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Summary: NeuroDevelopmental Disorders

Down Syndrome is the most common genetic disorder that causes intellectual deficits and other problems. It is due to a defect of chromosome 21.

Because Down Syndrome is diagnosed with certainty by this defect, DSM-5 (a diagnostic manual) does not give much attention to it. However, children with Down Syndrome are common in special education classrooms, and some of them mainstream in regular courses. Outcomes vary, but some people with Down Syndrome do well enough in school to attend college.

Autism is a genetically based syndrome that is diagnosed by a distinctive pattern of behaviors in early childhood, such as a fascination with spinning objects, gaze aversion, echolalia, and a tendency to be greatly disturbed by changes in the environment. The full array of autistic symptoms was first spelled out by Leo Kanner in the 1940s.

DSM-5 categorizes autism as a spectrum disorder. On one end of the spectrum are profoundly disabled individuals with very limited speech (about 40% of the total).

On the other end of the spectrum are near-normal people who may have some difficulties in social situations but are able to function well and hold jobs. Near-normal autistic people are some­times labeled as having Asperger's Syndrome, although that term was dropped from DSM-5.

An autistic savant is an autistic person with an exceptional skill. Usually these skills involve music, art, or mathematics. These skills can enable an autistic person with moderate handicaps to lead a productive life.

Attention Deficit/Hyperactivity Disorder (ADHD) is characterized by problems paying attention and concentrating on a task, as well as by restless activity. It is most common in boys. Stimulant drugs (first Ritalin and more recently Adderall) have been widely used to treat children with ADHD. Paradoxically, the stimulants slow down a child with ADHD by allowing the child to focus and concentrate.

Learning disorders such as dyslexia affect a specific skill. Dyslexia is the common label for problems in reading.

Researchers apply the term dyslexia mostly to difficulties in phonological encoding (sounding out words). When older people are called dyslexic, the problem may be comprehension difficulties. Sometimes people can find ways to compensate and overcome the effects of dyslexia.

Many other learning disorders exist but are not as common as dyslexia. DSM-5 restricts the term learning disorders to language and mathematics problems that impede progress at school, but deficits in music understanding, foreign language learning, and motor coordi­nation could also be categorized as learning disorders from a cognitive or biological perspective.

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