Autism spectrum disorder includes conditions previously called autism, pervasive developmental disorder, and Asperger’s syndrome. The causes are not known.
The severity of symptoms varies greatly, but all people with autism have some core symptoms in the areas of:
Social interactions and relationships. Symptoms may include:
Significant problems developing nonverbal communication skills, such as eye-to-eye gazing, facial expressions, and body posture.
Failure to establish friendships with children the same age.
Lack of interest in sharing enjoyment, interests, or achievements with other people.
Lack of empathy. People with autism may have difficulty understanding another person’s feelings, such as pain or sorrow.
Verbal and nonverbal communication. Symptoms may include:
Delay in, or lack of, learning to talk. As many as 40% of people with autism never speak.1
Problems taking steps to start a conversation. Also, people with autism have difficulties continuing a conversation after it has begun.
Stereotyped and repetitive use of language. People with autism often repeat over and over a phrase they have heard previously (echolalia).
Difficulty understanding their listener’s perspective. For example, a person with autism may not understand that someone is using humor. They may interpret the communication word for word and fail to catch the implied meaning.
Limited interests in activities or play. Symptoms may include:
An unusual focus on pieces. Younger children with autism often focus on parts of toys, such as the wheels on a car, rather than playing with the entire toy.
Preoccupation with certain topics. For example, older children and adults may be fascinated by video games, trading cards, or license plates.
A need for sameness and routines. For example, a child with autism may always need to eat bread before salad and insist on driving the same route every day to school.
Stereotyped behaviors. These may include body rocking and hand flapping.
Symptoms during childhood
Symptoms of autism are usually noticed first by parents and other caregivers sometime during the child’s first 3 years. Although autism is present at birth (congenital), signs of the disorder can be difficult to identify or diagnose during infancy. Parents often become concerned when their toddler does not like to be held; does not seem interested in playing certain games, such as peekaboo; and does not begin to talk. Sometimes, a child with autism will start to talk at the same time as other children the same age, then lose his or her language skills. Parents also may be confused about their child’s hearing abilities. It often seems that a child with autism does not hear, yet at other times, he or she may appear to hear a distant background noise, such as the whistle of a train.
With early and intensive treatment, most children improve their ability to relate to others, communicate, and help themselves as they grow older. Contrary to popular myths about children with autism, very few are completely socially isolated or “live in a world of their own.”
Symptoms during teen years
During the teen years, the patterns of behavior often change. Many teens gain skills but still lag behind in their ability to relate to and understand others. Puberty and emerging sexuality may be more difficult for teens who have autism than for others this age. Teens are at an increased risk for developing problems related to depression, anxiety, and epilepsy.
Symptoms in adulthood
Some adults with autism are able to work and live on their own. The degree to which an adult with autism can lead an independent life is related to intelligence and ability to communicate. At least 33% are able to achieve at least partial independence.2
Some adults with autism need a lot of assistance, especially those with low intelligence who are unable to speak. Part- or full-time supervision can be provided by residential treatment programs. At the other end of the spectrum, adults with high-functioning autism are often successful in their professions and able to live independently, although they typically continue to have some difficulties relating to other people. These individuals usually have average to above-average intelligence.
Many people with autism have symptoms similar to attention deficit hyperactivity disorder (ADHD). But these symptoms, especially problems with social relationships, are more severe for people with autism.
About 10% of people with autism have some form of savant skills—special limited gifts such as memorizing lists, calculating calendar dates, drawing, or musical ability.
Many people with autism have unusual sensory perceptions. For example, they may describe a light touch as painful and deep pressure as providing a calming feeling. Others may not feel pain at all. Some people with autism have strong food likes and dislikes and unusual preoccupations.
Sleep problems occur in about 40% to 70% of people with autism.
Almost half of the children who have autism spectrum disorders tend to “wander off” from a caregiver, or “elope.” For many caregivers of these children, elopement is one of the most stressful behaviors they must learn to cope with. Studies show that behavioral assessment interventions, such as applied behavioral analysis, may reduce the number of times a child wanders off.
Autism is one of several types of autism spectrum disorders (ASDs), once known as pervasive developmental disorders. It is not unusual for autism to be confused with other ASDs, such as Asperger’s syndrome, or to have overlapping symptoms. A similar condition is called unspecified neurodevelopmental disorder. This condition occurs when children display similar behaviors but do not meet the criteria for autism. Also, other conditions with similar symptoms may also have similarities to or occur with autism.
