Prevalence
Epidemiological data are limited, but Childhood Disintegrative Disorder appears to be very rare and much less common than Autistic Disorder. Although initial studies suggested an equal sex ratio, the most recent data suggest that the condition is more common among males.
Course
By definition, Childhood Disintegrative Disorder can only be diagnosed if the symptoms are preceded by at least 2 years of normal development and the onset is prior to age 10 years. When the period of normal development has been quite prolonged (5 or more years), it is particularly important to conduct a thorough physical and neurological examination to assess for the presence of a general medical condition. In most cases, the onset is between ages 3 and 4 years and may be insidious or abrupt. Premonitory signs can include increased activity levels, irritability, and anxiety followed by a loss of speech and other skills. Usually the loss of skills reaches a plateau, after which some limited improvement may occur, although improvement is rarely marked. In other instances, especially when the disorder is associated with a progressive neurological condition, the loss of skills is progressive. This disorder follows a continuous course, and in the majority of cases the duration is lifelong. The social, communicative, and behavioral difficulties remain relatively constant throughout life.
Differential Diagnosis
Periods of regression may be observed in normal development, but these are neither as severe nor as prolonged as in Childhood Disintegrative Disorder. Childhood Disintegrative Disorder must be differentiated from other Pervasive Developmental Disorders. For the differential diagnosis with Autistic Disorder, see Autistic Disorder. For the differential diagnosis with Rett's Disorder, see Rett's Disorder. In contrast to Asperger's Disorder, Childhood Disintegrative Disorder is characterized by a clinically significant loss in previously acquired skills and a greater likelihood of Mental Retardation. In Asperger's Disorder, there is no delay in language development and no marked loss of developmental skills.
Childhood Disintegrative Disorder must be differentiated from a dementia with onset during infancy or childhood. Dementia occurs as a consequence of the direct physiological effects of a general medical condition (e.g., head trauma), whereas Childhood Disintegrative Disorder typically occurs in the absence of an associated general medical condition.
(299.10 Childhood Disintegrative Disorder from the Diagnostic and Statistical Manual of Mental Disorders: DSM IV)
