The two most common documents used for the diagnosis of Rett's disorder, Childhood Disintegrative disorder & PDD NOS are the DSM IV and ICD 10. The DSM IV is used mostly in the United States though it has been used elsewhere, including the U.K., whereas the ICD 10 is more commonly used in Europe. We have included the descriptions of both, as below.
DSM IV
Note: Consider a criterion met only if the behaviour is considerably more
frequent than that of most people of the same mental age.
DSM IV (Diagnostic & Statistical Manual) Diagnostic Criteria:
Rett's disorder
A. All of the following:
1. apparently normal prenatal and perinatal development
2. apparently normal psychomotor development through the first five months after birth
3. normal head circumference at birth
B. Onset of all of the following after the period of normal development:
1. deceleration of head growth between ages 5 and 48 months
2. loss of previously acquired purposeful hand skills between ages 5 and 30 months with the subsequent development of stereotyped hand movements (e.g., handwringing or handwashing)
3. loss of social engagement early in the course (although often social interaction develops later)
4. appearance of poorly coordinated gait or trunk movements
5. severely impaired expressive and receptive language development with severe psychomotor retardation
DSM IV (Diagnostic & Statistical Manual) Childhood disintegrative disorder Diagnostic Criteria:
Childhood disintegrative disorder
A. Apparently normal development for at least the first two years after birth as manifested by the presence of age-appropriate verbal and nonverbal communication, social relationships, play, and adaptive behavior
B. Clinically significant loss of previously acquired skills (before age 10 years) in at least two of the following areas:
1. expressive or receptive language
2. social skills or adaptive behavior
3. bowel or bladder control
4. play
5. motor skills
C. Abnormalities of functioning in at least two of the following areas:
1. qualitative impairment in social interaction (e.g., impairment in nonverbal behaviors, failure to develop peer relationships, lack of social or emotional reciprocity)
2. qualitative impairments in communication (e.g., delay or lack of spoken language, inability to initiate or sustain a conversation, stereotyped and repetitive use of language, lack of varied make-believe play)
3. restricted, repetitive, and stereotyped patterns of behavior, interests, and activities, including motor stereotypies and mannerisms)
D. The disturbance is not better accounted for by another specific pervasive developmental disorder or by schizophrenia.
DSM IV (Diagnostic & Statistical Manual) PDD NOS Diagnostic Criteria:
PDD NOS
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, schizotypal 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 at onset, atypical symptomatology, or subthreshold symptomatology, or all of these.