The Five Disorders on the Autism Spectrum

While the most recent edition of the DSM, the DSM-5, moved toward a unitary diagnosis for autism. Instead of defining several sub-diagnoses for autism such as Asperger’s or Rett Syndrome, the DSM regards autism as a single condition. Autistic advocacy organizations support this and view it as good for the community, as the old diagnoses had less to do with the individual and more to do with the non-autistic people around them. For many seeking understanding, recognizing the signs of autism in adults can be a crucial first step toward diagnosis and support. This change in the DSM has remained contentious since 2013. Whichever side of the debate a person falls on, though, it is important to recognize that the old sub-diagnoses are still commonly used and thus important to know.

The Five Autism Spectrum Disorders

Rett Syndrome

Rett Syndrome has often been regarded as an autism spectrum disorder and is perhaps the best example of the flaws in the old categorizations. Rett Syndrome is a genetic mutation that results in slowed brain and head growth, loss of hand control, trouble breathing, and other conditions. With regard to causes and internal experience, there isn’t much overlap between autism spectrum disorder and Rett Syndrome. Autism-related behaviors tend to only be present during a small window of the life of a girl with Rett, or in mild cases of the disorder.


Asperger’s refers to the idea of high-functioning autism, wherein an autistic person is outwardly able to work and participate in society seemingly without much trouble. This diagnosis may be a useful tool, but shouldn’t necessarily be taken at face value. Even if someone is able to work and care for themselves, this can hide issues such as executive function disorder and other invisible disabilities that fly under the radar. While Asperger’s persists in popular usage, autism advocacy organizations generally reject it and functioning labels altogether.

Pervasive Development Disorder Not Otherwise Specified

PDD-NOS might also be referred to as moderate-functioning autism. It served the role of filling a gap between Asperger’s and Autistic Disorder, a space for people that didn’t fully meet the criteria of either. If someone did not have the life skills and relative independence of a person with Asperger’s, it was common that they’d fall under PDD-NOS.

Autistic Disorder

Also known as low-functioning autism, Autistic Disorder diagnoses referred specifically to someone who couldn’t take care of themselves. In addition to severe problems with social and language skills, unusual and self-injurious behaviors are common.

Childhood Disintegrative Disorder

Childhood Disintegrative Disorder has traditionally been used to describe a child who followed standard trends of development at first. Then, between two and four years of age, the child experiences a rapid loss of language, social, and other skills. This loss of skills is irreversible, and it’s common that the child will also develop a seizure disorder.

Alter Behavioral Health Treats the Individual

Every person on the autism spectrum is different, and Alter appreciates this. Our priority isn’t applying or rejecting specific autism diagnoses, but understanding each patient and giving them the best care possible. If you or someone you know is an adult with autism, come to us to learn more about how we can help.