While much research has been done to identify potential genetic causes of autism, the new study led by Sven Sandin, of the Karolinska Institutet, Sweden and King’s College London, suggests that non-heritable and environmental factors may also play a role in children’s risk for autism.
The researchers compared the risk of autism in different groups of material age (under 20, 24-29, 30-34, and 35+).
They found that children of mothers older than 35 years had 30 percent increased risk for autism. Children of mothers under 20 had the lowest risk of developing autism.
The association between advancing maternal age and risk for autism was stronger for male offspring and children diagnosed in more recent years.
The analysis included 25,687 cases of autism spectrum disorder and over 8.6 million control subjects, drawn from the 16 epidemiological papers that fit inclusion criteria for the study as defined by the investigators.