title: Impaired prefrontal hemodynamic maturation in autism and unaffected siblings.
abstract: BACKGROUND
  Dysfunctions of the prefrontal cortex have been previously reported in individuals with autism spectrum disorders (ASD). Previous studies reported that first-degree relatives of individuals with ASD show atypical brain activity during tasks associated with social function. However, developmental changes in prefrontal dysfunction in ASD and genetic influences on the phenomena remain unclear. In the present study, we investigated the change in hemoglobin concentration in the prefrontal cortex as measured with near-infrared spectroscopy, in children and adults with ASD during the letter fluency test. Moreover, to clarify the genetic influences on developmental changes in the prefrontal dysfunction in ASD, unaffected siblings of the ASD participants were also assessed.
  
  
  RESULTS
  Study participants included 27 individuals with high-functioning ASD, age- and IQ-matched 24 healthy non-affected siblings, and 27 unrelated healthy controls aged 5 to 39 years. The relative concentration of hemoglobin ([Hb]) in the prefrontal cortex was measured during the letter fluency task. For children, neither the [oxy-Hb] change during the task nor task performances differed significantly among three groups. For adults, the [oxy-Hb] increases during the task were significantly smaller in the bilateral prefrontal cortex in ASD than those in control subjects, although task performances were similar. In the adult siblings the [oxy-Hb] change was intermediate between those in controls and ASDs.
  
  
  CONCLUSIONS
  Although indirectly due to a cross-sectional design, the results of this study indicate altered age-related change of prefrontal activity during executive processing in ASD. This is a first near-infrared spectroscopy study that implies alteration in the age-related changes of prefrontal activity in ASD and genetic influences on the phenomena.
authors.affiliation: Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo, Tokyo, Japan. yukik-tky@umin.ac.jp
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kawakubo
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kuwabara
authors.forename: Kei-Ichiro
authors.initials: K
authors.lastname: Watanabe
authors.forename: Michiko
authors.initials: M
authors.lastname: Minowa
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Someya
authors.forename: Iwao
authors.initials: I
authors.lastname: Minowa
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kono
authors.forename: Hisami
authors.initials: H
authors.lastname: Nishida
authors.forename: Toshiro
authors.initials: T
authors.lastname: Sugiyama
authors.forename: Nobumasa
authors.initials: N
authors.lastname: Kato
authors.forename: Kiyoto
authors.initials: K
authors.lastname: Kasai
mesh_terms: D000293:Adolescent; D000328:Adult; D001321:Autistic Disorder / Q000235:genetics* / Q000503:physiopathology*; D001931:Brain Mapping; D002648:Child; D002675:Child, Preschool; D005192:Family Health; D005260:Female; D020022:Genetic Predisposition to Disease; D006439:Hemodynamics; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007802:Language; D008297:Male; D010108:Oxyhemoglobins / Q000378:metabolism; D019265:Spectroscopy, Near-Infrared; D014705:Verbal Behavior
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins