title: Elucidating X chromosome influences on Attention Deficit Hyperactivity Disorder and executive function.
abstract: OBJECTIVE
  To identify distinct behavioral and cognitive profiles associated with ADHD in Turner syndrome (TS), relative to idiopathic ADHD and neurotypical controls, in order to elucidate X-linked influences contributing to ADHD.
  
  
  METHODS
  We used a multilevel-model approach to compare 49 girls with TS to 37 neurotypical females, aged 5-12, on established measures of behavior (BASC-2) and neurocognitive function (NEPSY). We further compared girls with TS to BASC-2 and NEPSY age-matched reference data obtained from children with idiopathic ADHD.
  
  
  RESULTS
  Within the TS group, 51% scored at or above the "at-risk" range for ADHD-associated behaviors on the BASC-2 (TS/+ADHD). The BASC-2 behavioral profile in this TS/+ADHD-subgroup was comparable to a reference group of boys with ADHD with respect to attentional problems and hyperactivity. However, the TS/+ADHD-subgroup had significantly higher hyperactivity scores relative to a reference sample of girls with ADHD (p = 0.016). The behavioral profile in TS was associated with significantly lower attention and executive function scores on the NEPSY relative to neurotypical controls (p = 0.015); but was comparable to scores from a reference sample of children with idiopathic ADHD. Deficits in attention and executive function were not observed in girls with TS having low levels of ADHD-associated behavior (TS/-ADHD).
  
  
  CONCLUSIONS
  ADHD-associated behavioral and cognitive problems in TS are prevalent and comparable in severity to those found in children with idiopathic ADHD. The ADHD phenotype in TS also appears relatively independent of cognitive features typically associated with TS, like visuospatial weaknesses. These findings suggest that X-linked haploinsufficiency and downstream biological effects contribute to increased risk for ADHD.
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford, CA 94305, USA; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel. Electronic address: tgreen2@stanford.edu.
authors.forename: Tamar
authors.initials: T
authors.lastname: Green
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford, CA 94305, USA.
authors.forename: Sharon
authors.initials: S
authors.lastname: Bade Shrestha
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford, CA 94305, USA.
authors.forename: Lindsay C
authors.initials: LC
authors.lastname: Chromik
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford, CA 94305, USA.
authors.forename: Keetan
authors.initials: K
authors.lastname: Rutledge
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford, CA 94305, USA; University of Denver, Department of Psychology, Denver, CO 80210, USA.
authors.forename: Bruce F
authors.initials: BF
authors.lastname: Pennington
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford, CA 94305, USA; Department of Psychiatry and Behavioral Sciences, Stanford, CA 94305, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Hong
authors.affiliation: Center for Interdisciplinary Brain Sciences Research, Stanford, CA 94305, USA; Department of Psychiatry and Behavioral Sciences, Stanford, CA 94305, USA; Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Allan L
authors.initials: AL
authors.lastname: Reiss
mesh_terms: D001289:Attention Deficit Disorder with Hyperactivity / Q000209:etiology / Q000235:genetics / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D041321:Chromosomes, Human, X; D003072:Cognition Disorders / Q000209:etiology / Q000235:genetics / Q000503:physiopathology*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D010641:Phenotype; D012737:Sex Factors; D014424:Turner Syndrome / Q000150:complications / Q000235:genetics / Q000503:physiopathology*
keywords: Attention; Executive function; Hyperactivity; Idiopathic ADHD; Sex differences; Turner syndrome