Researchers have presented a new study which suggests that parents with an age gap of 10 years or more may have a higher risk of having a child with autism. The study was based on the analysis of almost 6 million children from Australia, Israel, Denmark, Sweden and Norway and, while previous research has already established an association between older fathers and autism, it’s the first to explore whether the difference between paternal and maternal ages is a possible risk factor.
Co-author of the study Michael Rosanoff from Autism Speaks explained how linking the national health registries of five countries created the world’s largest dataset for autism risk factors, allowing the team to look at the relationship between the age of the parents and autism, with the study aiming to establish whether maternal and paternal ages increased the risk of autism and, if so, to what extent.
Of the 5,766, 794 medical records examined, over 30,000 of the children had been diagnosed with ASD. The researchers discovered that ASD was 66% higher if the child had a father over 50, and 28% higher in children with fathers over the age of 40, compared to those children with fathers in their twenties.
An increased risk was also noted in children born to mothers over the age of 40, with the risk increasing by 15% for mothers over 40 compared to children born to mothers in their twenties. Rates of autism also increased where both parents were older, and with parents who had a large age gap, with rates of ASD being highest when the father was between 35-44 with a partner who was 10 years younger or more.
Following these findings, the team then calculated which factors had the most influence, determining that parental age was the most significant, although age gaps also played a large part. Co-author of the study, Dr. Sven Sandin offered genetic mutations in sperm as an explanation for the higher risk of ASD with fathers over the age of 50, as hhis becomes more prevalent as men age. However, the reason for an increased risk of ASD with gaps in parental ages, or due to maternal age, still has no explanation.