Childhood disintegrative disorder is a disease in the autism spectrum of conditions. It is characterized by either late delays in social and intellectual development, or a sudden and marked reversal of development. The onset is somewhat later than most forms of autism, coming at about the age of three. In many cases, the child is self aware of their decline and often questions his or her parents about the reversal.
In addition, there is disagreement about its treatment. Although therapy can be helpful, pharmaceuticals only treat the symptoms of the condition.