A new study suggests that autism is not a plain result of hereditary factors; 50 percent of it is triggered by environmental factors such as birth complications, socio-economic status, or parental health and lifestyle.
Researchers from the King's College London and Sweden's Karolinska institute led by research student Sven Sandin studied the cases of 25,687 participants diagnosed with autism spectrum disorder. They specifically looked at the possible link of environmental factors such as the maternal age and exposure to environmental toxins on the increased risk of autism.
Their analysis revealed that those with mothers aged 35 and above is 30 percent more likely to have autism.
"The study makes us confident there is an increased risk for autism associated with older maternal age, even though we do not know what the mechanism is. It has been observed in high quality studies from different countries, including the US. All studies controlled for paternal age which is an independent risk factor for autism. This finding adds to the understanding that older age of the parents could have consequences to the health of their children," Sandin said in a press release.
The researchers also looked at the genetic risk of autism development. They found out that the risk is 10 times higher for males and those with siblings who have autism; thrice for half-brothers and half-sisters; and twice the risk for cousins.
"At an individual level, the risk of autism increases according to how close you are genetically to other relatives with autism," said Sandin in an interview with Reuters. "We can now provide accurate information about autism risk which can comfort and guide parents and clinicians in their decisions."
This is not the first time that a study attempted to link environmental factors to autism. In an earlier study conducted by researchers from the University of Chicago, they concluded that exposure to environmental toxins increases the risk of developing autism. However, they are yet to pinpoint the exact toxins that trigger this development disability which could be possibly due to the chemicals found in plastics, food cans, and other common products.
Sandin's study was published on the journal JAMA Child and Adolescent Psychiatry.
