title: Digitized Spiral Drawing: A Possible Biomarker for Early Parkinson's Disease.
abstract: BACKGROUND
  Pre-clinical markers of Parkinson's Disease (PD) are needed, and to be relevant in pre-clinical disease, they should be quantifiably abnormal in early disease as well. Handwriting is impaired early in PD and can be evaluated using computerized analysis of drawn spirals, capturing kinematic, dynamic, and spatial abnormalities and calculating indices that quantify motor performance and disability. Digitized spiral drawing correlates with motor scores and may be more sensitive in detecting early changes than subjective ratings. However, whether changes in spiral drawing are abnormal compared with controls and whether changes are detected in early PD are unknown.
  
  
  METHODS
  138 PD subjects (50 with early PD) and 150 controls drew spirals on a digitizing tablet, generating x, y, z (pressure) data-coordinates and time. Derived indices corresponded to overall spiral execution (severity), shape and kinematic irregularity (second order smoothness, first order zero-crossing), tightness, mean speed and variability of spiral width. Linear mixed effect adjusted models comparing these indices and cross-validation were performed. Receiver operating characteristic analysis was applied to examine discriminative validity of combined indices.
  
  
  RESULTS
  All indices were significantly different between PD cases and controls, except for zero-crossing. A model using all indices had high discriminative validity (sensitivity = 0.86, specificity = 0.81). Discriminative validity was maintained in patients with early PD.
  
  
  CONCLUSIONS
  Spiral analysis accurately discriminates subjects with PD and early PD from controls supporting a role as a promising quantitative biomarker. Further assessment is needed to determine whether spiral changes are PD specific compared with other disorders and if present in pre-clinical PD.
authors.affiliation: Department of Neurology, Mount Sinai Beth Israel Medical Center, New York, New York, United States of America.|Department of Neurology, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Marta
authors.initials: M
authors.lastname: San Luciano
authors.affiliation: Department of Epidemiology and Population Health, Albert Einstein College of Medicine Bronx, New York, New York, United States of America.
authors.forename: Cuiling
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Neurology, Mount Sinai Beth Israel Medical Center, New York, New York, United States of America.
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Ortega
authors.affiliation: Department of Neurology, Columbia University, New York, New York, United States of America.
authors.forename: Qiping
authors.initials: Q
authors.lastname: Yu
authors.affiliation: Department of Neurology, Columbia University, New York, New York, United States of America.
authors.forename: Sarah
authors.initials: S
authors.lastname: Boschung
authors.affiliation: Department of Neurology, Mount Sinai Beth Israel Medical Center, New York, New York, United States of America.
authors.forename: Jeannie
authors.initials: J
authors.lastname: Soto-Valencia
authors.affiliation: Department of Neurology, Mount Sinai Beth Israel Medical Center, New York, New York, United States of America.|Department of Neurology, Albert Einstein College of Medicine Bronx, New York, New York, United States of America.|Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America.
authors.forename: Susan B
authors.initials: SB
authors.lastname: Bressman
authors.affiliation: Department of Neurology, Albert Einstein College of Medicine Bronx, New York, New York, United States of America.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Lipton
authors.affiliation: Department of Neurology, Columbia University, New York, New York, United States of America.
authors.forename: Seth
authors.initials: S
authors.lastname: Pullman
authors.affiliation: Department of Neurology, Mount Sinai Beth Israel Medical Center, New York, New York, United States of America.|Department of Neurology, Albert Einstein College of Medicine Bronx, New York, New York, United States of America.|Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America.
authors.forename: Rachel
authors.initials: R
authors.lastname: Saunders-Pullman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D015415:Biomarkers / Q000032:analysis*; D016022:Case-Control Studies; D016002:Discriminant Analysis; D005260:Female; D006236:Handwriting; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis*; D012372:ROC Curve
chemical_list: D015415:Biomarkers