Which disorder is associated with loss of language, social, and motor skills that begins after normal development?

Childhood Disintegrative Disorder is characterized by a significant regression in language, social, and motor skills after a period of normal development. Typically, children develop normally for the first 2 to 4 years of life, but then they experience a marked decline in these areas. This disorder appears to be distinct from other autism spectrum disorders, as it involves a more dramatic loss of previously acquired skills rather than atypical development from the outset.

In contrast, autism and Asperger's Disorder are characterized by developmental abnormalities that are present from early childhood, rather than a loss of skills after a normal period. Conversion Disorder involves neurological symptoms that cannot be fully explained by a medical condition, and does not inherently involve regression of previously acquired skills. Thus, Childhood Disintegrative Disorder is the appropriate diagnosis due to the specific timeline and nature of skill loss following a period of normal development.