title: Cognitive, language and social-cognitive skills of individuals with fragile X syndrome with and without autism.
abstract: BACKGROUND
  It is not known whether those with co-morbid fragile X syndrome (FXS) and autism represent a distinct subtype of FXS; whether the especially severe cognitive delays seen in studies of young children with co-morbid FXS and autism compared with those with only FXS continue into adolescence and young adulthood; and whether autism in those with FXS is 'true autism', i.e. reflects the same underlying problems as idiopathic autism.
  
  
  METHODS
  We compared the non-verbal IQ of adolescents and young adults with co-morbid FXS and autism (n = 10) with those with only FXS (n = 44). We then created a subsample of those with FXS only, matched on non-verbal IQ, mental age and gender (n = 21) to the subsample of those with co-morbid FXS and autism. We compared the two groups on measures of expressive language, receptive language (lexical, grammatical morphology and syntactic patterns), and a theory of mind task.
  
  
  RESULTS
  Those with co-morbid FXS and autism had lower non-verbal IQs than those with only FXS. The participants with co-morbid FXS and autism did not perform as well as the cognitive ability- and gender-matched participants with only FXS on the three measures of receptive language or the theory of mind task; there were no differences on the expressive language measure.
  
  
  CONCLUSIONS
  Our findings support the notion that those with co-morbid FXS and autism represent a distinct subtype of FXS, with more impairment in receptive language and theory of mind even when controlling for their lower non-verbal IQ relative to those with only FXS. The greater cognitive impairments observed in those with co-morbid FXS and autism continues into adolescence and young adulthood; and the autism seen in those with FXS appears to be the same as idiopathic autism.
authors.affiliation: Waisman Center University of Wisconsin, Madison, WI 53705, USA. lewis@waisman.wisc.edu
authors.forename: P
authors.initials: P
authors.lastname: Lewis
authors.forename: L
authors.initials: L
authors.lastname: Abbeduto
authors.forename: M
authors.initials: M
authors.lastname: Murphy
authors.forename: E
authors.initials: E
authors.lastname: Richmond
authors.forename: N
authors.initials: N
authors.lastname: Giles
authors.forename: L
authors.initials: L
authors.lastname: Bruno
authors.forename: S
authors.initials: S
authors.lastname: Schroeder
mesh_terms: D000293:Adolescent; D000328:Adult; D001321:Autistic Disorder / Q000175:diagnosis* / Q000523:psychology; D002648:Child; D003072:Cognition Disorders / Q000175:diagnosis* / Q000523:psychology; D015897:Comorbidity; D005260:Female; D005600:Fragile X Syndrome / Q000175:diagnosis* / Q000523:psychology*; D006801:Humans; D007360:Intelligence; D007805:Language Development Disorders / Q000175:diagnosis* / Q000523:psychology; D008297:Male; D018187:Personal Construct Theory; D010552:Personality Assessment / Q000706:statistics & numerical data; D011594:Psychometrics; D012016:Reference Values; D012920:Social Behavior Disorders / Q000175:diagnosis* / Q000523:psychology