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What Is Pervasive Developmental Disorder
- PDD
The term Pervasive Developmental Disorders was first used
in the 1980s to describe a group of disorders. This group
of disorders share several characteristics including impairments
in social interaction, impairments in imaginative activity,
delays or lack of receptive and expressive language skills,
impaired nonverbal communication skills, a limited number
of interests and activities that tend to be repetitive and
stereotyped, and repetitive and stereotyped motor mannerisms.
The current version of the Diagnostic and Statistical Manual
of Mental Disorders (DSM) published in the year 2000, is DSM-IV-TR,
identified five disorders under the category of PDD:
1. Autistic Disorder
2. Rett's Disorder
3. Childhood Disintegrative Disorder
4. Asperger's Disorder
5. Pervasive Developmental Disorder Not
Otherwise Specified, or PDDNOS
According to the definition set forth in the DSM-IV (American
Psychiatric Association, 1994), Pervasive Developmental Disorders
are characterized by severe and pervasive impairment in several
areas of development:
- Social interaction skills;
- Communication skills; or
- The presence of stereotyped behavior, interest, and activities.
(p.65)
The Five Types of PDD
1. Autistic Disorder.
Onset is in infancy or early childhood and is a lifelong
developmental disability. Autism is four times more prevalent
in boys than in girls. Children with the Autistic Disorder
have a moderate to severe range of communication, socialization,
behavior problems, and extreme reactions to sensory experiences.
Mental retardation is sometimes present. Symptoms of autism
can occur in isolation or in combination with other conditions.
Autism is a spectrum disorder meaning that every child will
exhibit individual symptoms that will vary in severity and
characteristics. The major characteristics displayed by
children with autism include: (a) the impairment in socialization
skills. Symptoms include impairment in the use of non-verbal
behaviors that regulate social interaction (i.e., eye contact,
body posture, and gestures); difficulty establishing age-appropriate
peer relationships; a lack of spontaneous seeking for shared
emotions, excitement and achievement; lack of social or
emotional reciprocity; (b) impairments in communication
Skills. Symptoms include delay or lack of verbal communication;
in verbal individuals, difficulty initiating or sustaining
a conversation with others; tangential speech; echolalia
(repetition of words and phrases); stereotyped and repetitive
use of language; limited or lack of spontaneous age-appropriate
make-believe play or social imitative play; lack of inflection
or intonation; questionable coexistence of apraxia of speech;
and (c)the presence of repetitive and stereotyped patterns
of behavior, interests, and activities. Symptoms include
obsessive preoccupation with one or more stereotyped patterns
of interest which is abnormal in intensity and/or focus;
inflexibility and difficulty transitioning away from the
specific, non-functional routines or rituals exhibited;
stereotyped and repetitive motor mannerisms; persistent
preoccupation with parts of objects.
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2. Rett's Disorder or Rett's Syndrome.
Primarily diagnosed in females. Onset appears to fall around
the age of 18 months. Prenatal and perinatal development
in psychomotor development and head circumference appear
to be normal from birth to 5 months of age. A deceleration
of head circumference is noted from the ages of 5 to 48
months. Regression or loss of previously acquired abilities
is mostly prevalent in gross motor skills followed by deterioration
in receptive and expressive language development, reasoning,
and hand use. An important clue in the diagnosis of Rett's
Syndrome is the presence of meaningless repetitive motor
patterns and mannerisms such as hand-wringing or hand-washing.
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3. Childhood Disintegrative Disorder.
A very rare disorder which is characterized by an apparent
regression in psychomotor development, loss of bowl and
bladder control, gross motor skills, social skills, receptive
and expressive language skills. Onset is around the age
of 2 years. The diagnosis can only be made if the onset
of the symptoms are preceded by at least 2 years of normal
development and the onset decline is prior to age 10 years.
In addition, other disorders such as Pervasive Developmental
Disorder or Schizophrenia need to be ruled-out prior to
making such a diagnosis.
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4. Asperger's Disorder or Asperger's
Syndrome.
Also referred to as "high functioning autism",
Asperger's Disorder is a developmental disorder that appears
to have a somewhat later onset than Autistic Disorder, or
at least is recognized later. Asperger's Disorder is characterized
by a qualitative impairment in social interaction; difficulty
with social relationships; difficulty with social-emotional
reciprocity; difficulty spontaneously seeking shared enjoyments
and achievements; poor coordination and poor concentration;
restricted range of interest; intensive preoccupation with
one or more stereotyped and restricted patterns of interest;
apparent inflexibility in adhering to nonfunctional routines
or rituals; stereotyped and repetitive motor mannerisms;
no clinically significant delay in language and cognitive
development and development of self-help skills and adaptive
behaviors; however, some difficulty understanding subtleties
used in conversation and abstract concepts. While mental
retardation is sometimes found in individuals with autism,
a person with Asperger's possesses an average to above average
intelligence.
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5. Pervasive Developmental Disorder Not Otherwise Specified-PDDNOS.
PDDNOS is a neurological disorder with an unidentified
cause or causes. The diagnosis of PDDNOS is primarily based
on a behavioral assessment. There is clinical evidence suggesting
that Autistic Disorder and PDDNOS are on a continuum, therefore,
children with autism or PDDNOS will share many of the clinical
features described above, but will vary in their types and
severity. One major difference is that children with PDDNOS
are generally able to show extreme emotions of joy, fear,
or anger, but will have difficulty displaying the subtle
facial emotional expressions; however, it is not unusual
that a child with PDDNOS displays flattened or inappropriate
emotional expressions. The diagnosis is made when a child
exhibits symptoms that do not fully meet the DSM-IV criteria
of symptoms used to diagnose any of the four above mentioned
types of PDD, and/or do not have the degree of impairment
specified. According to the DSM-IV, this category should
be used "when there is a severe and pervasive impairment
in the development of social interaction or verbal and nonverbal
communication skills, or when stereotyped behavior, interests,
and activities are present, but the criteria are not met
for a specific Pervasive Developmental Disorder, Schizophrenia,
Schizotypal Personality Disorder, or Avoidant Personality
Disorder" (American Psychiatric Association, 1994,
pp. 77-78). It is important to recognize that children differ
in the range and severity of symptoms they exhibit.
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