Summary: According to a new study, siblings of children diagnosed with ASD or ADHD have an increased risk of being diagnosed with the disorders themselves. Researchers found the odds of being diagnosed with ASD were 30 times higher for those who had older siblings with autism, and 3.7 times higher for ADHD diagnosis.
Source: UC Davis.
Later-born siblings of children with autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD) are at elevated risk for both disorders, a new study led by Meghan Miller, assistant professor in the Department of Psychiatry and Behavioral Sciences and at the UC Davis MIND Institute, has concluded. The findings appear today in JAMA Pediatrics.
The study suggests that families who already have a child diagnosed with ASD or ADHD may wish to monitor younger siblings for symptoms of both conditions.
Symptoms of ADHD include difficulty focusing, nonstop talking or blurting things out, increased activity, and trouble sitting still. ASD, on the other hand, involves significant challenges with social interaction and communication, as well as the presence of unusual interests or repetitive behaviors like hand flapping or lining up objects.
“We’ve known for a long time that younger siblings of children with autism are at higher-than-average risk for autism, but the field didn’t have adequate data to tell whether they were at increased risk for ADHD,” said Miller. “Despite the fact that autism and ADHD appear very different in their descriptions, this work highlights the overlapping risk; younger siblings of children with ASD are at elevated risk of both ADHD and autism, and younger siblings of children with ADHD are at elevated risk not only for ADHD, but also for autism.”
Miller’s research team looked at medical records of 730 later-born siblings of children with ADHD, 158 later-born siblings of children with ASD, and 14,287 later-born siblings of children with no known diagnosis. Only families who had at least one younger child after a diagnosed child were included in the study.
“Evaluating recurrence risk in samples that include only families who have had an additional child after a diagnosed child is important because recurrence may be underestimated if researchers include families who decided to stop having children after a child was diagnosed with ASD or ADHD,” explained Miller.
Researchers found in the study that compared to later-born siblings of non-diagnosed children, the odds of an ASD diagnosis were 30 times higher in later-born siblings of children with ASD, and 3.7 times higher for a diagnosis of ADHD. Alternatively, compared to later-born siblings of non-diagnosed children, the odds of an ADHD diagnosis were 13 times higher in later-born siblings of children with ADHD whereas the odds of an ASD diagnosis were 4.4 times higher.
ADHD and ASD are believed to share some genetic risk factors and biological influences. This study supports the conclusion that ASD and ADHD are highly heritable and may share underlying causes and genetics.
Reliable recurrence risk estimates of diagnoses within the same disorder and across other disorders can aid screening and early-detection efforts and enhance understanding of potential shared causes of the disorders. The ability to diagnose ASD and ADHD early could improve both treatment and quality of life.
“There are reliable screening measures and practices for the diagnosis of autism in very young children,” Miller said. “Unfortunately, we don’t have any clinical standards or adequate tools for screening for ADHD at such young ages. We are currently working on identifying early markers of autism and ADHD in infants and toddlers who have an older diagnosed sibling, since these younger siblings are at elevated risk for ASD and ADHD.”
Other collaborating researchers included Erica D. Musser of Florida International University, Gregory S. Young at UC Davis, Brent Olson of the Marshfield Clinic Research Institute, Robert D. Steiner of the Marshfield Clinic Research Institute and University of Wisconsin, and Joel T. Nigg of Oregon Health & Science University.
Funding: This work was funded by the National Institute of Mental Health (R00 MH106642, R03 MH110812 and R37 MH059105).
Source: Dorsey Griffith – UC Davis
Publisher: Organized by NeuroscienceNews.com.
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Original Research: Open access research for “Sibling Recurrence Risk and Cross-aggregation of Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder” by Meghan Miller, PhD; Erica D. Musser, PhD; Gregory S. Young, PhD; Brent Olson, MA; Robert D. Steiner, MD; and Joel T. Nigg, PhD in JAMA Pediatrics. Published December 10 2018.
Sibling Recurrence Risk and Cross-aggregation of Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder
Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are believed to partially share genetic factors and biological influences. As the number of children with these diagnoses rises, so does the number of younger siblings at presumed risk for ADHD and ASD; reliable recurrence risk estimates within and across diagnoses may aid screening and early detection efforts and enhance understanding of potential shared causes.
To examine within-diagnosis sibling recurrence risk and sibling cross-aggregation of ADHD and ASD among later-born siblings of children with either disorder.
Design, Setting, and Participants
Using data extracted from medical records of 2 large health care systems in the United States, estimates of recurrence risk and cross-aggregation in later-born siblings of children with ADHD or ASD were compared with later-born siblings of children without these diagnoses. One data set included children seen between January 1, 1995, and December 31, 2013; the other included children born between January 1, 1998, and May 17, 2010. Participants included 15 175 later-born siblings of children with ADHD, ASD, and no known diagnosis. The study was conducted from October 2, 2017, to August 14, 2018.
Main Outcomes and Measures
Diagnoses of ASD or ADHD in the later-born sibling, ascertained from medical records, were the primary outcomes of interest; moderators included sex, gestational age, and maternal age.
A total of 15 175 later-born siblings were classified by familial risk status based on the older child’s diagnostic status: ADHD risk (n = 730; male [51.92%]), ASD risk (n = 158; male [48.10%]), and no known risk (n = 14 287; male [50.73%]). Compared with later-born siblings of children without ADHD or ASD, later-born siblings of children with ASD were more likely to be diagnosed with ASD (odds ratio [OR], 30.38; 95% CI, 17.73-52.06) or ADHD in the absence of ASD (OR, 3.70; 95% CI, 1.67-8.21). Compared with later-born siblings of children without a diagnosis, later-born siblings of children with ADHD were more likely to be diagnosed with ADHD (OR, 13.05; 95% CI, 9.86-17.27) or ASD in the absence of ADHD (OR, 4.35; 95% CI, 2.43-7.79).
Conclusions and Relevance
Later-born siblings of children with ASD or ADHD appear to be at elevated risk for the same disorder, but also of being diagnosed with the other disorder. These findings provide further support for shared familial mechanisms underlying ASD and ADHD, which may be useful for genetic and prospective developmental studies. Later-born siblings of children with ADHD or ASD should be monitored for both conditions.