title: Tics and problem behaviors in schoolchildren: prevalence, characterization, and associations.
abstract: OBJECTIVE
  Tic disorders are the most common movement disorder diagnosed in children and have symptoms that fluctuate in frequency and intensity over time. We conducted an 8-month longitudinal observational study to determine the variations in frequency of motor tics and associated problem behaviors.
  
  
  METHODS
  A total of 553 children, kindergarten through sixth grade, were observed monthly from November 1999 to June 2000 by 3 raters. Motor tics were recorded by location and rated for severity as none (0), mild (1), moderate (2), or severe (3). Problem behaviors were rated as absent (0), subclinical (1), or clinical (2) in each of 6 categories: disruptive, hyperactive, impulsive, aggressive, anxious, and distracted.
  
  
  RESULTS
  The monthly point prevalence of motor tics ranged from 3.2% to 9.6%, with an overall frequency of 24.4%. The monthly point prevalence of problem behaviors ranged from 2.6% to 11.0%, with an overall frequency of 25.7%. The incidence of motor tics and problem behaviors was significantly higher during the winter months of November through February, compared with the spring months of March through June (motor tics: z = 4.97; problem behaviors: z = 3.79). Motor tics were observed in 2 distinct patterns (isolated and persistent), which varied by the number of months present, gender ratio of affected children, severity of tic symptoms, and association with problem behaviors.
  
  
  CONCLUSIONS
  Motor tics and problem behaviors are frequent occurrences among schoolchildren and seem to occur more frequently during the winter months. For most children, the tics were mild, observed on only 1 occasion, and were not accompanied by problem behaviors.
authors.affiliation: Pediatrics and Developmental Neuropsychiatry Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892-1255, USA. sniderl@intra.nimh.nih.gov
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Snider
authors.forename: Laura D
authors.initials: LD
authors.lastname: Seligman
authors.forename: Bethany R
authors.initials: BR
authors.lastname: Ketchen
authors.forename: Sara J
authors.initials: SJ
authors.lastname: Levitt
authors.forename: Lauren R
authors.initials: LR
authors.lastname: Bates
authors.forename: Marjorie A
authors.initials: MA
authors.lastname: Garvey
authors.forename: Susan E
authors.initials: SE
authors.lastname: Swedo
mesh_terms: D002648:Child; D002653:Child Behavior Disorders / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D015995:Prevalence; D013981:Tic Disorders / Q000453:epidemiology*