Brain Development and Disorders Project at MIT

Autism is a developmental disability which, most notably, impairs one’s ability to communicate and function socially. Autism is a Pervasive Developmental Disorders (PDD). It is a spectrum disorder, which means the symptoms can vary in severity. The characteristics of autism typically develop during the first three years of life.

Individuals with Autism tend to show a marked impairment in their social functioning, as well as communication. They may exhibit:

Rigid behavior including a resistance to change
Repetition of behavior and words
Difficulty using nonverbal communication (lack of appropriate eye contact, inability to read and utilize gestures or interpret body posture and facial expressions)
Total lack of or impairment of speech
Problems with imitative or spontaneous imaginative play considered typical of their peers
Perseveration on certain topics, categories or parts of objects
Engagement in repetitive motor movements.
They can also show a heightened sensitivity to their surroundings – smells, textures, sounds, etc.

Often times children with autism show large differences in different developmental categories – they may develop typically in one area (i.e., motor skills) but show a marked impairment in another (i.e., language acquisition).

Autism Spectrum Disorders affect between 2 and 6 per 1,000 people or 1 in 166 children, according to the Centers for Disease Control and Prevention (2004). Though the disorder affects all races, ethnicities and social groups alike, it is three-to-four times more likely to appear in boys than girls, according to the National Institute of Child Health and Human Development (2001).

Autism is diagnosed behaviorally using the guidelines set forth by the Diagnostic and Statistical Manual of Mental Disorders-IV-TR (2000) (DSM-IV).

There are a number of factors being researched as possible causes of autism. No one cause has been found to be directly linked to the occurrence of autism. Researchers are studying environmental and metabolic factors, infections and the possibility of genetic susceptibility involving multiple genes as possibly playing a role in the development of autism.

Though there is no “cure” for autism, there are multiple treatments which have proven to be successful including intensive education (the earlier the better) and certain medications (which may alleviate symptoms). It is important to remember the severity of the symptoms and the way in which autism presents vary greatly from person to person; for this reason some treatment approaches work for some, while they may not for others.

Autism is a Pervasive Developmental Disorders (PDD) along with Asperger’s Disorder, Childhood Disintegrative Disorder (CDD), Rett’s Disorder and PDD – Not Otherwise Specified (PDD-NOS).

Asperger’s Disorder manifests itself very similarly to autism; however, those with Asperger’s Disorder show no delay in language development. Obsessive, repetitive, rigid behavior, such as that seen with autism, is often apparent. A lack of ability to socially relate to peers is also persistent.

Childhood Disintegrative Disorder (CDD) is characterized by typical development through at least the first two years of life. Before the tenth year, the child begins to lose skill sets previously acquired. These can include language, ability to play, motor or social skills, etc.

Rett’s Disorder is characterized by a developmental regression, after typical development during at least the first five months of life. Prior to the fourth birthday (though most typically between one- and two-years-old) the child begins to regress in terms of motor skills (purposeful movements are replaced by incoordination and stereotypy) and language and head growth decelerates. Rett’s only develops in girls.

Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS) is a diagnosis used to describe a person who exhibits autistic symptoms but does not meet the criteria for the other four PDDs.

Fragile X is a disorder which is genetically inherited. It causes mental impairment as well as many classically autistic symptoms. Nearly one-third of children diagnosed with Fragile X also have autism (Hagerman). Fragile X is not listed in the DSM-IV.

American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision. Washington, DC, American Psychiatric Association, 2000.

Centers for Disease Control (2005). How common is Autism Spectrum Disorder (ASDs)? Retrieved February 23, 2006, from Centers for Disease Control and Prevention: Autism. Website: http://www.cdc.gov/ncbddd/autism/asd_common.htm

Hagerman, R. How do the behaviors seen in persons with Fragile X relate to those seen in autism? Retrieved February 23, 2006, from The National Fragile X Foundation: Autism. Website: http://www.fragilex.org/html/autism.htm

National Institute of Child Health and Human Development (2001). Facts about autism. Retrieved February 23, 2006, from National Institute of Child Health and Human Development: Health Information and Media – Publications. Website: http://www.nichd.nih.gov/publications/pubs/autism1.htm