title: Intellectual development in Noonan syndrome: a longitudinal study.
abstract: Although cognitive impairments in adults with Noonan syndrome seem to be limited to a low-average intelligence and slower processing speed, studies in children with Noonan syndrome have demonstrated more extensive cognitive problems. These include deficits in language skills, memory, attention, and executive functioning. This longitudinal study is the first to investigate intellectual development in a group of individuals with Noonan syndrome.
  
  
  
  Sixteen patients with Noonan syndrome underwent intelligence assessment both in childhood and in adulthood, using Wechsler's intelligence scales. IQ scores and Wechsler standard scores achieved in childhood and adulthood were compared. Subsequently, verbal and performance IQ in childhood were used as predictors for adult IQ and index scores.
  
  
  
  Compared with childhood scores, adult full-scale IQ and performance IQ significantly increased. Adult performance IQ was higher than verbal IQ. Childhood performance IQ and verbal IQ together predicted all adult IQ and index scores, except for the processing speed index.
  
  
  
  Childhood IQ was a significant predictor of adult intelligence in patients with Noonan syndrome. Performance IQ advanced to a normal level in adulthood, while verbal IQ did not develop proportionately, resulting in a discrepancy between adult performance IQ and verbal IQ. This finding could suggest a delay in the development of executive functioning in patients with Noonan syndrome, which seems to be outgrown in adulthood.
authors.affiliation: Centre of Excellence for Neuropsychiatry Vincent van Gogh Institute for Psychiatry Venray The Netherlands; Centre of Excellence for Korsakoff and Alcohol-Related Cognitive Disorders Vincent van Gogh Institute for Psychiatry Venray The Netherlands; Donders Institute for Brain Cognition and Behavior Radboud University Nijmegen Nijmegen The Netherlands; Behavioral Science Institute Radboud University Nijmegen NijmegenThe Netherlands.
authors.forename: Renée L
authors.initials: RL
authors.lastname: Roelofs
authors.affiliation: School of Psychology and Artificial Intelligence Radboud University Nijmegen Nijmegen The Netherlands.
authors.forename: Nikki
authors.initials: N
authors.lastname: Janssen
authors.affiliation: Centre of Excellence for Neuropsychiatry Vincent van Gogh Institute for Psychiatry Venray The Netherlands; Donders Institute for Brain Cognition and Behavior Radboud University Nijmegen Nijmegen The Netherlands.
authors.forename: Ellen
authors.initials: E
authors.lastname: Wingbermühle
authors.affiliation: Centre of Excellence for Korsakoff and Alcohol-Related Cognitive Disorders Vincent van Gogh Institute for Psychiatry Venray The Netherlands; Donders Institute for Brain Cognition and Behavior Radboud University Nijmegen Nijmegen The Netherlands; Department of Medical Psychology Radboud University Medical Center Nijmegen The Netherlands.
authors.forename: Roy P C
authors.initials: RP
authors.lastname: Kessels
authors.affiliation: Centre of Excellence for Neuropsychiatry Vincent van Gogh Institute for Psychiatry Venray The Netherlands; Centre of Excellence for Korsakoff and Alcohol-Related Cognitive Disorders Vincent van Gogh Institute for Psychiatry Venray The Netherlands; Donders Institute for Brain Cognition and Behavior Radboud University Nijmegen Nijmegen The Netherlands; Behavioral Science Institute Radboud University Nijmegen NijmegenThe Netherlands.
authors.forename: Jos I M
authors.initials: JI
authors.lastname: Egger
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D007360:Intelligence / Q000502:physiology*; D007361:Intelligence Tests; D008137:Longitudinal Studies; D008297:Male; D009634:Noonan Syndrome / Q000503:physiopathology* / Q000523:psychology*
keywords: Cognition; Noonan syndrome; RAS‐MAPK; contextual neuropsychology; intelligence; longitudinal design; neurodevelopmental disorder