Autism — Overview and Characteristics

This page preserves the original wording from the uploaded overview of autism and groups it for retrieval under a neutral section. Clearly labeled updates reflect current CDC/NIMH facts on terminology and prevalence.

Converted from DOCX • Grouped on 2025-09-24

Student Context

Update (2025-09-24): CDC monitoring data indicate an estimated about 1 in 31 8‑year‑old children identified with autism in 2022 across ADDM sites (not necessarily nationally representative). Boys are identified more often than girls. source

Update (2025-09-24): DSM‑5 (2013) replaced the older ‘pervasive developmental disorders’ (autistic disorder, Asperger disorder, CDD, PDD‑NOS) with a single diagnosis: autism spectrum disorder (ASD). Rett syndrome is no longer classified as ASD. source

Autism

General Overview

Information from the National Institute of Mental Health and the Center for Disease Control and Prevention (CDC) indicates that between 2 to 6 per 1,000 children (from 1 in 500 to 1 in 150) has some form of autism or pervasive developmental disorder (PDD). These disorders are four times more common in boys than in girls, although Rett’s Disorder has only been reported and diagnosed in girls. The causes of autism or PDD are unknown. Currently, researchers are investigating areas such as brain development, structure, genetic factors and biochemical imbalance in the brain as possible causes. These disorders are not caused by psychological factors. Children with autism/PDD vary widely in abilities, intelligence, and behaviors. Some children do not speak; other have language that often includes repeated phrases or conversations. Children with more advanced language skills tend to use a small range of topics and have difficulty with abstract concepts. Repetitive play skills, a limited range of interests, and impaired social skills are generally evident as well. Unusual responses to sensory information-for example, loud noises, lights, certain textures of food or fabrics- are also common. One of the distinguishing characteristics of children with Asperger’s syndrome is an observable developmental imbalance. On the one hand, they can be of average or superior intelligence; on the other, they are years behind in social development. Some or all of the following characteristics may be observed in mild to severe forms:

Communication problems (using and understanding language)

Difficulty relating to people, objects, and events

Unusual play with toys and other objects

Difficulty with changes in routine or familiar surroundings

Repetitive body movements or behavior patterns

Characteristics

Primary Communication: Deficits in verbal and nonverbal communication Examples include poor language skills, range of communication abilities (a small percentage are non-verbal, while some are competent communicators); limited eye contact; range of communication

Cognitive: Inadequate information processing Examples include problems in thinking skills such as problem solving, executive functioning, reasoning and evaluation, memory and classification; language skills

Emotional: Emotionally volatile Examples include high rates of behavioral problems such as tantrums, and self- stimulatory and aggressive behavior; resistant to environmental change or change in daily routines;

Social: Difficulties in social interaction Examples include need for adult guidance to attract and sustain social exchanges; lack of typical friendships and peer relationships affects motivation and the meaning of experiences; social isolation; memory and classification information in a social context is difficult; poor social skills

Sensory: Sensory integration dysfunction Examples include hyper and hyposensitivity to stimulation in the environment, and sensitivity to touch -

Secondary Motor: Functional motor skills difficulties Examples include gross, fine and motor planning difficulty; running and moving one’s body in a space; quality of movements can appear stiff or clumsy; weak motor skill response and motor imitation

References & Glossary