ASPERGER's DISORDER AND NONVERBAL LEARNING DISABILITIES:
How are These Two Disorders Related to Each Other? 

by David Dinklage, PhD 

There is clearly a great deal of overlap between Asperger’s Disorder (AD) and Nonverbal Learning Disabilities (NVLD) – so much so that it is possible that the symptoms of each diagnosis describe the same group of children from different perspectives, AD from either a psychiatric/behavioral perspective, and NVLD from a neuropsychological perspective.  The specific conventions of these diagnoses may lead to a somewhat different group of children meeting diagnostic criteria, but it is not clear that this reflects something “true” in nature.  That is, it may only be convention that separates these two groups.

One is reminded of the story of the six blind men who were asked to describe an elephant.  Each man grabbed a different part of the creature (the snake-like trunk vs. the tree-like leg), and gave an accurate description from his own particular perspective – but each man thought the others were completely mistaken!

Studies conducted by the Yale Child-Study Group suggest that up to 80% of children who meet the criteria for AD also have NVLD.  While there are no studies on overlap in the other direction, most likely children with the more severe forms of NVLD also have AD.  Children from both groups are socially awkward and pay over-attention to detail and parts, while missing main themes or underlying principles.  However, by convention, the two groups differ in the range of severity.  Professionals reserve an AD diagnosis for children with more severe social impairment and behavioral rigidity; some symptoms may overlap with high functioning autism.  There are degrees of severity within AD but not to the extent that is acceptable in diagnosing NVLD.  These degrees can range from extreme autistic behavior to cases where the social difficulties are very subtle and the academic/cognitive difficulties are more prominent.

Here is a brief outline of the diagnostic criteria for AD and the pattern of neuropsychological findings in NVLD.  While the overlap is apparent, the emphasis is different because criteria for NVLD focuses on academic issues as well as specific test findings and is not purely descriptive.  This also results in different means of making the diagnosis (testing vs. observing).

Asperger's Disorder (AD) is characterized by:

A.    Qualitative impairment in social interaction, including:

  1. Failure to use non-verbal social skills (i.e. eye contact, gestures, body posture, facial expressions).

  2. Developmentally inappropriate peer relationships.

  3. Lack of spontaneous sharing of enjoyment and interests with other people.

  4. Lack of social and emotional reciprocity. 

B.    Restricted, repetitive and stereotyped patterns of behavior, interests, and activities: 

  1. Preoccupation that is overly intense and narrow.

  2. Inflexible adherence to non-functional or peripheral routines.

  3. Stereotypic or repetitive motor movements.

  4. Persistent preoccupation with parts of objects.

C.    These problems taken together (A plus B) present significant challenges in the lives of people with AD as they attempt to live in a “neurotypical” world and meet the expectations of others.

D.    There is no general language delay.

E.    There is no severe global cognitive impairment.


Nonverbal Learning Disabilities (NVLD)

  Academics  

  Social/Emotional Issues

Assessment of NVLD Compared with Assessment of AD

In my practice I have seen a number of children with AD who would not meet the criteria for NVLD in any previous research studies.  If these children had participated in the Yale study mentioned earlier in this article, they would probably have been in the 20% of the AD children who did not meet the NVLD criteria.  It is possible that the AD children in that 20% may have had very high visual/spatial scores, thus masking their over-attention to detail in problem solving.  For example, they may have scored very high on the Block Design subtest of the IQ measure (using colored blocks to match a pattern given to them) despite having little or no appreciation of the gestalt; their considerable skill and speed at analyzing detail would have allowed them to use this inefficient strategy effectively.  With these very bright children, it may be that the tests are not sufficiently sensitive to discern a pattern of NVLD.  On the other hand, some children with AD show diffuse difficulties in language and attention domains, but may not exhibit the pronounced discrepancies associated with NVLD.  Nonetheless, they may still struggle with the cognitive difficulties similar to those of someone with NVLD.  Conversely, a child meeting the criteria for NVLD may not meet the Asperger’s Disorder criteria “C,” even though subtle characteristics of AD may be present.

A case example best illustrates how children who clearly have NVLD may not meet the criteria for AD as it is presently understood.  I evaluated an eighth grade girl whose parents were concerned about her math performance.  She had above average overall ability, but a 24-point discrepancy between her verbal and visual/spatial skills on the IQ measure.  On the neuropsychological measures, she clearly had the pattern of visual/spatial deficits, left sided motor slowing, and poor math ability, while language skills were intact.  She did not have any problems with inferential comprehension in reading.  One would not even have considered Asperger’s Disorder.  She had had many good friends through elementary school and felt herself to be part of her peer group.  Symbolic play development had been normal and she exhibited no repetitive behaviors.  This is unusual in NVLD as well, but since many of the criteria for this neuropsychological diagnosis are cognitive and test-based, it was determined that she met enough of the criteria for a diagnosis of NVLD.  I commented in the report that, unlike this girl, most children with NVLD have more social problems, tend to miss the point in social interactions, and have trouble in content areas in school because of inferential reading comprehension problems.

The parents came back to me when the girl was a senior.  Now things looked rather different.  She was now isolated from her peers, who complained that she was too literal.  She was struggling in literature and social studies; her papers tended to be more like lists, less integrated than those of her peers.  I don’t believe she was developing a new disorder.  She had classic NVLD, but it was relatively subtle and it required more high-powered peer and academic demands to highlight her social perception and inferential reasoning weaknesses.  (This is similar to the way that some mildly dyslexic individuals compensate reasonably well and go unnoticed until they go to college and flunk out during their freshman year.)  Given her history of good social adjustment, one would never diagnose this student with AD.  Still one has to wonder whether her neurocognitive functioning indicated AD, but in a much milder form.

Asperger’s Disorder was not originally thought of as having a continuum of severity that included these subtle forms, whereas NVLD did not start with the assumption of more extreme difficulties.  As information about AD becomes more widely circulated, and increasingly more subtle cases are being identified, the culture is in some manner changing the original “intention” of the category.  While that may dilute the clarity of the diagnosis, it will more accurately reflect the variety of developmental presentations in nature.  As humans, we naturally want to categorize.  The complex relationship between NVLD and AD may be an example of how categorizing too rigidly can confuse, rather than clarify, our thinking.

© 2001, David Dinklage.

David Dinklage, PhD, is Director of Neuropsychology and Co-Director of Training in Child Psychology at Cambridge Hospital in Massachusetts. He is also an Instructor in Psychology at the Harvard Medical School, and carries on a private clinical practice in Belmont, Massachusetts.