title: Association between urine cotinine levels, continuous performance test variables, and attention deficit hyperactivity disorder and learning disability symptoms in school-aged children.
abstract: BACKGROUND
  We examined the cross-sectional relationship between environmental tobacco smoke exposure, continuous performance test (CPT) measures, and attention deficit hyperactivity disorder (ADHD) or learning disability symptoms in school-aged children.
  
  
  METHODS
  In total, 989 children (526 boys, mean age 9.1 ± 0.7 years), recruited from five South Korean cities participated in this study. We used urine cotinine as a biomarker for environmental tobacco smoke exposure, and obtained the children's scores on a CPT. Parents completed the Korean versions of the ADHD rating scale-IV (ADHD-RS) and learning disability evaluation scale (LDES). Using generalized linear mixed model (GLMM), we assessed the associations between urine cotinine concentrations, neuropsychological variables, and symptoms of ADHD and learning disabilities. Additionally, we conducted structural equation models to explore the effects' pathways.
  
  
  RESULTS
  After adjusting for a range of relevant covariates, GLMM showed urinary cotinine levels were significantly and positively associated with CPT scores on omission errors, commission errors, response time, and response time variability, and with parent- and teacher-rated ADHD-RS scores. In addition, urine cotinine levels were negatively associated with LDES scores on spelling and mathematical calculations. The structural equation model revealed that CPT variables mediated the association between urine cotinine levels and parental reports of symptoms of ADHD and learning disabilities.
  
  
  CONCLUSIONS
  Our data indicate that environmental exposure to tobacco smoke is associated with ADHD and learning disabilities in children, and that impairments in attention and inhibitory control probably mediate the effect.
authors.affiliation: Division of Child and Adolescent Psychiatry, Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: S C
authors.initials: SC
authors.lastname: Cho
authors.forename: Y C
authors.initials: YC
authors.lastname: Hong
authors.forename: J W
authors.initials: JW
authors.lastname: Kim
authors.forename: S
authors.initials: S
authors.lastname: Park
authors.forename: M H
authors.initials: MH
authors.lastname: Park
authors.forename: J
authors.initials: J
authors.lastname: Hur
authors.forename: E J
authors.initials: EJ
authors.lastname: Park
authors.forename: S B
authors.initials: SB
authors.lastname: Hong
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.forename: M S
authors.initials: MS
authors.lastname: Shin
authors.forename: B N
authors.initials: BN
authors.lastname: Kim
authors.forename: H J
authors.initials: HJ
authors.lastname: Yoo
authors.forename: I H
authors.initials: IH
authors.lastname: Cho
authors.forename: S Y
authors.initials: SY
authors.lastname: Bhang
authors.forename: S
authors.initials: S
authors.lastname: Hahn
authors.forename: S K
authors.initials: SK
authors.lastname: Han
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000503:physiopathology* / Q000652:urine; D002648:Child; D003367:Cotinine / Q000652:urine*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D007859:Learning Disabilities / Q000503:physiopathology* / Q000652:urine; D008297:Male; D008960:Models, Psychological; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D056910:Republic of Korea; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution; D003367:Cotinine