A recent study has reaffirmed previous research showing that siblings of autistic children have a 20% chance of being autistic themselves, which is significantly higher compared to infants without autistic siblings.
This finding comes from a study led by Sally Ozonoff from the UC Davis MIND Institute in collaboration with the Baby Siblings Research Consortium, which involves over 20 research groups from universities worldwide.
Ozonoff, a renowned professor in Psychiatry and Behavioral Sciences, has dedicated years to studying the recurrence of autism within families.
The research, published in Pediatrics, is based on a large and diverse group of families from research sites across the US, Canada, and the UK, mirroring the consortium’s 2011 findings on autism likelihood in siblings.
Responding to Increasing Autism Rates
The study addresses the upward trend in autism diagnoses, with current estimates suggesting that 1 in 36 children has autism, a significant increase from 1 in 68 back in 2011 as per the Centers for Disease Control and Prevention.
Ozonoff underlines the changes in diagnostic criteria and a better awareness of autism in girls over the past decade, prompting the need to analyze how these factors impact autism recurrence in families.
While the 2011 study reported an 18.7% recurrence rate, the recent study found a slightly higher rate at 20.2%, a change considered not statistically significant.
Expanded and Diverse Research
The study incorporated data from 1,605 infants across 18 research sites, all with an older autistic sibling.
Ozonoff notes that this study is notably more extensive and includes a more diverse pool of participants compared to the original study involving 664 children.
Researchers followed these infants from as early as 6 months up to seven visits, assessing them for autism at age 3 through the Autism Diagnostic Observation Schedule (ADOS-2).
Factors Influencing Autism Recurrence
The study reveals that the sex of the first autistic child significantly influences the likelihood of autism recurrence within a family.
Families with an autistic daughter as their first child have a 50% higher chance of having another child with autism compared to families with an autistic son.
Moreover, having multiple autistic siblings increases the likelihood of autism in a child to 37%, compared to 21% with only one autistic sibling.
Additionally, the gender of the infant also plays a role, with boys being almost twice as likely as girls to be diagnosed with autism.
Race and Maternal Education Impact
The study suggests that race and the mother’s education level are potential influencing factors. Non-white families exhibit a higher recurrence rate at 25% compared to white families at 18%.
The recurrence rates also vary based on the mother’s education level, ranging from 32% for those with a high school education or less to 16.9% for those with a graduate degree.
Ozonoff stresses the importance of replicating these findings, noting their alignment with recent CDC data indicating higher autism prevalence in historically underrepresented groups.
These insights may signal social determinants impacting autism rates, but further research is needed to explore this aspect in depth.
Monitoring and Support
The researchers emphasize the significance of closely monitoring siblings of autistic children for developmental delays in social and communication skills, especially in families with limited access to care, as early diagnosis and intervention are crucial.
Additional Contributors:
The study included contributions from various researchers including Gregory Young and Rebecca Schmidt from UC Davis, Jessica Bradshaw from the University of South Carolina, Tony Charman from Kings College London, Katarzyna Chawarska from Yale University, and others from prestigious institutions.
