title: A cross-sectional study of the development of volitional control of spatial attention in children with chromosome 22q11.2 deletion syndrome.
abstract: BACKGROUND
  Chromosome 22q11.2 deletion syndrome (22q11.2DS) results from a 1.5- to 3-megabase deletion on the long arm of chromosome 22 and occurs in approximately 1 in 4000 live births. Previous studies indicate that children with 22q11.2DS are impaired on tasks involving spatial attention. However, the degree to which these impairments are due to volitionally generated (endogenous) or reflexive (exogenous) orienting of attention is unclear. Additionally, the efficacy of these component attention processes throughout child development in 22q11.2DS has yet to be examined.
  
  
  METHODS
  Here we compared the performance of a wide age range (7 to 14 years) of children with 22q11.2DS to typically developing (TD) children on a comprehensive visual cueing paradigm to dissociate the contributions of endogenous and exogenous attentional impairments. Paired and two-sample t-tests were used to compare outcome measures within a group or between groups. Additionally, repeated measures regression models were fit to the data in order to examine effects of age on performance.
  
  
  RESULTS
  We found that children with 22q11.2DS were impaired on a cueing task with an endogenous cue, but not on the same task with an exogenous cue. Additionally, it was younger children exclusively who were impaired on endogenous cueing when compared to age-matched TD children. Older children with 22q11.2DS performed comparably to age-matched TD peers on the endogenous cueing task.
  
  
  CONCLUSIONS
  These results suggest that endogenous but not exogenous orienting of attention is selectively impaired in children with 22q11.2DS. Additionally, the age effect on cueing in children with 22q11.2DS suggests a possible altered developmental trajectory of endogenous cueing.
authors.affiliation: MIND Institute and Department of Psychiatry and Behavioral Sciences, University of California, Davis, 2825 50th Street, Sacramento, CA 95817, USA. hmshapiro@ucdavis.edu.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Shapiro
authors.forename: Yukari
authors.initials: Y
authors.lastname: Takarae
authors.forename: Danielle J
authors.initials: DJ
authors.lastname: Harvey
authors.forename: Margarita H
authors.initials: MH
authors.lastname: Cabaral
authors.forename: Tony J
authors.initials: TJ
authors.lastname: Simon