What Causes Autism?
There is no known single cause for autism spectrum disorder, but it is generally accepted that it is caused by abnormalities in brain structure or function. Brain scans show differences in the shape and structure of the brain in children with autism compared to in neurotypical children.
Researchers do not know the exact cause of autism but are investigating a number of theories, including the links among heredity, genetics and medical problems. In many families, there appears to be a pattern of autism or related disabilities, further supporting the theory that the disorder has a genetic basis. While no one gene has been identified as causing autism, researchers are searching for irregular segments of genetic code that children with autism may have inherited.
It also appears that some children are born with a susceptibility to autism, but researchers have not yet identified a single trigger that causes autism to develop. Other researchers are investigating the possibility that under certain conditions, a cluster of unstable genes may interfere with brain development, resulting in autism. Still other researchers are investigating problems during pregnancy or delivery as well as environmental factors such as viral infections, metabolic imbalances and exposure to chemicals.
Autism tends to occur more frequently than expected among individuals who have certain medical conditions, including fragile X syndrome, tuberous sclerosis, congenital rubella syndrome and untreated phenylketonuria (PKU). Some harmful substances ingested during pregnancy also have been associated with an increased risk of autism.
Some Facts & Statistics about Autism!
Learn the signs: Early identification can change lives
The characteristic behaviors of autism spectrum disorder may be apparent in infancy (18 to 24 months), but they usually become clearer during early childhood (24 months to 6 years).
As part of a well-baby or well-child visit, your childs doctor should perform a developmental screening, asking specific questions about your baby’s progress. The National Institute of ChildHealth and Human Development (NICHD) lists five behaviors that warrant further evaluation:
- Does not babble or coo by 12 months
- Does not gesture (point, wave, grasp) by 12 months
- Does not say single words by 16 months
- Does not say two-word phrases on his or her own by 24 months
- Has any loss of any language or social skill at any age
Any of these five red flags does not mean your child has autism. But because the disorders symptoms vary so widely, a child showing these behaviors should be evaluated by a multidisciplinary team. This team might include a neurologist, psychologist, developmental pediatrician, speech/language therapist, learning consultant or other professionals who are knowledgeable about autism.
When parents or support providers become concerned that their child is not following a typical developmental course, they turn to experts, including psychologists, educators and medical professionals, for a diagnosis.
At first glance, some people with autism may appear to have an intellectual disability, sensory processing issues, or problems with hearing or vision. To complicate matters further, these conditions can co-occur with autism. However, it is important to distinguish autism from other conditions, as an accurate and early autism diagnosis can provide the basis for an appropriate educational and treatment program.
Other medical conditions or syndromes, such as sensory processing disorder, can present symptoms that are confusingly similar to autism’s. This is known as differential diagnosis. There are many differences between a medical diagnosis and an educational determination, or school evaluation, of a disability. A medical diagnosis is made by a physician based on an assessment of symptoms and diagnostic tests. A medical diagnosis of autism spectrum disorder, for instance, is most frequently made by a physician according to the Diagnostic and Statistical Manual (DSM-5, released 2013) of the American Psychological Association.
This manual guides physicians in diagnosing autism spectrum disorder according to a specific number of symptoms. A brief observation in a single setting cannot present a true picture of someones abilities and behaviors. The persons developmental history and input from parents, caregivers and/or teachers are important components of an accurate diagnosis. An educational determination is made by a multidisciplinary evaluation team of various school professionals. The evaluation results are reviewed by a team of qualified professionals and the parents to determine whether a student qualifies for special education and related services under the Individuals with Disabilities Education Act (IDEA) (Hawkins, 2009).