31.5 Autism Spectrum Disorder
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several months of intellectual, social, and language function
occurring in 3- and 4-year-olds with previously normal func-
tion. After the deterioration, the children closely resembled chil-
dren with autistic disorder.
Epidemiology.
Epidemiological data have been compli-
cated by the variable diagnostic criteria used, but childhood dis-
integrative disorder is estimated to be much less common than
the formerly diagnosed autistic disorder. The prevalence has
been estimated to occur in about 1 in 100,000 boys. The ratio
of boys to girls is estimated to be between 4 and 8 boys to 1 girl.
Etiology.
The cause of childhood disintegrative disorder is
unknown, but it has been associated with other neurological
conditions, including seizure disorders, tuberous sclerosis, and
various metabolic disorders.
Diagnosis and Clinical Features.
The diagnosis is made
based on features that fit a characteristic age of onset, clinical
picture, and course. Cases reported have ranged in onset from
ages 1 to 9 years, but in most, the onset is between 3 and 4 years.
Whereas previously diagnosed as a separate entity, DSM-5 con-
ceives of childhood disintegrative disorder as a subset of autism
spectrum disorder. The onset may be insidious over several
months or relatively abrupt, with abilities diminishing in days
or weeks. In some cases, a child displays restlessness, increased
activity level, and anxiety before the loss of function. The core
features of the disorder include loss of communication skills,
marked regression of reciprocal interactions, and the onset of
stereotyped movements and compulsive behavior. Affective
symptoms are common, particularly anxiety, as is the regression
of self-help skills, such as bowel and bladder control.
To receive the diagnosis, a child must exhibit loss of skills
in two of the following areas: language, social or adaptive
behavior; bowel or bladder control; play; and motor skills.
Abnormalities must be present in both of the following catego-
ries: reciprocal social communication skills, and restricted and
repetitive behavior. The main neurological associated feature is
seizure disorder.
integrative disorder is characterized by the loss of previously
acquired development. Before the onset of childhood disinte-
grative disorder (occurring at 2 years or older), language has
usually progressed to sentence formation. This skill is strikingly
different from the premorbid history of even high-functioning
patients with autistic disorder, in whom language generally does
not exceed single words or phrases before diagnosis of the dis-
order. Once the disorder occurs, however, those with childhood
disintegrative disorder are more likely to have no language abil-
ities than are high-functioning patients with autistic disorder.
In Rett syndrome, the deterioration occurs much earlier than
in childhood disintegrative disorder, and the characteristic hand
stereotypies of Rett syndrome do not occur in childhood disin-
tegrative disorder.
Course and Prognosis.
The course of childhood disin-
tegrative disorder is variable, with a plateau reached in most
cases, a progressive deteriorating course in rare cases, and some
improvement in occasional cases to the point of regaining the
ability to speak in sentences. Most patients are left with at least
moderate mental retardation.
Treatment.
Treatment of childhood disintegrative disorder
includes the same components available in the treatment of
autistic disorder.
Asperger’s Disorder
The former diagnosis of Asperger’s disorder is characterized
by impairment and oddity of social interaction and restricted
interest and behavior. Unlike the former autistic disorder, in
Asperger’s disorder there are no significant delays in language
or cognitive development. In 1944, Hans Asperger, an Austrian
physician, described a syndrome that he named “autistic psy-
chopathy.” His original description of the syndrome described
individuals with normal intelligence who exhibit a qualitative
impairment in reciprocal social interaction and behavioral
oddities without delays in language development. Asperger’s
disorder occurs in a wide variety of severities, including cases
in which very subtle social cues are missed, but overall social
interactions are mastered.
Etiology.
Asperger’s disorder, a version of autism spectrum
disorder, has a complex etiology including genetic contribu-
tion and potentially environmental and perinatal contributing
factors.
Diagnosis and Clinical Features.
The clinical features
include at least two of the following indications of qualitative
social impairment: Markedly abnormal nonverbal communi-
cative gestures, the failure to develop peer relationships at the
expected level. Restricted interests and patterns of behavior are
present, but when they are subtle, they may not be immediately
identified or singled out as different from those of other chil-
dren. According to DSM-IV-TR, individuals with Asperger’s
disorder exhibit no language delay, clinically significant cogni-
tive delay, or adaptive impairment. Currently, the clinical phe-
notype of Asperger’s disorder is subsumed within the DSM-5
diagnosis of autism spectrum disorder.
Ron’s early history was within normal limits. By age 2, he was
speaking in sentences, and his development appeared to be pro-
ceeding appropriately. At 3½ years of age, he abruptly exhibited a
period of marked behavioral regression shortly after the birth of a
sibling. Ron lost previously acquired skills in communication and
was no longer toilet trained. Ron became more withdrawn and less
interested in social interaction, exhibiting various self-stimulatory
behaviors repeatedly. Comprehensive medical examination failed
to reveal any conditions that might account for this developmental
regression. Behaviorally, Ron exhibited features of autism spec-
trum disorder. At follow-up at age 12, he spoke only an occasional
single word and had severe mental retardation. (Adapted from Fred
Volkmar, M.D.)
Differential Diagnosis.
The differential diagnosis of the
formerly diagnosed childhood disintegrative disorder includes
receptive and expressive language disorder, mental retardation
with behavioral problems, and Rett syndrome. Childhood dis-
