Autism risk associated with parental age and with increasing difference in age between the parents
Previous studies have repeatedly suggested that there may be an association between parental age and the autism risk of their child. A large-scale international study has now analysed this association in more detail and confirmed that having very young or old parents, as well as parents with a large age gap, increases the likelihood of a child having autism.
In co-operation with a team of international colleagues, researchers from the Karolinksa Institute in Stockholm (Sweden) analysed autism rates in 5.8 million children, including more than 30,000 with autism. The children were born between 1985 and 2004 in Sweden, Denmark, Israel, Norway and Western Australia.
The analysis showed that not only the age of both parents, but also the age gaps between them, increase the risk of autism. The risk was highest among fathers over 50 years of age (66 per cent higher than fathers in their 20s). Women who gave birth to children in their 40s increased the children’s risk of autism by 15 per cent compared to those born to mothers in their 20s. In teen mothers the autism risk was 18 per cent higher.
The age gap between parents also had an impact. The highest risk was found in men aged between 35 and 44 with partners who were 10 or more years younger, as well as in women in their 30s who had partners who were 10 or more years younger.
“Although parental age is a risk for autism, it is important to remember that, overall, the majority of children born to older or younger parents will develop normally”, emphasised co-author Sven Sandin from the Karolinska Institute.
Molecular Psychiatry advance online publication 9 June 2015; doi: 10.1038/mp.2015.70
Correspondence: Dr S Sandin, Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Nobels vag 12A PO Box 281, Stockholm SE-17177, Sweden. E-mail: sven.sandin@ki.se