This description of PDD and autism is from the DSM (Diagnostic and Statistical Manual of Mental Disorders). It may seem somewhat pessimistic, but we need to remember that in order to diagnose the disorder, the psychiatrist must focus on the "problem behaviors". Remember that children are not defined only by their "label"; children will have strengths that will help them cope with the problems that their disorder gives them. We must be aware of, but never governed by the described limitations of this disorder.
 
DSM IV Descriptions:
 
Autistic Disorder (299.00) and Asperser's Disorder (299.80):
Diagnostic criteria for 299.00 Autistic Disorder
A. A total of six (or more) items from (1), (2), and (3), with at lest two from (1), and one each from (2) and (3):

1. Qualitative impairment in social interaction, as manifested by at least two of the following:
(a) Marked impairment in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body postures and gestures to regulate social interaction.
(b) Failure to develop peer relationships appropriate to developmental level
(c) A lack of spontaneous seeking to share enjoyment, interests or achievements with other people (e.g. by a lack of showing, bringing, or pointing out objects of interest)
(d) Lack of social or emotional

2. Qualitative impairments in communication as manifested by at least one of the following:
(a) Delay in, or total lack of the development of spoken language (not accompanied by an attempt to compensate through alternative modes of communication such as gesture or mime)
(b) In individuals with adequate speech, marked impairment in the ability to initiate or sustain a conversation with others
(c) Stereotyped and repetitive use of language or idiosyncratic language
(d) Lack of varied, spontaneous make believe play or social imitative play appropriate to developmental level
 
3. Restricted repetitive and stereotyped patterns of behavior, interests and activities, as manifested by at least one of the following:
(a) Encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus.
(b) Apparently inflexible adherence to specific nonfunctional routines or rituals
(c) Stereotyped and repetitive motor mannerisms (e.g. hand or finger flapping or twisting, or complex whole-body movements.)
(d) Persistent preoccupation with parts of objects.
B. Delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years: (1) social interaction. (2) Language as used in social communication, or (3) symbolic or imaginative play.
C. The disturbance is not better accounted for by Rett's Disorder or Childhood Disintegrative Disorder.

Diagnostic criteria for 299.80 Asperger's Disorder
A. Qualitative impairment in social interaction, as manifested by at least two of the following:
(1) Marked impairment in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body postures and gestures to regulate social interaction.
(2) Failure to develop peer relationships appropriate to developmental level
(3) A lack of spontaneous seeking to share enjoyment, interests or achievements with other people (e.g. by a lack of showing, bringing, or pointing out objects of interest to other people)
(4) Lack of social or emotional reciprocity
B. Restricted repetitive and stereotyped patterns of behavior, interests, and activities, as manifested by at lest one of the following:
(1) Encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus
(2) Apparently inflexible adherence to specific, nonfunctional routines or rituals
(3) Stereotyped and repetitive motor mannerisms (e.g., hand or finger flapping or twisting, or complex whole-body movements)
(4) Persistent preoccupation with parts of objects
C. The disturbance causes clinically significant impairment in social, occupational, or other important areas of functioning.
D. There is no clinically significant general delay in language (e.g., single words used by age 2 years, communicative phrases used by age 3 years).
E. There is no clinically significant delay in cognitive development or in the development of age-appropriate self-help skills, adaptive behavior (other than in social interaction), and curiosity about the environment in childhood.
F. Criteria are not met for another specific Pervasive Developmental Disorder or Schizophrenia.
 
Overall, a gross and sustained impairment in social interaction and restricted, repetitive and stereotyped patterns of behavior, interests and Recreation, occurring in the context of preserved cognitive and language development.
 
Pervasive Developmental Disorder Not Otherwise Specified (including Atypical Autism)
This category should be used when there is a severe and pervasive impairment in the development of reciprocal social interaction, verbal and nonverbal communication skills, or the development of stereotyped behavior, interests and Recreation, but the criteria are not met for a specific Pervasive Developmental Disorder, Schizophrenia, Schizotypal Personality Disorder, or Avoidant Personality Disorder.
 
Examples include:
Atypical autism: cases that do not meet the criteria for Autistic Disorder because of the late age onset, atypical symptomatology, or sub-threshold symptomatology, or all of these.