26.7), P = 0.03] despite the fact that the daily caloric intake was marginally higher in ET cases than controls (P = 0.09). In ET cases, BMI was not associated with tremor severity (Spearman's r = -0.02, P = 0.66) but, among younger onset ET cases, longer tremor duration was associated with lower BMI (Spearman's r = -0.14, P = 0.049).
  
  
  CONCLUSIONS
  The observed lower BMI in ET is consistent with the neurodegenerative hypothesis of ET. The data also suggest that some mechanism other than decreased daily caloric intake or an involuntary movement-related increased burning of calories is likely to account for this case-control difference.
authors.affiliation: GH Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
authors.forename: E D
authors.initials: ED
authors.lastname: Louis
authors.forename: M
authors.initials: M
authors.lastname: Michalec
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D001835:Body Weight; D020329:Essential Tremor / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged
keywords: body mass index; clinical; epidemiology; essential tremor; neurodegeneration