What is autism?

Autism Spectrum Disorder (ASD) is group of complex disorders that affect brain development. ASD is typically associated with difficulties in the following areas:

  • Social communication
  • Social interaction
  • Restricted, repetitive patterns of behavior, interests or activities

Autism can also be associated with intellectual disabilities, delay or absence of language development, trouble with motor coordination and/or attention, and physical health issues.

More about autism

ASD occurs during the early brain developmental stages. However, the behavioral signs of autism surface between the ages of two or three. Individuals with ASD have difficulties with social interaction as well as problems with interpreting and using non-verbal and verbal communication in social contexts. Individuals with ASD also have at least two of the following behavioral difficulties:

  • Inflexible interests
  • Insistence on sameness in environment or routine
  • Repetitive motor and sensory behaviors
  • Increased or decreased reactions to sensory stimuli

The severity of these behaviors typically ranges from mild to severe and results in functional impairments. These impairments range from requiring some supports to requiring very intense supports. Given that autism varies widely in its symptoms, severity and functional impairment, some individuals can have their symptoms go unrecognized.

How common is autism?

  • ASD affects 1 in 68 children
  • It affects 1 in 42 boys
  • It affects 1 in 189 girls
  • Boys are nearly 5 times more likely to have ASD than girls
  • Government autism statistics suggest that prevalence rates have increased 10 to 17 percent annually in recent years

What causes autism?

Several decades of scientific evidence supports a strong genetic component to ASD. However, at present, specific genetic causes can only be identified in 10-20% of cases. These cases include specific genetic syndromes associated with ASD and rare changes in the genetic code. The identification of genetic contributions to ASD is likely to increase in the future as technologies for identifying very small genetic changes and linking them to ASD improve. The only other well-established risk factors for ASD are advanced paternal age and low birth weight/prematurity.

What are the signs of autism?

Autism signs range in severity from mild to disabling. Every child is different. However, the following are considered to be red flags that indicate your child is at risk for autism. If your child shows any of these signs, please do not hesitate to contact a physician and ask for an evaluation:

  • Inconsistent or absent responding when the child’s name is called
  • No big smiles or warm, joyful expressions by six months or after
  • No back-and-forth sharing of smiles, sounds and other facial expressions by nine months
  • No babbling by 12 months
  • No back-and-forth gestures such as showing, pointing, reaching or waving by 12 months
  • No words by 16 months
  • No meaningful, two-word phrases (not including imitating or repeating) by 24 months
  • Any loss of speech, babbling or social skills at any age

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy