When It Comes to Autism, Environment Matters

environmentThere is more than genetics at play if your anxious child is suffering from autism spectrum disorder (ASD).  About 10 percent of the population suffers from some form of ASD, which can include symptoms that range from repetitive behavior to problems interacting or communicating. While heredity factors have long been known to play a part in ASD, a study published in Molecular Psychiatry found that certain environmental factors may also play a role.

These factors could contribute to the development of ASD by affecting the expression of genes without changing the genes’ underlying DNA, resulting in alterations known as “epigenetic changes.” In other words, the ASD gene may still be part of a child’s makeup, but the child may not suffer from any symptoms if the ASD gene remains “silenced.”

The Great ‘Silencer’

In the case of this study, the research team looked at a component called DNA methylation, which can act as a “silencer” that blocks a gene’s expression. After reviewing DNA samples of 50 pairs of identical twins, the study found:

  • 34 pairs consisted of one twin with ASD and one twin without ADS
  • 5 pairs had ASD in both twins
  • 11 pairs had no ASD in either twin

For the 45 pairs of twins that had no ASD or only one twin with ADS, it appeared the great silencer was at work blocking the expression of the condition. All twins who suffered from ASD had certain genetic sites with altered DNA methylation, while the alteration of DNA methylation at other genetic sites varied.

The Possible Environmental Culprits

But don’t go investing in a dozen air purifiers just yet. While the study pointed to the impact of environmental factors in the development of ASD, it didn’t yet point out what those exact environmental factors might be. Epigenetic changes can happen during a child’s lifetime or before a child is even born, and any number of environmental culprits may be to blame.

Previous studies showed that the risk of pregnant women having children with ASD was influenced by:

  • Stress
  • Diet
  • Exposure to viral or bacterial infections
  • The drug thalidomide, which is used to treat certain skin conditions

Environmental factors that may cause epigenetic changes after children are born include:

  • Nutrition
  • Certain compounds, such as nicotine and alcohol
  • Certain chemicals found in the home or workspace
  • Certain medications

The Good News

The study brings good news on several fronts. As something this groundbreaking will likely lead to more studies, we may someday be privy to the exact environmental factors that play a role in the development of ASD.

And even better news?

Epigenetic changes may be reversible.

“Research into the intersection between genetic and environmental influences is crucial because risky environmental conditions can sometimes be avoided or changed,” study co-author Jonathan Mill said in a PsychCentral article.

That may mean certain anxious children suffering from ASD may need not suffer any longer, or those at risk for developing it could learn to avoid conditions that heighten the risk.


Photo Credit: Olof S via Compfight cc