Researchers at the Texas A&M University School of Medicine and School of Veterinary Medicine and…
It is a mental disorder, but understanding autism can really tax your brain
Autism is complicated. Its definition is complicated. Its cause is complicated. Its diagnosis is complicated. Its treatment is complicated. But two autism researchers will try to simplify it for you.
What people refer to as “autism” is actually any one of a number of mental disorders that can make it challenging for a person to communicate with, relate to, or behave in a “typical” manner around other people. “Autism is a rather subjective phenotype that relates to an individual’s behavioral challenges, which are difficult to measure,” said Vytas A. Bankaitis, PhD, the E.L. Wehner-Welch Foundation Chair in Chemistry at the Texas A&M College of Medicine.
Indeed, autism is not just one disorder. “It presents itself as a number of conditions collectively known as autism spectrum disorders (ASDs), which affect about one in every 68 children, with five times as many males than females being diagnosed,” said Zhigang Xie, PhD, assistant research scientist at the Texas A&M College of Medicine.
Some with autism are able to live and function in the professional world, while others will require life-long assistance. However, the personal impacts of living with autism are not the only obstacles. “The social costs of ASDs are huge,” Bankaitis said. “The estimate is that by year 2025, in the United States alone, ASDs could cost about half a trillion dollars per year.” The economic costs were approximately $265 billion in 2015.
The cause of autism has not yet been determined, but it is important to note that researchers agree that the best available evidence indicates that vaccines have shown no evidence of causing autism.
The neocortex in the brain is made up of billions of neurons that have to make their correct contacts to function properly. Like any complicated machine, subtle defects can change how the machine works. “Each human has their unique behavior, and that reflects the wiring of the brain,” Bankaitis said. “If certain wiring differences are amplified, then you can get abnormal behaviors.”
Autism does run in families, so there is a genetic link to it. There are about 30 genes currently associated with autism. This is only a small fraction of the likely total—some estimate that up to 1000 genes may be eventually linked to autism, according to Bankaitis. For most cases, there is no currently available genetic test that can give parents accurate information that forecasts autism risk because the genetics associated with autism risk are complex.
Researchers are still looking into environmental contributors to ASDs, and it is becoming increasingly clear that environmental factors will play significant roles. The health of the mother, fetal oxygen supply during birth or injuries are thought to potentially induce autism, but they will not always lead to autism in every child.
In fact, Xie is the lead author of a study that found that an insufficient amount of an already-available dietary supplement could protect against autism in some cases. By developing technology to manipulate neural stem cells in the brain during embryotic development, his research with Bankaitis shows that carnitine, which is responsible for metabolism of fatty acids, can negate autism risks associated with a known autism gene called TMLHE. This gene Is found on the female chromosome, of which males only possess one copy. Males with TMLHE mutations cannot produce their own carnitine, and it is shockingly common. Approximately one in every 350-400 males of western European descent carries a mutation that inactivates the gene. While a diet with red meat is a significant source for carnitine, carnitine levels can vary five-fold from person to person, including in women.
The work of Xie and Bankaitis shows that carnitine deficiencies interfere with neural stem cells’ abilities to promote and organize embryonic and fetal brain development. They suggest that such deficiencies during pregnancy may likely increase autism risk for in TMLHE-deficient male fetuses. This conclusion has interesting implications. First, pregnant women practicing “healthy” lifestyles, such as vegetarian or vegan, may be exposing male fetuses to increased autism risk given that vegetables and fruits are not rich sources of dietary carnitine. Second, the conclusion suggests that carnitine supplementation could be an effective preventative measure for those cases of autism risk.
“Similar to folic acid’s role in pregnancy to protect against brain and spinal cord defects, specifically spina bifida, introducing carnitine into the diet of a woman who is pregnant or trying to become pregnant, could potentially reduce the risk of her child developing autism,” Xie said.
“Autism is typically diagnosed between the ages of 2 and 3 when you can observe behaviors, but that does not mean the event that lead to the autism occurred during that time, Bankaitis said. “Researchers are trying to pinpoint the developmental stage in which the triggering event likely occurred. In fact, our work suggests that the seeds of autism risk are already sown early in pregnancy for women with low carnitine levels carrying male babies with TMLHE mutations. ”
ASDs can be broken down into two different major categories of signs. Some disorders are associated with physical abnormalities—the stature, composure, movement or mental capabilities of a person. These are relatively easy to detect.
The second area of ASDs consists of purely behavioral abnormalities that are observed through watching a person interact, which can be much more ambiguous. “Normal behavior is a wide spectrum of behaviors, and autistic children sit at the extremes of that spectrum,” Xie said. “This is how behavioral issues are diagnosed.” Of course, some people with an ASD might have both physical and behavioral signs.
Poor coordination or making repetitive motions like rocking or spinning, exhibiting characteristics of social detachment like avoiding eye contact or physical touch or underdevelopment of speech that results in no to very limited speech and tendencies to repeat phrases, which is known as echolalia, can all be other symptoms of autism. Digestive complications, sleep problems and seizures, which occur in about one-third of people with autism, could also be symptomatic of an ASD.
While they are all currently classified as ASDs, the following were previously referred differently based on their type, ranging from mild to severe:
- People with Asperger’s syndrome are very intelligent and intensely focused on their interests but have difficulty responding to social cues;
- Those with pervasive developmental disorder, not otherwise specified (PDD-NOS) exhibit behavioral and communications issues and perform repetitive movements;
- Autistic disorder is characterized by similar symptoms of PDD-NOS but are intensified; and
- Childhood disintegrative disorder, the rarest ASD condition, results in loss or reversal of social, language or motor skills.
Early treatment, ideally before the child turns 3 years old, is key to addressing the complications that stem from an ASD diagnosis, which is why guidelines call for children to be screened at nine, 18 and 24 months, with more screenings to follow if the child continues or begins to demonstrate worrisome behaviors.
“The landscape of how ASDs are diagnosed is always changing, and the elevated incidence of ASD is no doubt partly due to the fact that diagnosis has been redefined,” Bankatis said. “However, the elevation in ASDs is not related solely to a redefinition of how you diagnose it. It is actually on the rise.”
No test has yet been developed to diagnose autism. Throughout a baby’s and toddler’s series of regular checkups, a health care provider will observe the child’s responses to the parent or guardian and their expressiveness. Numerous tests to evaluate hearing quality, speech development, social behaviors, potential lead poisoning or other developmental problems can be administered to determine if a child’s behaviors are caused by something other than autism.
There is no medical treatment for autism. Therapies can assist in managing autism symptoms and enhance a person’s ability to socialize and engage with others.
Children with autism tend to develop their speech later than children without autism, so speech therapy may be used to help improve the child’s speaking capabilities. Some with severe verbal issues may use assistive technology to convert pictures or text into audible forms of communication. Behavior intensive programs work improve social skills by promoting positive responses and discouraging negative reactions. There are also a number of educational resources and therapies required by law that are available at local schools for children with these needs. Working with a school to establish an individualized education program for a child with autism could help that child learn and develop. Some anti-psychotic or anti-convulsant medications may help treat aggression and seizures, respectively.
“Research has come a long way toward determining the cause and treatments for autism,” Xie said, “but we still have much to learn, given the complexities of the disorders and the inherent complexities of the brain.”
Autism Speaks and the Autism Society of America list a number of resources for those looking to learn more about autism, but you should speak with a health care provider if you believe your child or another loved one might have an ASD.
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