California Autism Twins Study: Nature-Nurture Conundrum

What causes autism? Just last month we shared some important new science about genetic clues. (See our June 12 post, "Autism: Genetic Mutations New Cause For Excitement.") Now a study published last week in the Archives of General Psychiatry, looking exclusively at autism in fraternal twins, makes a strong case for environmental causes—specifically in the pregnancy and birth environment. Genetics alone could not account for high rates of autism spectrum disorder (ASD) among nonidentical twins.

Autism Speaks summarizes:

The California Autism Twins Study suggests environmental influences, which could include parental age, low birth weight, multiple births, and maternal infections during pregnancy may greatly increase risk for ASD. The study suggested that both genetic and shared environmental factors significantly increase risk for ASD: an estimated 38 percent of risk being associated with genetic heritability and 58 percent with the environment that twins share during pregnancy and perhaps early infancy. The study also found that the relative contributions of shared genes and shared environment are similar for males and females.

These interesting findings once again provide more questions than answers. They also stoke the heated war of words between outspoken factions in the autism community. We direct your attention to CommonHealth for a brief, clear, and fair backgrounder by guest blogger Karen Weintraub, who helpfully organizes the current research into environmental causes: (1) immune problems; (2) chemicals in the air, water, food, or on the ground; (3) problems during birth or delivery; (4) medications; and (5) nutrition.

You will next hear from us on this topic when we publish our updated and upgraded autism page. Then you will not hear from us again until someone publishes meaningful new clinical evidence to support any practical role for hyperbaric oxygen in addressing this national public health crisis.

O2.0 is the news blog of HyperbaricLink, the independent web guide to hyperbaric oxygen therapy.