Pervasive developmental disorders are comes under socio emotional disorder. A heterogeneous collection of disorders affecting young children’s social interaction and ability to communicate, commonly combined with stereotyped behavioral patterns. The severe form of pervasive developmental disorders is autism spectrum disorders.
The term "Autism Spectrum Disorders" refers to a range of neurological disorders that affect a child's ability to communicate, relate to others and understand or respond to sensory input. In general, the cause of these disorders is not known. Autism spectrum disorders affect each child in a unique way.
The term autistic spectrum disorder (ASD) is an umbrella term that encompasses the terms autism, Asperger’s syndrome (also known as high functioning autism), autistic disorder and classic autism (also known as Kanner’s autism). Autism spectrum disorders (ASD) are developmental disorders that include a wide range of symptoms and are classified into three main categories:
Pervasive developmental disorder (PDD-NOS)
The child has marked impairment in social relatedness and shows repetitive and stereotype patterns of behavior without delay in language development.
Rett’s disorder occurs exclusively in girls, it is characterized by normal development for at least 6 months, stereotyped hand movement, loss of purposeful motions, decreasing social engagement, decreasingly language use.
Childhood disintegrative disorder
Childhood disintegrative disorder, development is normal up to first 2 years of age, after which there is loss of previously acquired skills either in language use, social responsiveness, play motor skills, bladder and bowel control.