Autism is a complex neurodevelopmental condition that affects how a person communicates with and relates to other people, and how they experience the world around them. Autism is considered a “spectrum” disorder because there is wide variation in the type and severity of symptoms people experience. There is no single known cause of autism, but research suggests that autism develops from a combination of genetic and environmental factors that influence early brain development.
What is autism?
Autism spectrum disorder (ASD) is characterized by challenges with social communication and interaction, and restricted or repetitive behaviors and interests. People with autism have differences in how they engage socially, communicate verbally and nonverbally, play, learn, focus their attention, and engage in repetitive behaviors or interests.
The most obvious signs of autism usually appear between ages 2 and 3. Some associated developmental concerns may begin to appear earlier, while others may not become evident until a child is of school age. The diagnosis of autism requires an evaluation by a team of doctors and mental health professionals.
ASD occurs in all racial, ethnic, and socioeconomic groups but is 4-5 times more common in boys than in girls. The Centers for Disease Control and Prevention (CDC) estimates that about 1 in 44 children has been diagnosed with ASD as of 2018, up from 1 in 59 in 2014.
Key characteristics of autism
- Difficulties with social communication and interaction, including problems understanding nonverbal cues, failure to develop age-appropriate peer relationships, and lack of shared interests.
- Restricted, repetitive patterns of behavior, interests, or activities such as repetitive body movements, rigid adherence to routines, highly restricted interests, and hyper- or hypo-reactivity to sensory input.
- Symptoms that are present in early childhood development, usually before age 3.
- Symptoms that cause significant impairment in important areas of functioning.
The severity of autism symptoms varies widely across individuals, which is why it is called a “spectrum” disorder. Some people have mild symptoms while others have more substantial challenges with communication and behavior. But all people with ASD have some degree of difficulty with social communication, social interaction, and restricted or repetitive behaviors or interests.
What causes autism?
There is no single known cause of autism. Research suggests that autism develops from a combination of genetic and environmental factors that influence early brain development. It is not caused by anything that a parent did or did not do.
Genetic factors
ASD has a strong genetic basis, although no single gene has been directly linked as a cause. Studies of identical twins suggest that if one twin has autism, the other twin 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.
Several gene changes or mutations appear to be associated with autism risk. These DNA differences disrupt early brain development and lead to the characteristic signs of autism. In about 10-20% cases, autism is associated with a genetic syndrome such as fragile X syndrome, tuberous sclerosis, or Rett syndrome.
Environmental risk factors
Research also suggests that certain environmental influences may raise the risk of autism, particularly if they occur during pregnancy. These may include:
- Advanced parental age at conception
- Pregnancy complications that result in oxygen deprivation to the baby’s brain
- Exposure to air pollution or certain pesticides during pregnancy
- Viral infections such as rubella or cytomegalovirus during pregnancy
- High levels of inflammation during pregnancy
However, the involvement of most of these factors in raising autism risk is still unclear and more research is needed. The most consistent risk factor identified is advanced parental age, especially in fathers over age 50.
Why are more kids being diagnosed with autism?
The number of children diagnosed with ASD has increased dramatically since the 1990s. For example, data from the CDC indicates that less than 1 in 150 U.S. children were identified with autism in 2000, compared to 1 in 44 today.
However, it is unclear how much of this rise is real and how much is due to increased awareness and expanded diagnostic criteria for autism. Here are some of the factors that may contribute to rising autism rates:
Expanded diagnostic criteria
In 2013, the American Psychiatric Association expanded the diagnostic criteria for autism. Asperger’s syndrome and other disorders were folded into the broad category of autism spectrum disorder. The new diagnoses likely captured some individuals who would not previously have been identified.
Better awareness
Over the last few decades, public understanding and medical expertise related to autism have improved substantially. Parents and doctors are more attuned to early signs of ASD, leading to earlier diagnosis.
Increased access to services
Federal legislation mandating early intervention for children with disabilities has led to greater access to assessment. More parents are motivated to seek help for concerns about their child’s development.
Older parental age
Advanced parental age has been linked to increased autism risk. Over the last several decades, more people have been delaying childbearing into their 30s and 40s. Some of the rising prevalence could be linked to older parents.
Unknown environmental triggers
While research is not conclusive yet, some increase in autism may be due to as-yet-unidentified environmental risk factors. These could include maternal infections or inflammation, medications, or toxic exposures in genetically susceptible individuals.
Can autism be cured?
There is no “cure” for autism. It is a lifelong neurodevelopmental disorder that manifests early in childhood but persists over an individual’s lifetime. However, behavioral treatments and medications can help manage symptoms and improve quality of life for people with autism.
With early intervention and ongoing support, many children with autism can gain important skills, such as:
- Improved communication and social skills
- Greater independence in activities of daily living
- Decreased disruptive behaviors
- Enhanced school performance
- Successful transition to adulthood
Treatment may involve behavioral therapies, speech and occupational therapy, specialized educational support, parent education, medications, and assistance with activities of daily living when needed.
While autism cannot be cured, therapy and support services allow many people with ASD to live fulfilling, productive lives within their communities.
Conclusion
In summary, autism arises from a complex combination of genetic and environmental influences that affect early brain development. There is no single cause. While autism rates have increased sharply in recent decades, it is unclear how much of this rise is real versus increased awareness and changing diagnostic practices. There is no medical cure for autism, but early intervention, behavioral and educational therapies, and support services allow people with autism to maximize their potential and lead meaningful lives.