title: Developmental trajectories of hierarchical visuo-spatial processing in fragile X syndrome and ASD: Within- and cross-syndrome variability.
abstract: OBJECTIVE
  Despite the advances in understanding visuo-spatial processing in developmental disorders such as ASD and fragile X syndrome (FXS), less is known about the profile of those with a comorbid diagnosis, or the role of within-disorder disparities between individuals across the ASD spectrum.
  
  
  METHODS
  Using a developmental trajectory approach, we tested 5 groups of children: Typically developing, FXS, FXS+ASD, ASD individuals who had low-moderate symptoms (HFA) and ASD individuals who had severe symptoms (LFA). Symptoms of ASD were assessed using the Childhood Autism Rating Scale: CARS and hierarchical visuo-spatial processing was assessed using the Navon task.
  
  
  RESULTS
  Crucially, results differed between HFA and LFA participants. Furthermore, the pattern of results differed between those who had a diagnosis of FXS only and FXS+ASD. Poorer performance within the FXS groups and the group who are low functioning on the ASD spectrum indicated a delayed developmental rate compared to typical controls.
  
  
  CONCLUSIONS
  This study showed that diagnosis and severity of symptoms are indicative of differences in visuo-spatial processing styles. It is important that heterogeneity within FXS and ASD populations are considered in subsequent studies and look beyond diagnostic group differences.
authors.affiliation: Division of Psychology, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK. Electronic address: carrie.ballantyne@uws.ac.uk.
authors.forename: Carrie J
authors.initials: CJ
authors.lastname: Ballantyne
authors.affiliation: Division of Psychology, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK. Electronic address: maria.nunez@kcl.ac.uk.
authors.forename: María
authors.initials: M
authors.lastname: Núñez
mesh_terms: D000293:Adolescent; D000067877:Autism Spectrum Disorder / Q000503:physiopathology / Q000523:psychology*; D016022:Case-Control Studies; D002648:Child; D002657:Child Development; D015331:Cohort Studies; D005260:Female; D005600:Fragile X Syndrome / Q000503:physiopathology / Q000523:psychology*; D006801:Humans; D008297:Male; D065855:Spatial Processing
keywords: Autism; Developmental trajectories; Fragile X syndrome; Hierarchical visuo-spatial processing