Questions and Answers
Question # 3
Does the NLD syndrome appear in any taxonomies or classification
systems of medical or developmental disorders, such as the
International Classification of Diseases?
At present, there is no entry
in the International Classification of Diseases (ICD; currently
in its 10th revision) for the NLD syndrome. Were NLD to be added
in some future revision of that classification system, the
following is a proposed description of NLD that could be
considered for inclusion.
Proposed ICD Definition of NLD
The syndrome of Nonverbal Learning Disabilities (NLD) is characterized by significant primary deficits in some dimensions of tactile perception, visual perception, and complex psychomotor skills, and in dealing with novel circumstances. These primary deficits lead to secondary deficits in tactile and visual attention and to significant limitations in exploratory behavior. In turn, there are tertiary deficits in tactile and visual memory and in concept-formation, problem-solving, and hypothesis-testing skills. Finally, these deficits lead to significant difficulties in the content (meaning) and function (pragmatics) dimensions of language. In contrast, neuropsychological assets are evident in most areas of auditory perception, auditory attention, and auditory memory, especially for verbal material. Simple motor skills are most often well developed, as are rote verbal memory, language form, amount of verbal associations and language output. This mix of neuropsychological assets and deficits eventuates in some formal learning (e.g., academic) assets, such as single-word reading and spelling. It also increases the likelihood of significant difficulties in other aspects of formal learning (e.g., arithmetic, science) and informal learning (e.g., as transpires during play and other social situations). Psychosocial deficits, primarily of the externalized variety, often are evident early in development; psychosocial disturbances, primarily of the internalized variety, are usually evident by late childhood and adolescence and into adulthood.
Proposed ICD Diagnostic Criteria for Research in NLD
1. Bilateral deficits in tactile perception, usually more marked on the left side of the body. Simple tactile perception may approach normal levels with advancing years, but interpreting complex tactile stimulation remains impaired.
2. Bilateral deficits in psychomotor coordination, usually more marked on the left side of the body. Simple, repetitive motor skills may reach normal levels with age, but complex motor skills remain impaired or worsen relative to age norms.
3. Extremely impaired visual-spatial-organizational abilities. Visual discrimination can reach normal levels with age, particularly when stimuli are relatively simple. Compared to age norms, complex visual-spatial-organizational abilities tend to worsen substantially with advancing years.
4. Substantial difficulty in dealing with novel or complex information or situations. A strong tendency to rely on rote, routinized approaches and memorized responses (often inappropriate for the situation), and failure to learn or adjust responses according to potentially corrective informational feedback. Also, especially frequent use of rote verbal responses in spite of the nonverbal requirements of the novel situation. These tendencies remain or worsen with age.
5. Notable impairments in nonverbal problem-solving, concept-formation, and hypothesis-testing.
6. Distorted sense of time. Estimating elapsed time over an interval and estimating time of day are both notably impaired.
7. Well-developed rote verbal abilities (e.g., single-word reading and spelling), frequently superior to age norms, in the context of notably poor reading comprehension abilities (particularly evident in older children).
8. High verbosity that is rote and repetitive, with content/meaning disorders of language and deficits in the functional/pragmatic dimensions of language.
9. Substantial deficits in mechanical arithmetic and reading comprehension relative to strengths in single-word reading and
10. Extreme deficits in social perception, social judgment, and social interaction, often leading to eventual social isolation/withdrawal. Easily overwhelmed in novel situations, with a marked tendency toward extreme anxiety, even panic, in such situations. High likelihood of developing internalized forms of psychopathology (e.g., depression) in late childhood and adolescence.
Characteristics Particularly Evident in Younger Children
(up to six years)
A. Delays in reaching all developmental milestones, including acquisition of speech, followed by a late but rapid development of speech and some other verbal abilities (particularly of the rote variety), usually to above-average levels.
B. Below normal amount of exploratory behavior. Often, an apparent aversion for any type of exploration of new stimuli/situations.
C. Impaired development of complex psychomotor skills (e.g., climbing, walking).
D. Avoidance of novelty, and preference for highly familiar objects, situations, and information.
E. Preference for receiving information in verbal as opposed to visual format.
F. Relative strengths in simple, stereotyped motor activities (e.g., static steadiness) and in rote verbal memory (e.g., reciting the alphabet).
G. Deficits in perception and attention in both the visual and tactile domains.
H. Notably better auditory-verbal memory than visual or tactile memory.
I. Initial problems in oral-motor praxis, and longstanding, mild difficulties in pronouncing complex, polysyllabic words. Frequently described as "hyperactive" and/or "inattentive."
Characteristics Particularly Evident in Older Children (seven years
A. Impaired capacity to analyze, organize, and synthesize information, with associated impairments in problem-solving and concept-formation.
B. Despite high levels of verbosity, there are very evident and significant impairments in language prosody, content, and pragmatics. This is often manifest in the form of "cocktail-party" speech patterns, with high volume of verbal output but relatively little content (meaning) and exceedingly poor psycholinguistic function/pragmatics.
C. Strengths in single-word reading/recognition and spelling, but substantially worse performance in reading comprehension and mechanical arithmetic.
D. Very poor handwriting in early school years, often improving to normal levels but only with considerable practice.
E. Spelling errors predominantly--even, almost exclusively--of the phonetically accurate variety.
F. Deficient social perception, social judgment, and social interaction.
G. Poor perception and comprehension/interpretation of facial expressions of emotion, as well as marked deficits in providing non-verbal communication signals.
H. With advancing years, a tendency to become normoactive and then hypoactive. Problems in "attention" in formal and informal learning environments tend to disappear as the situational stimulus and response demands become more verbal in nature.
The interested reader may wish to compare and contrast the above criteria with those for Asperger's Syndrome contained in ICD-10.