Childhood Disintegrative Disorder (CDD) refers to a disorder which is marked regression in multiple areas of functioning following a period of at least two years of apparently normal development.
It is a condition occurring in 3-4 year old children characterised by deterioration over several months of intellectual, social, and communicative functioning from previously normal behaviour.
With other words, it refers to pervasive developmental disorder involving severe regression in language, adaptive behavior, and motor skills after a 2- to 4-year period of normal development.