September 11, 2007- Children exposed to high levels of testosterone in the womb showed more autism-related traits later in life, according to findings that suggest the male hormone may play a key role in the complex brain disorder.
The results support a hypothesis that higher levels of testosterone may contribute to autism and reinforce findings from tests on animals, said Simon Baron-Cohen, director of the Autism Research Centre at Britain's Cambridge University, who worked on the study.
He called the findings of the ongoing research promising but cautioned that they did not show a direct link between autism and testosterone and said other factors could be involved. None of the 235 children in the study had autism.
"It is a significant correlation and remains significant after you control for other factors," he said on Tuesday at a meeting sponsored by the British Association for the Advancement of Science.
What is causing the spike in testosterone was not clear, though Baron-Cohen said environmental factors could be at play.
Autism symptoms range from mild awkwardness seen in Asperger's syndrome, to severe disability and mental retardation. A recent survey found that 1 in every 150 U.S. children has autism or an autism spectrum disorder, a less severe condition related to autism, such as Asperger's.
The rate is slightly lower in Britain.
No one knows what causes autism, a complex developmental disorder that includes problems with social interaction and communication.
But earlier this year, scientists published a large study indicating that autism has numerous genetic causes.
Experts agree that autism, a spectrum of disorders, is likely caused by environmental factors working on a child with a genetic predisposition. Testosterone in the womb might be one such factor.
In Baron-Cohen's ongoing study, the researchers measured fetal testosterone levels from pregnant women who had amniotic fluid taken for other reasons.
When the children were eight years old, the researchers used questionnaires to see whether they preferred social to solitary activities and how empathetic they were.
This allowed them to measure traits, which in an extreme form, are indicative of autism. In the study children with higher levels of fetal testosterone were better at things such as remembering patterns but not as interested in socializing.
The next step is collaborating with Danish researchers to tap a biological bank that has about 90,000 amniotic fluid samples to test whether there is a direct link between fetal testosterone and autism.
"This may provide us with a marker to help tell us who might be at risk," Baron-Cohen said.
Mon, June 2, 2008 (HealthDay News) — Children who are born underweight or early have more than double the risk of developing autism, new research shows.
The risk was especially pronounced among low-birth-weight girls, said the authors of the study, which was published in the June issue of Pediatrics.
The study, by researchers at the U.S. Centers for Disease Control and Prevention, helps tease out the mysterious underpinnings of this disorder but is unlikely to translate into benefits for patients anytime soon.
"This gives us more clues [about autism], which we desperately need, but it's not anything clinicians can use right away," said Dr. Cindy Molloy, an autism researcher and clinical assistant professor of pediatrics at the Center for Epidemiology and Biostatistics at Cincinnati Children's Hospital.
The results do reinforce the importance of monitoring children who are born underweight or early for behavioral problems so they can be treated, said study author Diana Schendel, lead health scientist at the CDC's National Center on Birth Defects and Developmental Disabilities.
So-called "autism-spectrum disorders" are a group of developmental disorders characterized by social and communication problems. According to the National Institute for Neurological Disorders and Stroke, some three to six children out of every 1,000 will have autism, while males are four times more likely to develop the disorder than girls.
Previous studies have indicated that low birth weight and being born premature are important risk factors for developmental problems generally in children. But the association between these factors and autism is less clear.
A Canadian study published earlier this year did find that premature infants who were born at a very low birth weight — about 3.3 pounds — were more likely to screen positive on tests of autistic behaviors, but the findings were considered preliminary.
The investigators on the current study looked at 565 children with autism born in metropolitan Atlanta between 1986 and 1993, and compared them to a set of children without autism, as well as to children with other developmental disabilities, such as mental retardation, cerebral palsy, hearing loss or vision problems.
Overall, low birth weight was associated with a twofold increased risk for autism, but the risk was higher for girls than for boys.
For all low-birth-weight children, the risk for autism accompanied by other developmental problems, such as mental retardation, was higher than the risk of developing autism alone.
There was also double the risk for developing autism in babies born prematurely, although this was primarily due to a more than fivefold increased risk in girls born early.
"This was one of the first studies that had a large enough sample to look at girls," Molloy said. "They really were able to tease out what is different about boys and girls."
Even so, the elevated risk for autism seen in low-birth-weight and preterm babies was much lower than that linked with cerebral palsy, mental retardation, hearing loss or vision impairment.
"It's not yet clear why being small or being born too soon could lead to these problems but, Schendel said, "[these factors] could be a marker for an impaired fetus, one that has a neurological problem which is retarding its growth. On the other hand, being small or being born too soon may be related to factors that could harm the neurological development of the fetus such as infection during pregnancy."
The findings support the idea that there are different kinds of autism and different mechanisms underlying those cases, Molloy said.
Thu, Apr 24, 2008 (HealthDay) — The first study to show a statistical relationship between autism and proximity to industrial sites that release mercury has been published by researchers at the University of Texas Health Science Center at San Antonio.
Their analysis of data from 1,040 Texas school districts and data from 39 coal-fired power plants and 56 industrial facilities in the state showed that autism rates decreased by one percent to two percent for each 10 miles of distance from a mercury pollution source.
Among the other findings:
• For every 1,000 pounds of mercury released by all industrial sources in Texas in 1998, there was a corresponding 2.6 percent increase in autism rates in Texas school districts in 2002.
• For every 1,000 pounds of mercury released by Texas power plants in 1998, there was a corresponding 3.7 percent increase in autism rates in Texas school districts in 2002.
The research appears in the journal Health & Place.
"This study was not designed to understand which individuals in the population are at risk due to mercury exposure. However, it does suggest generally that there is greater autism risk closer to the polluting source," lead author Raymond Palmer, associate professor of family and community medicine, said in a prepared statement.
