Asperger Syndrome and Nonverbal Learning Disabilities

Asperger syndrome (AS) and Nonverbal Learning Disabilities (NLD) are developmental disorders that involve some common areas of difficulty, including social interactions and nonverbal communication. The controversy surrounding the precise diagnostic criteria for AS and NLD, as well as the degree of overlap between the two syndromes, can be confusing for parents and professionals alike. This article will discuss the definition and clinical picture of Asperger syndrome, and then explore the similarities between Asperger syndrome and the syndrome of Nonverbal Learning Disabilities.

Asperger Syndrome: Definition and Clinical Picture

Asperger syndrome is a neurologically-based disorder of development, which is usually of unknown cause. It was first described by Hans Asperger, a Viennese pediatrician, in the 1940's, but it was not widely recognized or well studied until the past two decades. AS is one of the autism spectrum disorders (also called the pervasive developmental disorders, or PDDs). Each of the autism spectrum disorders involves difficulties in three areas of development: social interactions, use of language for social communication, and behaviours and interests (tendency to show repetitive behaviours and intense, narrowly restricted interests). Another associated feature of AS may be motor clumsiness affecting both gross and fine motor skills.

Asperger syndrome is a disorder at the less pervasive end of the autism spectrum. AS is distinguished from other autism spectrum disorders by relatively higher cognitive abilities and language skills. There is ongoing debate among professionals in the field of child development about whether or not AS is distinct from "high-functioning autism", and about the specific criteria for cognitive and language development that are required to make a diagnosis of AS. Although most individuals with AS have intelligence within the broad range of normal, some can have particular areas of learning difficulty (see below), while others have intelligence in the superior range.

The social interactions of individuals with AS are characterized by difficulty interpreting and responding to social cues. Individuals with AS can appear to be always following their own agenda, because of difficulty sensing and understanding the perspectives or feelings of other people and/or difficulty shifting from one topic or activity to another. Some children with AS may have decreased interest in interacting with their peers; others may be interested, but have difficulty forming friendships because of their lack of social insight, which leads to ineffective social skills.

Although individuals with AS can often develop a large vocabulary and can use appropriate sentence structure, the way they use language to communicate is unusual. They have difficulty modulating the rate, volume and rhythm of their speech, and might speak very fast, or in a monotone voice, or in an overly formal manner. They have difficulty with turn-taking in conversation, and have a tendency to revert to topics of special interest. They also tend to be very concrete and take things literally.

Nonverbal communication is also difficult for individuals with AS. They may have limited or exaggerated use of gesture and body language, and difficulty reading these cues in others. They may avoid or dislike direct eye contact, and may show limited or inappropriate facial expressions.

The behavioural characteristics of individuals with AS include insistence on particular routines, and the presence of unusual motor mannerisms (finger flicking, body rocking, etc). Intense preoccupations with areas of particular interest are also typical of AS. These areas of interest can be unusual, such as a preoccupation with fans or sliding doors. In other cases, the areas of interest are not unusual, but the topic dominates the individual's time and interferes with normal social interaction to an unusual degree. For example, a child with AS who was interested in trains would not just collect toy trains or watch TV shows about trains, but might memorize train schedules and routes, or learn all the parts of a train engine. These intense interests can be associated with outstanding abilities or talents in a particular area.

Asperger Syndrome and Nonverbal Learning Disabilities

The syndrome of Nonverbal Learning Disabilities consists of difficulty in the acquisition and use of academic skills and life skills, due to deficits in the following areas: visual-spatial organization, interpreting visual and tactile information, nonverbal problem solving, and motor coordination for complex tasks. These areas of relative weakness lead to difficulties in adapting to new situations, social difficulties due to poor understanding of nonverbal communication, and problems academically in the areas of mathematics, handwriting and reading comprehension. Individuals with NLD have strengths in the areas of interpretation of auditory information, vocabulary, and verbal memory, with academic success in reading decoding and spelling. This pattern of strengths and weaknesses generally leads to higher scores on the verbal portion of the IQ tests than on the performance (nonverbal reasoning) sections.

The areas of difficulty present in NLD produce some of the same symptoms that are seen in children with AS. The inability to understand and respond to nonverbal communication (for example, facial expressions and gestures) leads to problems with conversational turn-taking, responding to others' feelings, and staying on topic. These communication difficulties affect social interactions, and this can eventually lead to social withdrawal. Difficulty understanding new situations produces a tendency to return to favorite topics and activities. Motor difficulties lead to clumsiness and difficulty learning fine motor skills.

Because of the similarities between the symptoms seen in AS and NLD, research is ongoing to determine the extent of the overlap between the two syndromes. What is clear is that there are some individuals who meet criteria for both AS and NLD. Different studies, however have reached different conclusions about the proportion of children with AS who also show the learning deficits associated with NLD, and the proportion of children with NLD who have social and communication deficits to a degree that would fit the criteria for AS. Some researchers feel that NLD is the cognitive profile found in all individuals with strictly-defined AS, while others feel that the two syndromes are distinct, but overlapping. The ongoing debate surrounding the specific diagnostic criteria for both AS and NLD contributes to the varying opinions on this matter.

Summary

Asperger syndrome and Nonverbal Learning Disabilities are neurologically based developmental disorders which produce many similar symptoms, including difficulties with nonverbal communication, awkward social interactions and motor clumsiness, in the context of superficially strong verbal skills. AS is diagnosed by assessment by an experienced clinician of impairments in the areas of reciprocal social interactions and communication, as well as a tendency to have intense, narrow interests and repetitive behaviours. NLD is defined and diagnosed by assessment of cognitive and academic functioning, with deficits in the areas of psychomotor coordination, visual-spatial organization and nonverbal problem solving. There is clearly some degree of overlap between the two syndromes. Some children with AS will also meet criteria for NLD, and vice-versa. More research is required to clarify how many individuals would fit into both categories, and whether or not the two syndromes are distinct, or just different sides of the same problem. It is important that any individual with AS, NLD, or symptoms suggestive of either diagnosis, have broad-based assessments that consider their cognitive and academic abilities, as well as their social and communication skills, in order that appropriate, individually-tailored interventions and support services can be provided.

References

Ehlers, S, Nyden, A, Gillberg, C, Sandberg, AD, Dahlgren, S-O, Hjelmquist, E, Oden, A: Asperger Syndrome, Autism and Attention Disorders: A comparative study of the cognitive profiles of 120 children. J Child Psychol Psychiatry 1997; 38(2): 207-217.

Harnadek, MCS, Rourke, BP: Principal identifying features of the syndrome of nonverbal learning disabilities in children. Journal of Learning Disabilities 1994; 27(3): 144-154.

Klin, A, Volkmar, FR, Sparrow, SS, Cicchetti, DV, Rourke, BP: Validity and neuropsychological characterization of Asperger syndrome: convergence with nonverbal learning disabilities syndrome. J Child Psychol Psychiatry 1995; 36(7): 1127-1140.

Volkmar, FR, Klin, A, Schltz, RT, Rubin, E, Bronen, R: Asperger's Disorder. Am J Psychiatry 2000; 157(2): 262-7.

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