Autism Risks For Siblings
A new study in the US has reported some interesting findings for parents who already have a child on the autistic spectrum. Previous studies indicated there was between 3% and 10% risk of having a second child being diagnosed with ASD if there was an older sibling with the condition. However these past studies were limited by small sample sizes and other factors.
The results published this week by the American Academy of Pediatrics took a much larger sample (664 children) from an average of 8 months on to 36 months at which time they were assessed by an “expert clinician” as either having autism or not having autism.
The researchers found there was an 18.7% likelihood that a child with an older sibling with ASD would also develop ASD. That is significantly higher than previously thought. Where there was more than one older sibling with ASD the risk further increased to 32%! There was a significantly greater risk in boys compared with girls. The gender, age or severity of the ASD in the older sibling did not affect the likelihood of the younger sibling being diagnosed on the spectrum.
This is probably not what you want to read if you’ve a child on the spectrum and you’re contemplating a larger family. I think the increase is partly due to the increased sample size and improved sampling methods; but also to the fact that we now have a much wider definition of autism compared with the earlier studies that were carried out in the 1980s and 90s. The researchers also point out that:
Many families actually believe that the risk to later-born siblings is higher [my emphasis] than either the current investigation or previous studies suggest it to be.
So it’s important that up to date information is made available to parents. You can read the report in full at Recurrence Risk for Autism Spectrum Disorders: A Baby Siblings Research Consortium Study