The Environment and ASD Risk: Putting It Together

Interviewer: Laurie Scudder, DNP, NP; Interviewees: Eliza M. Gordon-Lipkin, MD; Paul H. Lipkin, MD

Disclosures

July 27, 2017

Environmental Factors

Medscape: Much concern has been raised about environmental pollutants. Is there evidence that air pollution or other chemical exposures may be a factor?

Dr Gordon-Lipkin: There are several studies that have linked environmental pollutants to autism risk. Two conducted in California[2,3] and one in Taiwan[4] suggest that there might be exposures in the environment, including water and air pollutants, that increase the risk for autism. However, a more recent study conducted in twins in Sweden did not find an association.[5]

I think this is something that will be further investigated in the coming years, as it is a question of much public interest. We don't now have definitive evidence that any one specific chemical is at fault here.

Medscape: Many researchers suspect that more important than a specific environmental factor is the gene–environment interplay that you have already mentioned.

Dr Gordon-Lipkin: I do think that the gene–environment interplay is a key concept in autism risk. It may come down to certain genetic risk factors that put a child at risk for vulnerabilities to environmental exposures.

Dr Lipkin: I agree that the big shift in thinking that has occurred over the past 10 years is the result of the tremendous amount of both laboratory and population-based evidence supporting this interplay. That remains a prime area of concern, with the evidence continuing to suggest that multiple factors in the environment affect brain growth through gene control and mediation. It is this interaction of genes and environmental exposures, defined very broadly—prenatal, perinatal, or postnatal—that is probably an important contributor to ASDs and most likely many other neurodevelopmental conditions.

It is this interaction of genes and environmental exposures, defined very broadly—prenatal, perinatal, or postnatal—that is probably an important contributor to ASDs.

Dr Gordon-Lipkin: And I think this ties into the concept of precision medicine, in which every individual will have a certain constellation of genes that dictate risk to specific factors in their environment. The interplay between their specific environment and their genes will determine the outcome.

What Do You Tell Patients?

Medscape: What is your advice to a woman who is contemplating pregnancy and is concerned about ASD? Other than common-sense recommendations to avoid alcohol and smoking; eat a well-balanced diet; and appropriate, cautious use of medications, is there anything else you would add?

Dr Gordon-Lipkin: I think the really important concept to understand when talking about risk factors for autism is to begin by recognizing that some of these are controllable and some of them are not. We must differentiate between them and be sure that an expectant mother knows the difference.

Again, those factors that are controllable are things like folic acid consumption and avoidance of alcohol and smoking. But noncontrollable factors include certain genetic risk factors. For women who have a child with autism and are contemplating a second pregnancy, a conversation about genetic testing would be important.

Dr Lipkin: When it comes to genes and the environment, it is no longer whether it's either/or. What we now have are biomechanistic explanations of the influence of one upon the other.

We've always known that identical twins are never 100% alike but we've never quite understood why. And now we have a better understanding. But more important, in terms of health—and in this case, neurodevelopmental disabilities—we now have a better understanding about the interplay between the genes and the environment, which probably is an important contributor to the causes of autism.

Follow Dr Paul Lipkin on Twitter: @PaulLipkinMD
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