Autism Spectrum Disorder (ASD) is a neurodevelopmental condition that leads to characteristic differences in socialization and communication as well as characteristic behaviors (as defined by DSM-5). It is a spectrum disorder meaning that there is a highly varied set of symptoms among people with autism and varying degrees of severity.
Asperger’s syndrome used to be a separate diagnosis from autism, but has been brought under the umbrella of Autism Spectrum Disorder (ASD) in recent definitions of ASD in the DSM-5. Asperger’s tends to refer to people on the less severe side of the autism spectrum, and though the term is no longer used in health care settings, some people may still use it from time to time to describe more mild forms of autism.
The underlying biology in the brains of people with autism is not fully understood by researchers and scientists, and a single underlying process in the brain has not been found. The general consensus among scientists is that genetic factors cause changes in brain structure and connectivity, which in turn affects socialization and communication skills and causes the characteristic behaviors in people with autism. A significant amount of research time and funding is ongoing to better understand the biology of autism. We have additional details on the biology of autism and links to research in our new parent kit.
It’s important to note that the initial signs of autism in children can vary significantly for each child. Different children will often show different signs — some children may show many signs and other children may show few signs. The time course can also vary by child, with some children showing signs at a very young age (first few months of life), others showing signs after 1-2 years of life, and still other children appearing to have a normal development for their first couple of years and then appearing to regress and lose abilities they used to have (such as losing communication skills). And it is also possible to have some of the symptoms of autism but not have autism spectrum disorder. Because of this complexity, a specialized health care provider is needed to establish a diagnosis of autism.
The severity level is intended to capture the level of support and services required by a person with autism. The severity level can also change over time. The three levels are:
- Level 1: Requiring support
- Level 2: Requiring substantial support
- Level 3: Requiring very substantial support
The time course varies by child. Some children show signs at a very young age (first few months of life), others show signs after 1-2 years of life, and still other children appearing to have a normal development for their first couple of years and then appearing to regress and lose abilities they used to have (such as losing communication skills).
For the majority of people, autism is a lifelong condition. Said otherwise, children with autism become adults with autism. There are some reports of children who have received early intensive services and later no longer meet the diagnostic criteria of autism spectrum disorder. Such children may still need additional support (e.g., educational supports) relative to their neurotypical peers.
Autism is more common in boys. For instance, in Colorado, boys were 4.5 times as likely to be identified with autism than girls based on data from the CDC.