AUTISM

I. Also known as "Pervasive Developmental Disorder"--A set of developmental abnormalities affective social, verbal, and nonverbal function, and involving rigid repetitive behaviors.  There are many possible underlying causes.  Usually grouped into the following categories:

1. Autistic Disorder--The most "classic" of the PDDs; often, though not exclusively, associated with inability to live independently as an adult
2. Asperger Disorder--Difficulties are centered around social interactions; tend to have narrow interests; IQ usually > 70
3. Disintegrative Disorder--Characterized by normal development until onset at 2-10yo followed by severe regression
4. Rett Syndrome--X-linked; seen almost exclusively in girls; characterized by severe mental retardation; also usually by severe motor deficits and epilepsy
5. PDD not otherwise specified--Used to describe those who don't fit into one of the other categories

II. Symptomatology

1. Verbal function
   1. Failure to develop, or regression of, verbal expression or communicative gestures (with hands or head, e.g. head shaking to indicate "no")
   2. Mutism unpredictably interrupted by clearly-articulated words
   3. Lack of speech comprehension
   4. Inability to speak conversationally or tell a story, i.e. speaks but without apparent intent to communicate
      1. Echolalia (frequent, persistent, verbatim repetition of words or sounds)
      2. "Formulaic" speech (repeats learned expressions, especially technical or pedantic expressions, rather than generating his/her own expressions appropriate to the situation)
   5. Pronoun inversion (e.g. interchanging "you" and "me")
   6. Perseveration on a particular topic of speech
   7. Persistently high-pitched, sing-song, or uninflected ("robotic") speech
2. Social function
   1. Unprovoked aggression
   2. Severe tantrums
   3. Lack of attention to or acknowledgement of others
3. Nonverbal function
   1. Monotonous, unimaginative play
   2. Adherence to rigid routines with temper tantrums if these are interrupted
   3. Stereotyped motor behavior (e.g. rocking, hand flapping)
   4. "Clumsiness"
   5. Intolerance to loud sounds

III. Probable/known causes--Generally < 20% of cases have an idenfitiable cause

1. Infections (rubella, cytomegalovirus, herpes simplex)
2. Ischemic brain damage
3. Thalidomide exposure in utero
4. Tuberous sclerosis
5. Untreated phenylketonuria
6. Fragile X syndrome
7. Lead poisoning

(Sources include JAMA 285:1749, 2001--AFP)