Autism spectrum disorders include social, behavioral and communication challenges . These problems can be mild, severe or moderate. Early diagnosis is important, because early treatment can make a big difference.

What are the types of disorders on the autistic spectrum?

Until recently, experts talked about different  types of autism , such as autistic disorder, Asperger’s syndrome, non-specified invasive developmental disorder (PDD-NOS). But now they are all called “autism spectrum disorders.”

Of course, you will continue to hear people use some of the older terms, and you may want to know what they mean:

Asperger’s syndrome. This disorder is at the milder end of the autism spectrum. A person with Asperger’s can be very intelligent and able to handle his daily life. She can really focus on topics of interest and discuss them over and over. But she has some difficulty in social life.

Invasive developmental disorders, not otherwise specified (PDD-NOS). This diagnosis includes most children whose autism is more severe than Asperger’s syndrome, but not as severe as autistic disorder.

Autistic disorder. This older term is further along the autism spectrum than Asperger and PDD-NOS. It includes the same types of symptoms, but at a more intense level.

Childhood disintegrative disorder. This was the rarest and most serious part of the spectrum. It describes children who develop normally, but quickly lose many social, language and mental skills, usually between the ages of 2 and 4 years.

Is Rett syndrome an autism spectrum disorder?

Children with Rett syndrome often behave similarly to children with autism, and it was grouped by experts among ASDs. But now that we know it is caused by a genetic mutation, it is no longer considered an autism spectrum disorder.