June 18, 2013
Two New Studies Explore Causes And Symptoms of Autism
Brett Smith for redOrbit.com - Your Universe Online
Two recent studies showed some novel findings on the causes of autism and one of its symptoms. One study from researchers at Harvard University showed a connection between air pollution and the developmental disorder, while another study from Stanford University demonstrated that autism-associated language disorders are the result of faulty brain wiring.
In the first study, Harvard researchers found American women who are exposed to high levels of air pollution are up to twice as likely to have a child with autism as women who lived in areas with low pollution, according to their report in the journal Environmental Health Perspectives.
"Our findings raise concerns since, depending on the pollutant, 20 percent to 60 percent of the women in our study lived in areas where risk of autism was elevated," said lead author Andrea Roberts, a research associate with the Harvard School of Public Health.
The Harvard team looked at data from Nurses' Health Study II, a long-term study involving almost 120,000 nurses that began in 1989. Within this study group, the authors focused on 325 women who had autistic children and 22,000 women who had non-autistic children.
Using air pollution data from the Environmental Protection Agency, the researcher calculated these women's exposure to pollutants while pregnant. They also adjusted for the influence of income, education and smoking during pregnancy when making their autism risk assessments.
The Harvard team´s results showed women who lived within the highest 20 percent of locations for diesel particulates or atmospheric mercury were twice as likely to have a child with autism as those who lived in the lowest 20 percent.
Study author“¯Marc Weisskopf admitted that the EPA data was taken every four years, making it somewhat imperfect. The researchers also weren´t able to track the women´s travels outside their homes.
“There´s a lot of error in estimating what the mother´s exposed to,” Weisshopf told Bloomberg News. He added the study´s sample size is large enough to warrant further investigation.
In the Stanford study, researchers looked at how the speech regions of autistic volunteers´ brains were connected to other areas. The study included 20 children with autism who were determined to be high functioning, with language skills and communication. MRI imaging scans of their brains were compared with 19 other children who did not have the disorder.
The researchers found relatively weaker links in autistic participants´ brains between the area where speech is controlled and the brain´s dopamine reward pathway, according to the team´s report in the“¯Proceedings of the National Academy of Sciences.
The researchers also discovered weak connections between the autistic brain´s voice regions and those that process emotional information. According study co-author Daniel Abrams, the Stanford researchers plan to investigate elements of speech that could activate an autistic child´s brain.
“There isn´t a lot of data to strongly point at what are the root causes of the social deficits in children with autism,”“¯Abrams, a postdoctoral research fellow at“¯Stanford, told Bloomberg. “We think it has this important motivation and reward component to it.”