Children who are born to teenage mothers and those whose parents have a relatively large age gap between them are at higher risk of having autism, according to a new study.
Autism spectrum disorder (ASD) is a condition that affects social interaction, communication, interests and behaviour. NHS figures show that one in every 100 people are diagnosed with autism.Past research has shown a link between advancing parental age and autism risk, although the association is unclear.
For example, some studies noted an increased risk with older fathers, but not mothers.New research, funded by non-profit organisation Autism Speaks, set out to investigate the relationship between advancing maternal or paternal ages and autism risk, and the extent of this.For the study, researchers analysed autism rates among 5,766,794 children, of which more than 30,000 had the condition.
The children were born between 1985 and 2004 in either Israel, Denmark, Norway, Sweden and Western Australia.Their development was followed up until 2009, which involved checking national health records for any diagnoses of autism.It was revealed that children born to teenage mothers were 18 per cent more likely to develop autism than those born to women in their 20s. In contrast, autism rates were 15 per cent higher in children born to mothers in their 40s, in comparison to those born to women in their 20s.Furthermore, children born to men aged over 50 had a 66 per cent increased risk of autism than those born to fathers in their 20s. It was also noted that autism rates were higher the wider the gap between parental ages.
The authors concluded: 'These results suggest that multiple mechanisms are contributing to the association between parental age and ASD risk.'
Abraham Reichenberg, co-author of the study, added: 'When we first reported that the older age of fathers increases risk for autism, we suggested that mutations might be the cause. Genetic research later showed that this hypothesis was correct.'In this study, we show for the first time that autism risk is associated with disparately aged parents. Future research should look into this to understand the mechanisms.'
The study has been published in the journal Molecular Psychiatry.