Risk Factors and Characteristics
- Studies have shown that among identical twins, if one child has ASD, then the other will be affected about 36-95% of the time. In non-identical twins, if one child has ASD, then the other is affected about 0-31% of the time. [1-4]
- Parents who have a child with ASD have a 2%–18% chance of having a second child who is also affected.[5,6]
- ASD tends to occur more often in people who have certain genetic or chromosomal conditions. About 10% of children with autism are also identified as having Down syndrome, fragile X syndrome, tuberous sclerosis, or other genetic and chromosomal disorders.[7-10]
- Almost half (46%) of children identified with ASD has average to above average intellectual ability. [Read article]
Most recent intelligence quotient (IQ) as of age 8 years among children identified with autism spectrum disorder (ASD) for whom test data were available,* by site and sex- Autism and Developmental Disabilities Monitoring Network, seven sites†, United States, 2010
- Children born to older parents are at a higher risk for having ASD. [Read summary]
- A small percentage of children who are born prematurely or with low birth weight are at greater risk for having ASD. [Read summary]
- ASD commonly co-occurs with other developmental, psychiatric, neurologic, chromosomal, and genetic diagnoses. The co-occurrence of one or more non-ASD developmental diagnoses is 83%. The co-occurrence of one or more psychiatric diagnoses is 10%. [Read summary]
- Research has shown that a diagnosis of autism at age 2 can be reliable, valid, and stable. [Read summary] [Read summary]
- On average, children identified with ASD were not diagnosed until after age 4, even though children can be diagnosed as early as age 2. When looking at age of first diagnosis by subtype, on average, those children were diagnosed with Autistic Disorder at age 4, Pervasive Developmental Disorder-Not Otherwise Specified at age 4 years and 2 months, and Asperger Disorder at age 6 years and 2 months. [Read article]
- Studies have shown that parents of children with ASD notice a developmental problem before their child’s first birthday. Concerns about vision and hearing were more often reported in the first year, and differences in social, communication, and fine motor skills were evident from 6 months of age.[Read summary] [Read summary]
- It is estimated to cost at least $17,000 more per year to care for a child with ASD compared to a child without ASD. Costs include health care, education, ASD-related therapy, family-coordinated services, and caregiver time. For a child with more severe ASD, costs per year increase to over $21,000. Taken together, it is estimated that total societal costs of caring for children with ASD were over $9 billion in 2011. [Read article]
- Children and adolescents with ASD had average medical expenditures that exceeded those without ASD by $4,110–$6,200 per year. On average, medical expenditures for children and adolescents with ASD were 4.1–6.2 times greater than for those without ASD. Differences in median expenditures ranged from $2,240 to $3,360 per year with median expenditures 8.4–9.5 times greater. [Read article]
- In 2005, the average annual medical costs for Medicaid-enrolled children with ASD were $10,709 per child, which was about six times higher than costs for children without ASD ($1,812). [Read summary]
- In addition to medical costs, intensive behavioral interventions for children with ASD cost $40,000 to $60,000 per child per year.
- Rosenberg RE, Law JK, Yenokyan G, McGready J, Kaufmann WE, Law PA. Characterisitics and concordance of autism spectrum disorders among 277 twin pairs. Arch Pediatr Adolesc Med. 2009; 163(10): 907-914.
- Hallmayer J, Cleveland S, Torres A, Phillips J, Cohen B, Torigoe T, Miller J, Fedele A, Collins J, Smith K, Lotspeich L, Croen LA, Ozonoff S, Lajonchere C, Grether JK, Risch N. Genetic heritability and shared environmental factors among twin pairs with autism. Arch Gen Psychiatry. 2011; 68(11): 1095-1102.
- Ronald A, Happe F, Bolton P, Butcher LM, Price TS, Wheelwright S, Baron-Cohen S, Plomin R. Genetic heterogeneity between the three components of the autism spectrum: A twin study. J. Am. Acad. Child Adolesc. Psychiatry. 2006; 45(6): 691-699.
- Taniai H, Nishiyama T, Miyahci T, Imaeda M, Sumi S. Genetic influences on the board spectrum of autism: Study of proband-ascertained twins. Am J Med Genet B Neuropsychiatr Genet. 2008; 147B(6): 844-849.
- Ozonoff S, Young GS, Carter A, Messinger D, Yirmiya N, Zwaigenbaum L, Bryson S, Carver LJ, Constantino JN, Dobkins K, Hutman T, Iverson JM, Landa R, Rogers SJ, Sigman M, Stone WL. Recurrence risk for autism spectrum disorders: A Baby Siblings Research Consortium study. Pediatrics. 2011; 128: e488-e495.
- Sumi S, Taniai H, Miyachi T, Tanemura M. Sibling risk of pervasive developmental disorder estimated by means of an epidemiologic survey in Nagoya, Japan. J Hum Genet. 2006; 51: 518-522.
- DiGuiseppi C, Hepburn S, Davis JM, Fidler DJ, Hartway S, Lee NR, Miller L, Ruttenber M, Robinson C. Screening for autism spectrum disorders in children with Down syndrome. J Dev Behav Pediatr. 2010; 31:181-191.
- Cohen D, Pichard N, Tordjman S, Baumann C, Burglen L, Excoffier E, Lazar G, Mazet P, Pinquier C, Verloes A, Heron D. Specific genetic disorders and autism: Clinical contribution towards their identification. J Autism Dev Disord. 2005; 35(1): 103-116.
- Hall SS, Lightbody AA, Reiss AL. Compulsive, self-injurious, and autistic behavior in children and adolescents with fragile X syndrome. Am J Ment Retard. 2008; 113(1): 44-53.
- Zecavati N, Spence SJ. Neurometabolic disorders and dysfunction in autism spectrum disorders. Curr Neurol Neurosci Rep. 2009; 9(2): 129-136.
- Amendah, D., Grosse, S.D., Peacock, G., & Mandell, D.S. (2011). The economic costs of autism: A review. In D. Amaral, D. Geschwind, & G. Dawson (Eds.), Autism spectrum disorders (pp. 1347-1360). Oxford: Oxford University Press.