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Autism and Prenatal Development

Autism Speaks neuroscientist Dan Smith answers questions about this week’s breakthrough report in the New England Journal of Medicine
March 28, 2014

Our recent news report “Direct Evidence that Autism Starts During Prenatal Development” continues to spark tremendous interest and discussion on both the story’s webpage and the Autism Speaks Facebook page. Autism Speaks helped fund the study, which also took advantage of postmortem donations of brain tissue to the Autism Speaks Autism Tissue Program. We’ve asked Dan Smith, Autism Speaks senior director of discovery neuroscience, to answer the questions coming up most frequently in the ongoing conversation. (Note: Dr. Smith was not directly involved in the research.)


How could the researchers know they were looking at prenatal brain development if the donated brains came from children old enough to be diagnosed with autism when they died?

Dr. Smith: The research detected that the brains from children with autism had changes in how specific groups of brain cells were organized. A rich body of neuroscience research tells us that the different parts of the brain develop at different times during prenatal development. This is why the researchers could draw conclusions on when the disorganized patches of brain cells developed.

If autism has to do with prenatal development, how come our child seemed fine until age two?

Dr. Smith: Autism is a spectrum in every way. This includes how and when it becomes detectable in any individual. There may be rare cases where no signs or symptoms are seen before a steep drop in functioning occurs. In most cases, though, signs begin emerging in early childhood. That said, it can be very difficult to detect autism in very young children because their range of behaviors is so limited - and we currently diagnose autism strictly through observing behavior.

The latest thinking in the field of autism research is that subtle signs and symptoms are there in most very young children who will go on to be diagnosed with autism. But they can be extremely difficult to notice – even for experienced physicians! New technologies are going to be vital in proving whether this thinking is correct. For example, recent research has revealed subtle deficits in eye contact and social attention in babies that went on to be diagnosed with autism. These differences could be detected only with sophisticated eye-tracking technologies.

Clearly, we need more funding for research to address these questions.

Was it something I did or was exposed to during pregnancy that would have caused these brain patches to develop in our son? Thank you to the families who made these donations to science - for our future children.

Dr. Smith: While it’s common for parents to wonder what they did wrong, it’s very important to emphasize that autism isn’t something that any parent “did” to his or her child. We don’t know what caused the disorganized brain-cell patches that the researchers found in this study. It’s essential that the discovery of these patches leads to more research on this exact issue.

Can brain scans show these autism patches when a child is alive?

Dr. Smith: That’s a great question, and you can bet that researchers are going to push the limits of current brain imaging technologies to find out!

Why or when do these changes occur during prenatal development?

Dr. Smith: It’s likely that these changes occurred during the second trimester of pregnancy, when brain cells specialize and move into their correct positions in the cerebral cortex. But we don’t yet know why these disorganized brain patches developed. It’s an important question, and we are funding follow-up research on these important findings through a Meixner Postdoctoral Fellowship in Translational Research for Haim Bellinson, at the University of California, San Francisco.

Why did this study look at just 22 donated postmortem brains? Why not more, and why do we need actual donated brains?

Dr. Smith: Fortunately, relatively few families have to experience the tragic loss of a child – and this is no different for families affected by autism. As a result, the scientific community has a very limited amount of postmortem organ donations from children – with or without autism. We are deeply grateful to all of the families that make this extremely generous donation when tragedy occurs – or even better, register their family with an autism brain bank with a thought for the future. The breakthroughs that can come from studying these tissues are unmatched. They will greatly advance our knowledge of the causes of autism and the development of effective treatments.

Where can I find out more about registering our family to donate our brains (not quite yet) to science?

Dr. Smith:  We strongly encourage individuals and entire families to register as future donors of brain tissue for research through the Autism Speaks Autism Tissue Program. The program is currently in the process of becoming a founding member of a new and larger repository called Autism BrainNet. Learn more here. Or go right to the registration form here.