title: Asperger syndrome in males over two decades: stability and predictors of diagnosis.
abstract: OBJECTIVE
  To examine the diagnostic stability of a childhood diagnosis of Asperger Syndrome (AS) into adulthood in a prospective longitudinal study, and identify the predictors of stability.
  
  
  METHODS
  One hundred males with AS diagnosed in childhood (T0) according to Gillberg's AS criteria, were followed up prospectively into adulthood over an average of 19 years (range 13-26 years). Fifty males (mean age 30 years) participated in this second follow-up (T2) of the cohort. Seventy-six had participated in a previous follow-up (T1) at mean age 22 years (47 participated in both follow-ups). Diagnosis at T2 was assessed using three sets of diagnostic criteria (Gillberg's AS criteria, DSM-IV Pervasive Developmental Disorder (PDD) and DSM-5 Autism Spectrum Disorder (ASD) criteria) and compared to previous assessments. Background predictors of diagnostic stability were analyzed. General functioning at T2 was assessed and compared to T1.
  
  
  RESULTS
  There was a decline in the stability of AS diagnosis over time, the rate dropping from 82% at T1 to 44% at T2, when using the Gillberg criteria. There was also a significant decrease in the rate of cases fulfilling any PDD diagnosis according to the DSM-IV, from 91% at T1 to 76% at T2 in the 47 cases followed up twice. Severity of autism spectrum symptoms at T1 was the main predictor of diagnostic stability at T2. Twenty percent of those meeting criteria for a PDD diagnosis according to DSM-IV, did not meet DSM-5 ASD criteria although they had marked difficulties in everyday life.
  
  
  CONCLUSIONS
  Asperger Syndrome, when considered as an ASD/PDD diagnosis, was fairly stable into adulthood, but there was a significant increase over time in cases no longer meeting criteria for an ASD diagnosis according to the DSM-IV, or AS according to the Gillberg criteria. Cases with a stable diagnosis showed significantly more core ASD symptoms in adolescence/young adulthood.
authors.affiliation: Gillberg Neuropsychiatry Centre, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden.
authors.forename: Adam
authors.initials: A
authors.lastname: Helles
authors.affiliation: Gillberg Neuropsychiatry Centre, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden.
authors.forename: Carina I
authors.initials: CI
authors.lastname: Gillberg
authors.affiliation: Gillberg Neuropsychiatry Centre, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden.
authors.forename: Christopher
authors.initials: C
authors.lastname: Gillberg
authors.affiliation: Gillberg Neuropsychiatry Centre, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Billstedt
mesh_terms: D000293:Adolescent; D000328:Adult; D020817:Asperger Syndrome / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology*; D002648:Child; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D055815:Young Adult
keywords: Asperger syndrome; autism spectrum disorder; diagnostic stability; longitudinal study; males; pervasive developmental disorder