Summary: New research indicates that 20% of children with an older sibling diagnosed with autism are also likely to be diagnosed with autism spectrum disorder (ASD), with this rate increasing to 36% when there are multiple siblings with ASD.
The study highlights that gender, race, and maternal education significantly affect the likelihood of autism recurrence in families. It also emphasizes the need for extra developmental monitoring and early intervention for families with autistic children.
This research underscores the importance of addressing disparities in healthcare access and support for all families affected by autism.
Key Facts:
- High Recurrence Rate: The study found that children with an autistic sibling have a 7 times higher chance of developing autism compared to the general population.
- Influence of Sex and Race: Younger siblings of female autistic children are more likely to develop autism (34.7%) than those of male autistic children (22.5%). Recurrence rates are higher in non-white families (25%) compared to white families (17.8%).
- Maternal Education Impact: Autism recurrence is 32.6% in families where the mother has a high school education or less, decreasing with higher maternal education levels.
Source: Kennedy Krieger Institute
A study conducted by top researchers, including those from Kennedy Krieger Institute, reveals that one in five children (20%) with an older sibling diagnosed with autism spectrum disorder (ASD) are likely to be diagnosed with the disorder as well.
Data show that when a child has more than one older sibling with autism, the family recurrence rate then rises to over 36%.
This research analyzed data from 1,605 infants with an older sibling with ASD. The infants were evaluated multiple times from ages 6 months through 36 months.
The study, conducted by organizations involved with the Baby Siblings Research Consortium, including Kennedy Krieger Institute, concluded that the rate of autism recurrence is seven times higher in families with an autistic child compared to the general population.
This finding is in line with earlier research, but investigators said this new study used more comprehensive reporting strategies.
Dr. Rebecca Landa, PhD, CCC-SLP, serves as the Vice President and Executive Director for the Center for Autism Services, Science, and Innovation (CASSI) at Kennedy Krieger and was involved in this research. She says the findings show the importance of extra developmental monitoring for babies born into families with autistic children.
“Pediatricians and family members have to keep a diligent eye on infants born into families with an already diagnosed autistic child,” Dr. Landa said. “Early referral for diagnostic evaluation is crucial to ensure support, resources, and intervention.”
The study found that the sex of a child significantly influences the chance of recurrence. Younger siblings of female autistic children were more likely to develop autism (34.7%) compared to siblings of males (22.5%). Male younger siblings also had a higher likelihood of being autistic than females.
Additionally, the study found the reoccurrence of ASD in white families was 17.8%, while it increased to 25% across other races collectively.
“The scale and diversity of this group of infants, compared to our prior recurrence rate study published over a decade ago, gives strong evidence that these recurrence rates are reliable,” Dr. Landa said. “We need to update recurrence studies like these due to the population increase in autism prevalence over the years. We know so much more now in 2024 than we did in 2011.”
Maternal education also showed a significant effect on ASD recurrence rates. The study reported a higher recurrence rate of 32.6% for mothers with a high school education or less. That percentage decreases for mothers who obtained a college degree and/or a graduate degree. It was also noted that this effect was significant only for mothers and not for fathers.
Researchers say the prevalence of autism has risen to 1 in 36 children over the last decade. They attribute this increase to improved awareness of autistic females and cognitively able/verbal children, rather than a true rise in autism rates.
The study strengthened its findings by using diagnoses only from ASD experts, eliminating biases associated with parent interviews. Additionally, new diagnostic criteria have enhanced the strength of these findings.
Dr. Landa notes that the study’s findings reveal how factors such as race, sex, education, and healthcare access influence the timeliness of diagnoses and support. She emphasizes the need for improved efforts to address disparities as we continue to learn more about ASD.
“It’s crucial that we ensure families facing social inequities have access to resources, education, and providers,” Dr. Landa said. “Every single child with autism and their family deserve this support.”
About this autism research news
Author: Jessica Gregg
Source: Kennedy Krieger Institute
Contact: Jessica Gregg – Kennedy Krieger Institute
Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Familial Recurrence of Autism: Updates From the Baby Siblings Research Consortium” by Rebecca Landa et al. Pediatrics
Abstract
Familial Recurrence of Autism: Updates From the Baby Siblings Research Consortium
OBJECTIVES
Autism spectrum disorder (ASD) is estimated to be ∼10 times higher in children with versus without an autistic sibling in population-based studies. Prospective studies of infant siblings have revealed even higher familial recurrence rates. In the current prospective longitudinal study, we provide updated estimates of familial ASD recurrence using a multinational database of infants with older autistic siblings.
METHODS
Data were collated across 18 sites of the Baby Siblings Research Consortium, an international network studying the earliest manifestations of ASD. A total of 1605 infants with an older autistic sibling were followed from early in life to 3 years, when they were classified as ASD or non-ASD. Hierarchical generalized linear modeling, with site as a random effect, was used to examine predictors of recurrence in families and calculate likelihood ratios.
RESULTS
A total of 20.2% of siblings developed ASD, which is not significantly higher than the previously reported rate of 18.7%. Male infant sex and >1 older affected sibling were significant predictors of familial recurrence. Proband sex also influenced recurrence rates, with siblings of female probands significantly more likely to develop ASD than siblings of male probands. Race and maternal education were also associated with recurrence in families.
CONCLUSIONS
The familial recurrence rate of ASD, as measured in infant sibling studies, has not changed appreciably since previous estimates were made in 2011. Younger siblings of autistic children, particularly those who are male, have an affected female sibling, multiple affected siblings, or are impacted by social inequities, should be closely monitored and promptly referred for diagnostic evaluation.
