This study came out towards the end of last year. Given the current interest in the DSM-5 diagnostic criteria and how they may impact the numbers of individuals diagnosed with PDD-NOS and Asperger syndrome, this seems timely.
The author list and the abstract are below. I’ll pull the conclusion from the abstract out for now:
Clinical distinctions among categorical diagnostic subtypes of autism spectrum disorders were not reliable even across sites with well-documented fidelity using standardized diagnostic instruments. Results support the move from existing subgroupings of autism spectrum disorders to dimensional descriptions of core features of social affect and fixated, repetitive behaviors, together with characteristics such as language level and cognitive function
To put it simply (and with less precision, but let’s go with this): Whether one is diagnosed as Asperger, PDD-NOS or Autistic Disorder is more dependent on where one is diagnosed than what one’s scores are on the tests given.
Seems likely this is part of the reason why there’s a move to incorporate all ASD’s under a single label.
The “lines” between autistic disorder, PDD-NOS and Asperger syndrome are blurred to say the least.
Here is the full author list:
Lord C, Petkova E, Hus V, Gan W, Lu F, Martin DM, Ousley O, Guy L, Bernier R, Gerdts J, Algermissen M, Whitaker A, Sutcliffe JS, Warren Z, Klin A, Saulnier C, Hanson E, Hundley R, Piggot J, Fombonne E, Steiman M, Miles J, Kanne SM, Goin-Kochel RP, Peters SU, Cook EH, Guter S, Tjernagel J, Green-Snyder LA, Bishop S, Esler A, Gotham K, Luyster R, Miller F, Olson J, Richler J, Risi S.
Weill Cornell Medical College, White Plains (Dr Lord), Nathan Klein Institute for Psychiatric Research, Orangeburg (Dr Petkova), and Department of Child and Adolescent Psychiatry, New York University (Drs Petkova and Gan and Ms Lu), Division of Child and Adolescent Psychiatry, Columbia University Medical Center (Drs Algermissen and Whitaker), and Simons Foundation (Ms Tjernagel), New York, New York; Autism and Communication Disorders Center (Drs Green-Snyder, Gotham, Miller, Olson, and Risi and Ms Hus) and Departments of Pediatrics and Human Genetics (Dr Martin), University of Michigan; Ann Arbor; Emory University School of Medicine (Drs Ousley, Klin, and Saulnier), and Marcus Autism Center, Children’s Healthcare of Atlanta (Dr Klin), Georgia; Center for Autism Research, Children’s Hospital of Philadelphia, Pennsylvania (Dr Guy); Departments of Psychiatry (Dr Bernier) and Psychology (Dr Gerdts), University of Washington, Seattle; Departments of Molecular Physiology and Biophysics and Psychiatry, Vanderbilt Kennedy Center (Dr Sutcliffe), and Departments of Pediatrics (Drs Warren and Peters) and Psychiatry (Dr Warren), Vanderbilt University Medical Center, Nashville, Tennessee; Division of Developmental Medicine, Children’s Hospital Boston, Harvard Medical School, Massachusetts (Drs Hanson, Hundley, and Luyster); Center for Autism Research and Treatment and Department of Psychiatry, Semel Institute of Neuroscience, University of California Los Angeles (Dr Piggot); Department of Psychiatry, Montreal Children’s Hospital, Québec, Canada (Drs Fombonne and Steiman); Thompson Center for Autism and Neurodevelopmental Disorders, University of Missouri, Columbia (Dr Miles); Department of Pediatrics, Baylor College of Medicine, Houston, Texas (Drs Kanne and Goin-Kochel); Institute for Juvenile Research, Department of Psychiatry, University of Illinois at Chicago (Dr Cook and Mr Guter); Cincinnati Children’s Hospital Medical Center, Ohio (Dr Bishop); Department of Pediatrics, University of Minnesota, Minneapolis (Dr Esler); and Department of Psychological and Brain Sciences, Indiana University, Bloomington (Dr Richler).
And here the abstract:
Best-estimate clinical diagnoses of specific autism spectrum disorders (autistic disorder, pervasive developmental disorder-not otherwise specified, and Asperger syndrome) have been used as the diagnostic gold standard, even when information from standardized instruments is available.
To determine whether the relationships between behavioral phenotypes and clinical diagnoses of different autism spectrum disorders vary across 12 university-based sites.
Multisite observational study collecting clinical phenotype data (diagnostic, developmental, and demographic) for genetic research. Classification trees were used to identify characteristics that predicted diagnosis across and within sites.
Participants were recruited through 12 university-based autism service providers into a genetic study of autism.
A total of 2102 probands (1814 male probands) between 4 and 18 years of age (mean [SD] age, 8.93 [3.5] years) who met autism spectrum criteria on the Autism Diagnostic Interview-Revised and the Autism Diagnostic Observation Schedule and who had a clinical diagnosis of an autism spectrum disorder. Main Outcome Measure Best-estimate clinical diagnoses predicted by standardized scores from diagnostic, cognitive, and behavioral measures.
Although distributions of scores on standardized measures were similar across sites, significant site differences emerged in best-estimate clinical diagnoses of specific autism spectrum disorders. Relationships between clinical diagnoses and standardized scores, particularly verbal IQ, language level, and core diagnostic features, varied across sites in weighting of information and cutoffs.
Clinical distinctions among categorical diagnostic subtypes of autism spectrum disorders were not reliable even across sites with well-documented fidelity using standardized diagnostic instruments. Results support the move from existing subgroupings of autism spectrum disorders to dimensional descriptions of core features of social affect and fixated, repetitive behaviors, together with characteristics such as language level and cognitive function.