Autism spectrum disorder has not always been a singular diagnosis; before 2013, what is now classified as autism spectrum disorder encompassed five separate conditions, all of which had their own definitions.
Now known as level 1 autism spectrum disorder, this disorder is still commonly referred to as Asperger’s. Someone with level 1 ASD will be highly intelligent and might also have strong verbal skills, but they will exhibit issues with social interactions. Characteristics they might display include behavioral inflexibility, challenges with executive functioning, and difficulty with managing speech.
Nowadays, this is recognized as a genetic condition and is no longer considered an autism spectrum disorder. It mostly affects girls, and it presents challenges to almost every aspect of a child’s life. It is characterized by loss of movement and coordination, challenges with communication and speech, and sometimes breathing difficulties.
Childhood Disintegrative Disorder (CDD)
Also known as disintegrative psychosis, this disorder is defined by the delayed onset of developmental problems; a child will experience normal development, then suddenly hit a snag. The cause of CDD is unknown but is thought to be neurobiological; it affects boys more than girls.
Kanner’s Syndrome is what is referred to as “classic” autism; the doctor who discovered it, Leo Kanner, originally characterized it as infantile autism. Children diagnosed with this syndrome are said to appear alert and intelligent while also displaying characteristics like lack of emotional attachment, uncontrolled speech, and challenges with communication and interaction.
Pervasive Developmental Disorder- Not Otherwise Specified
Usually shortened as PDD-NOS, this disorder presents a range of symptoms; the most common ones are difficulties in social and language development. A child with this diagnosis might present with delays in language and motor skills development; the disorder is then identified through observation. It has also been referred to as “subthreshold autism.”