NLD or Asperger Syndrome?

by Pamela B. Tanguay

A question which comes up with parents over and over again is what is the difference between NLD and Asperger Syndrome (AS)?  Although there has not been a clear delineation provided by the professionals, there are some points which may help parents understand why these disorders are so often linked.

What distinguishes these disorders is often more a question of who provides the diagnosis, rather than clearly defined distinctions between NLD and AS.

AS is diagnosed within the field of psychiatry, and is defined in the DSM-IV (published by the American Psychiatric Association) along with four other disorders which make up the classification of pervasive developmental disorders.  The three we hear most about are AS, autism, and PDD-NOS (Pervasive Developmental Disorder – Not Otherwise Specified). It is important to remember that the DSM-IV criteria is based on observed behaviors, as interpreted by the diagnosing clinician.  The defining line between AS, autism, and PDD-NOS seems to depend on the clinician's interpretation of the DSM-IV, and more recently the DSM-IV-TR, criteria. Yale is trying to identify what distinguishes AS from autism, and proposes that AS and high functioning autism are somewhat mirror images of each other in terms of neuropsychological assets and deficits, with AS sharing a common neuropsychological profile with NLD.

NLD is defined within the field of neuropsychology, and is diagnosed based on a battery of tests administered to the individual.  It is not diagnosed based on the subjective interpretation of observed behaviors.  Dr. Byron Rourke, cites in his 1995 book, Syndrome of Nonverbal Learning Disabilities:  Neurodevelopmental Manifestations, that several neurological disorders and diseases result in NLD, and classifies them as to how closely each of them share the NLD profile.  AS is considered a "Level 1" NLD, meaning that virtually all of the NLD assets and deficits are present.  An interesting note - Dr. Rourke is a member of the Yale research team mentioned in the prior paragraph.

Psychiatrists and/or psychologists often say that NLD isn't an actual diagnosis, but rather a learning profile, while neuropsychologists firmly believe that NLD is a diagnosis.  In my opinion, this seems to be political hair-splitting over whether NLD is a "profile" or a diagnosis.  Although this may be a very controversial topic among professionals, they all seem to agree that, at the very least, there is significant overlap between NLD and AS, and recommend NLD educational interventions.

An interesting point is that there is a 1:1 incidence of NLD in boys and girls, versus AS and autism which have an incidence of far more boys than girls.  Is this difference in incidence data because an NLD diagnosis is based on objective versus subjective measures?  Is the AS and autism phenotype weighted towards males?  Thoughts to ponder.

This brings us back to the first point - whether an individual receives an NLD or AS diagnosis often depends on what professional sees the child - a neuropsychologist or psychiatrist/psychologist.

Copyright:  Pamela B. Tanguay

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