Autism and a Link to Brain Development

A new genetic discovery and chelation therapy are in the news this week.


It's been an amazing year for discoveries about autism and genes-and it's only July. The latest news: Some genes involved in the disorder may affect the brain's ability to develop in response to experience, a key aspect of learning.

That follows the report in January that scientists with the Boston-based Autism Consortium had found a genetic variation on chromosome 16 shared by 1 percent of people with autism. In March, researchers reported that about 15 percent of autism cases result from random spontaneous mutations that are unique to each person, rather than an inherited "disease gene."

Now it appears that those random mutations may mess up the wiring at a critical time when experience helps shape the developing brain. This latest bit comes from researchers at Harvard University, who analyzed the genes of 88 Middle Eastern families in which cousins had married. Intermarriage increases the odds that rare mutations will occur and be passed on, making patterns easier to find. The researchers' results, published in Science, are not a slam dunk, but they do provide more evidence that gene-hunting scientists are on the right track.

Daniel Geschwind, a professor of neurology at the University of California-Los Angeles who studies the genetic basis of autism, says he's most intrigued by the indication that genes that at first glance appear to have nothing in common might actually be linked by the fact that they are vital to brain development and are turned on and off by the brain's response to experience. It makes sense, since symptoms of autism emerge in early childhood, when the brain is feverishly forming new connections. If the genes are turned off, maybe those connections don't form. It's also when children are learning speech and social interaction, two key abilities often impaired by autism. This may explain why using behavioral therapies as early as possible, in which children practice social interaction and communication, are the best treatment so far for autism.

On the treatment front, chelation therapy is also in the news, with the announcement that the National Institutes of Mental Health is moving closer to studying the effectiveness of this controversial treatment for autism.

Chelation is designed to treat poisoning by heavy metals, such as lead. Since one theory is that autism can be caused by exposure to mercury, a toxic metal that was used until 2003 as a preservative in early childhood vaccines, it makes sense to think chelation might help. But there is no validated research on its value as an autism treatment. Most doctors say it is ineffective and could be dangerous. On the other hand, some parents of children with autism think chelation has been hugely helpful in reducing symptoms. About 2 percent of children with autism participating in the Interactive Autism Network at the Kennedy Krieger Institute in Baltimore have had chelation therapy, according to the Associated Press. Since there is no evidence-based medical treatment for autism right now, parents are really on their own in trying to figure out what works best. It's not a pleasant place to be.

Earlier this week, the Associated Press reported that Tom Insel, the director of the National Institute of Mental Health, supports testing the effectiveness of chelation therapy on children to see if it can be proved safe and effective. The autism blogosphere lit up, and advocates of chelation therapy were elated. But as with all things concerning autism, alas, the story's not at all simple.

The chelation study was first approved by NIMH in 2006. In February 2007, a study showed that giving chelation to rats who weren't suffering from heavy-metal poisoning caused permanent cognitive impairment. Whoa. That sent NIMH back to more risk-benefit analysis. It filed an application with the Food and Drug Administration to study chelation as an investigational new drug (an IND, in FDA-speak).

The knowledge gleaned from the study will be limited, since only 120 children are to be enrolled: half will get chelating agent for 12 weeks and the other half, a placebo. The children's blood mercury levels and autism symptoms will be monitored along the way. That's too few subjects to get a clear sense of whether chelation works. But it's better than what we've got now.

This kind of testing, which will follow standards used for clinical trials on FDA-approved drugs and treatments, is what's desperately needed for alternative medical treatments, particularly those given to children. After secretin became popular as an autism treatment in the 1990s, it took years for scientists to get around to doing trials. When they did, no benefit was found, and secretin has been largely abandoned.

When doctors choose new treatments to study, they pick the ones they think are most likely to succeed. Since most mainstream docs think chelation and other alternative treatments are quackery, those treatments don't get picked. Yet if the docs would buck convention and apply solid scientific analysis to these treatments, parents would start getting the good information they desperately need in making choices about treatments.

Clinical trials are risky, especially with children. But thousands of parents are already experimenting on their kids. They deserve some help from the pros.