title: Variability of response time as a predictor of methylphenidate treatment response in korean children with attention deficit hyperactivity disorder.
abstract: OBJECTIVE
  Methylphenidate (MPH) is an effective medication for the treatment of attention deficit hyperactivity disorder (ADHD). However, about 30% of patients do not respond to or are unable to tolerate MPH. Based on previous findings, we hypothesized that great variability in response time (RT) among Korean children with ADHD on a computerized continuous performance attention test would be related to poor MPH treatment response.
  
  
  METHODS
  Children (ages 6-18 years) with ADHD were recruited for a prospective 12-week, open-labeled, multicenter study to examine optimal dosage of OROS methylphenidate. Of the 144 subjects selected, 28 dropped out due to adverse events, medication noncompliance, or follow-up loss, and an additional 26 subjects with comorbid disorders were excluded from statistical analyses. We defined 'responders' as subjects who received a score of less than 18 on the attention deficit hyperactivity disorder rating scale (ARS; Korean version, K-ARS) and a score of 1 or 2 on the Clinical Global Impression-Improvement scale (CGI-I). RT variability was assessed with the ADHD diagnostic system (ADS).
  
  
  RESULTS
  Fifty-nine (67%) subjects responded to MPH treatment. The non-responders showed greater RT variability at baseline (Mann Whitney U = 577.0, p < 0.01). Baseline RT variability was a significant predictor of MPH response (Nagelkerke R(2) = 0.136, p < 0.01). It predicted 94.9% of responder, 17.2% of non-responder and 69.3% of overall group.
  
  
  CONCLUSIONS
  High RT variability may predict poor response to MPH treatment in children with ADHD.
authors.affiliation: Department of Psychiatry, Sungkyunkwan University School of Medicine, Kangbuk Samsung Hospital, Seoul, Korea.
authors.forename: Seung-Hye
authors.initials: SH
authors.lastname: Lee
authors.forename: Dong-Ho
authors.initials: DH
authors.lastname: Song
authors.forename: Bung-Nyun
authors.initials: BN
authors.lastname: Kim
authors.forename: Yoo Sook
authors.initials: YS
authors.lastname: Joung
authors.forename: Eun Hye
authors.initials: EH
authors.lastname: Ha
authors.forename: Keun-Ah
authors.initials: KA
authors.lastname: Cheon
authors.forename: Yee-Jin
authors.initials: YJ
authors.lastname: Shin
authors.forename: Hee Jeong
authors.initials: HJ
authors.lastname: Yoo
authors.forename: Dong-Won
authors.initials: DW
authors.lastname: Shin
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy*; D002648:Child; D005260:Female; D006801:Humans; D007723:Korea; D008297:Male; D008774:Methylphenidate / Q000627:therapeutic use*; D011930:Reaction Time; D016896:Treatment Outcome
chemical_list: D008774:Methylphenidate