Tuesday, February 8, 2011

Trying to Understand the Causes of Autism

Craig Newschaffer, Ph.D.
Professor, Drexel University School of Public Health
Primary Investigator, EARLI Study
Reprinted with permission from Special Families Guide

It was a notable year for autism on screen. Two decades removed from Rain Man, a major studio released a film featuring a protagonist with autism. The movie Adam took the well‐trod cinematic road of probing a relationship between twenty‐somethings in New York City, only this time one of them had Asperger’s syndrome. In February HBO premiered a biopic on Temple Grandin, a university professor with autism whose life and world‐view have already inspired the millions who have read her books. The fictional Lisbeth Salander, eponymous heroine of The Girl with the Dragon Tattoo which is now gracing art houses around the country, has Asperger’s Syndrome and a counterculture edge both of which she deploys freely in solving a forgotten string of gruesome murders.
Given all the recent celluloid attention devoted to autism, one may wonder whether we are already well‐enough aware. Unfortunately, in the area where I spend my days – the science of trying to understanding autism’s causes ‐ we still remain very much in the dark. Indeed, autism remains a growing public health epidemic.
One thing we do know is that autism is strongly influenced by genetics and we even have some clues about particular genes likely to be involved. But the genetics of autism are far more complex than first imagined. No single common gene by itself causes autism – individuals with autism probably carry many different combinations of multiple genetic mutations. Some of these mutations are inherited, but others are new ‐ appearing for the first time in affected individuals while completely absent from their parents’ genomes. A portion of autism’s genetic risk may not even be carried in the standard DNA alphabet – a newly discovered system of DNA on/off may also be commonly involved. And then, at least in some cases, genetics may only come into play by making the brain of a developing fetus, baby, or child more susceptible to the influence of some exposure in the environment.
Important investigations of the influence that environmental exposures, like infections and chemicals, may have on autism risk have really only recently begun in earnest. The Early Autism Risk Longitudinal Investigation (the EARLI study), which my colleagues and I launched last summer, is designed explicitly to explore environmental influences on autism risk while acknowledging the importance of genetic susceptibility. The study is nationally coordinated by the Drexel University School of Public Health, and includes participating institutions in Baltimore and northern California. In EARLI we will follow over one thousand mothers of young children with autism from the start of a subsequent pregnancy to the time the baby is born. We continue following the new baby through its third birthday – all the while collecting comprehensive information on a wide range of exposures and assembling genetic data from the family.
So, while the movie of autism’s causes remains very much the mystery story, there are encouraging plot points. Investment in autism research has increased markedly – in fiscal year 2008 the federal government committed nearly $120 million dollars to autism research, and then added another $85 million through the economic stimulus. As a result, a number of large, comprehensive studies investigating the complex causes of autism, like the EARLI Study, are now underway. What we ultimately learn about causes will be invaluable in guiding next generation strategies for minimizing impairment and maximizing potential for individuals with autism.

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