Pervasive Development Disorders (PDD)
The term “PDD” is widely used by professionals to refer to children with autism and related disorders; however, there is a great deal of disagreement and confusion among professionals concerning the PDD label. Diagnosis of PDD, including autism or any other developmental disability, is based upon the Diagnostic and Statistical Manual of Mental Disorders – Fourth Edition (DSM-IV), published by the American Psychiatric Association (Washington, DC, 1994), and is the main diagnostic reference of mental health professionals in the U.S.
According to the DSM-IV, the term “PDD” is not a specific diagnosis, but an umbrella term under which the specific diagnoses are defined.
Diagnostic labels are used to indicate commonalities among individuals. The key defining symptom of autism that differentiates it from other syndromes and/or conditions is substantial impairment in social interaction (Frith, 1989). The diagnosis of autism indicates that qualitative impairments in communication, social skills, and range of interests and activities exist. As no medical tests can be performed to indicate the presence of autism or any other PDD, the diagnosis is based upon the presence or absence of specific behaviors. For example, a child may be diagnosed as having PDD-NOS if he or she has some behaviors that are seen in autism, but does not meet the full criteria for having autism. Most importantly, whether a child is diagnosed with a PDD (like autism) or a PDD-NOS, his/her treatment will be similar.
Autism is a spectrum disorder, with symptoms ranging from mild to severe. As a spectrum disorder, the level of developmental delay is unique to each individual. If a diagnosis of PDD-NOS is made, rather than autism, the diagnosticians should clearly specify the behaviors present. Evaluation reports are more useful if they are specific and become more helpful for parents and professionals in later years when reevaluations are conducted.
Ideally, a multidisciplinary team of professionals should evaluate a child suspected of having autism. The team may include, but may not be limited to, a psychologist or psychiatrist, a speech pathologist and other medical professionals, including a developmental pediatrician and/or neurologist. Parents and teachers should also be included, as they have important information to share when determining a child’s diagnosis.
In the end, parents should be more concerned that their child find the appropriate educational treatment based on their needs, rather than spending too much effort to find the perfect diagnostic label. Most often, programs designed specifically for children with autism will produce greater benefits, while the use of the general PDD label can prevent children from obtaining services relative to their needs.
Also within each diagnosis is the Autism Society’s Panel of Professional Advisors’ recommended definition of the autism spectrum and related syndromes and conditions, which is not to be used for research purposes but rather for defining the demographics of the Autism Society’s membership. The Autism Society is not attempting to represent individuals with related syndromes or conditions who do not also have autism, but rather those where autism is present in related syndromes and conditions, and where autism is the defining syndrome (e.g., autism-Asperger’s). The rationale for this position is due to the unique service needs that are imperative for individuals with autism that may not be required of the cohort disability.
Autistic Disorder (299.00 DSM-IV)
The central features of Autistic Disorder are the presence of markedly abnormal or impaired development in social interaction and communication, and a markedly restricted repertoire of activity and interest. The manifestations of this disorder vary greatly depending on the developmental level and chronological age of the individual. Autistic Disorder is sometimes referred to as Early Infantile Autism, Childhood Autism, or Kanner’s Autism (page 66).
Asperger’s Disorder (299.80 DSM-IV)
The essential features of Asperger’s Disorder are severe and sustained impairment in social interaction and the development of restricted, repetitive patterns of behavior, interest, and activity. The disturbance must clinically show significant impairment in social, occupational, and other important areas of functioning. In contrast to Autistic Disorder, there are no clinically significant delays in language. In addition there are no clinically significant delays in cognitive development or in the development of age-appropriate self-help skills, adaptive behavior, and curiosity about the environment in childhood.
Rett’s Disorder (299.80 DSM-IV)
The essential feature of Rett’s Disorder is the development of multiple specific deficits following a period of normal functioning after birth. There is a loss of previously acquired purposeful hand skills before subsequent development of characteristic hand movement resembling hand wringing or hand washing. Interest in the social environment diminishes in the first few years after the onset of the disorder. There is also significant impairment in expressive and receptive language development with severe psychomotor retardation. (Page 71)
Childhood Disintegrative Disorder (299.10 DSM-IV)
The central feature of Childhood Disintegrative Disorder is a marked regression in multiple areas of functioning following a period of at least two years of apparently normal development. After the first two years of life, the child has a clinically significant loss of previously acquired skills in at least two of the following areas: expressive or receptive language; social skills or adaptive behavior; bowel or bladder control; or play or motor skills. Individuals with this disorder exhibit the social and communicative deficits and behavioral features generally observed in Autistic Disorder, as there is qualitative impairment in social interaction, communication, and restrictive, repetitive and stereotyped patterns of behavior, interests, and activities. (Page 73)
PDD-NOS (299.80 DSM-IV)
The essential features of PDD-NOS are severe and pervasive impairment in the development of reciprocal social interaction or verbal and nonverbal communication skills; and stereotyped behaviors, interests, and activities. The criteria for Autistic Disorder are not met because of late age onset; atypical and/or sub- threshold symptomotology are present. (Page 77-78)
This category should be used when there is a severe and pervasive impairment in the development of reciprocal 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, Schizotypical Personality Disorder, or Avoidant Personality Disorder. For example, this category includes “atypical autism“– presentations that do not meet the criteria for Autistic Disorder because of late age of onset, atypical symptomatology, or sub-threshold symptomatology, or all of these.