Fwd: - Research points to new causes of autism

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Posted on Fri, May. 21, 2010

Research points to new causes of autism

By Marie McCullough

Inquirer Staff Writer

Could delayed childbearing, infertility treatment, and premature birth

contribute to autism?

Research presented this week in Philadelphia suggests the answer is yes.

The International Meeting for Autism Research, attended by more than 1,700

scientists and advocates at the Philadelphia Marriott Downtown, offered

provocative findings from studies of large population groups. Such

epidemiological research can uncover risk factors that are too subtle to

detect in small groups or individuals.

At this point, experts can only guess at the biological basis for the links

they're finding. And those clues are not enough to recommend changes in, for

example, infertility treatment.

Still, knowing who may be at risk of autism could improve diagnosis, which

might enable earlier intervention.

One study, led by the University of Pennsylvania and Children's Hospital of

Philadelphia, followed babies who weighed less than 4.4 pounds at birth

through to age 21. Nearly 5 percent of these 623 young adults had an

autism-spectrum disorder, five times the rate in the general population.

" Clearly, screening for autism-spectrum disorders in low-birth-weight

survivors is critical, " said lead author Pinto-, a Penn

School of Nursing epidemiologist.

Autism includes a host of developmental disorders of varying severity marked

by communication problems, compulsive behaviors, and inappropriate social

interactions.

Last year, government researchers estimated that in 2006, the disorders

affected 1 percent of U.S. children. Though that is in line with rates in

other countries, it is 57 percent higher than the U.S. rate in 2002.

Better diagnosis can't fully explain the dramatic increase, experts agree.

In searching for explanations, researchers are looking at lifestyle changes.

In recent decades, women have been delaying motherhood, which increases both

their chance of needing fertility treatment, and their chance of having a

low-birth-weight baby, typically due to prematurity.

These changes have emerged as risk factors for autism:

Two studies presented Thursday linked infertility treatment to the chance of

autism. A Harvard University study of 3,985 nurses found that using

ovulation-inducing drugs to overcome infertility nearly doubled the odds of

having an autistic child. A Tel Aviv University study of 564 autistic

children found they were three to four times more likely to have been

conceived through in-vitro fertilization and to have been born at very low

weights than children in the general population. The mothers of autistic

children were also older - 33 on average - compared with 31 for the others.

A Danish study of more than 8,000 children diagnosed with autism found that

very low birth weight (less than 3.3 pounds) increased autism risk. However,

weight was a stronger risk factor for girls than boys, even though autism is

four times more common in boys. Being slightly underweight increased the

risk by 50 percent for girls, but not for boys.

A Columbia University study that has followed 108,000 Norwegian infants

through age 7 found autism was more common among those whose heads were

abnormally small or abnormally large in the first year of life. The

researchers said " pediatricians should carefully record " babies' head

measurements as a possible indicator.

There were also some reassuring results. A study led by the University of

North Carolina concluded that although smoking during pregnancy isn't

advisable, it doesn't increase autism risk, as was previously thought.

And the Kennedy Krieger Institute in Baltimore debunked the idea that the

stress of having an autistic child drives most parents to divorce. Using

data from a 2007 national survey, Krieger researchers found that 64 percent

of autistic children live with two married parents - compared with 65

percent for other children.