Children who have a big brother or big sister with an autism spectrum disorder face an increased risk of developing such a disorder themselves, according to a new study in the journal JAMA Pediatrics. The study, of more than 1.5 million children in Denmark, found that sibs of kids diagnosed with autism had an almost seven-fold increased risk of developing autism as well.
For parents, the findings raise difficult questions about how proactive they should be in screening for the disease among their younger children if older siblings are affected. Alycia Halladay, senior director, environmental and clinical sciences for Autism Speaks, says parents who have already had a child diagnosed on the spectrum should alert their doctor to the family history. During check-ups, when a doctor asks about inherited disorders like cystic fibrosis, they now typically include autism on the check-list.
Mothers of autistic children can also take steps during pregnancy to lower the risk of autism in their next offspring, such as taking prenatal folic acid and avoiding overexposure to toxins. That attention could even extend to the infants' first few years, since studies suggest that some intensive behavior therapies can help to mitigate the symptoms of autism. "We know that early intervention can make a real lifetime of difference. So be very vigilant during that child's life, all the way from birth to the well baby check-ups, six months, 12 months, and 18 months," says Halladay. "Make sure you are watching for the signs and symptoms of autism. Consult your pediatrician, and if you do notice the signs and symptoms of autism you can receive help free of charge from a state-based early intervention agency."
Researchers are also developing tests that can detect the genetic risk factors associated with the disorder, and more of these biomarkers may become available as additional gene-based contributors emerge. Scientists from University of Utah and the Children's Hospital of Philadelphia, for example, recently identified 24 new gene variants associated with autism spectrum disorders in January.
Image: Toddler and baby, via Shutterstock