According to a new study of the Yale Child Study Center, children who have an older sibling with autism spectrum disorder (autism) are at greater risk of developmental vulnerabilities if they also have other relatives with neurodevelopmental or psychiatric conditions.
Effects on siblings of children with autism
Researchers found that siblings of autistic children had increased severity of social and communication difficulties, common in autism, if they had relatives with conditions such as schizophrenia or anxiety. Family histories of anxiety and intellectual disability were also associated with poorer verbal and nonverbal skills and less developed adaptive skills in siblings who participated in the study, according to research published June 19 in the journal Autism Research.
These findings may help pediatricians identify newborn siblings of children with autism who may be at increased risk for developing future developmental problems.
“We are always looking for information to help us monitor and support the development of infants with known risk factors for developmental disorders. Family history information is available at birth and can guide parents and professionals in their developmental monitoring efforts,” said Katarzyna Chawarska, Emily Fraser Beede Professor of Child Psychiatry at Yale School of Medicine and lead author of the study.
“Considering family history of these disorders may enhance efforts to predict long-term outcomes in younger siblings of children with autism and provide insight into factors that contribute to the variable phenotypic outcomes in this cohort.”
![Autism, Scientific Hoaxes](https://tech.icrewplay.com/wp-content/uploads/2023/04/Autismo-approvato-Piano-regionale-ridotta-1024x683.jpg)
The study team, led by Chawarska, collected information on the family history of the parents of 229 younger siblings of children with autism between March 2006 and May 2022. The siblings participated in a comprehensive assessment of social, cognitive, language, and adaptive skills.
The researchers studied whether family history of neurodevelopmental and psychiatric conditions was related to developmental outcomes of younger siblings of children with autism, taking into account variables such as the child’s birth year, age, sex assigned at birth, and family demographics.
Autism is a neurodevelopmental condition characterized by social and communication deficits, as well as sensory sensitivities, repetitive behaviors, and stereotyped interests. Past research has shown that younger siblings of children with autism have a wide range of developmental problems in social, cognitive, language, and adaptive areas.
Symptoms in some siblings are severe, span multiple domains, and lead to a diagnosis of autism, while in others they may be milder or present in only a few developmental areas. Many siblings progress to typical development.
“It is unclear what causes such heterogeneity in outcomes in younger siblings of children with autism,” Chawarska said. “Identifying factors linked to variable outcomes is essential to improving our understanding of their underlying biology and identifying vulnerable siblings early.”
![Autism](https://tech.icrewplay.com/wp-content/uploads/2023/06/Autismo-1.jpg)
As in previous studies, the researchers found a high prevalence of neurodevelopmental and psychiatric disorders in first-, second-, and third-degree relatives of children with autism. According to Chawarska, the most common conditions among relatives included anxiety disorders, schizophrenia, bipolar disorder, depression, attention-deficit/hyperactivity disorder, language delays, and intellectual disability.
“Future studies will be needed to clarify the mechanistic foundations of the observed associations between family history and developmental outcomes,” Chawarska noted.
However, despite the lack of clarity regarding the mechanisms underlying the observed effects, this research suggests that family history of certain psychiatric and developmental disorders signals greater developmental vulnerability in younger siblings.
The extent of developmental delays varies with autism
According to a study published online in JAMA Pediatrics, the developmental progress of autism varies greatly across different conditions.
Susan S. Kuo, Ph.D., of the Broad Institute of MIT and Harvard in Cambridge, Massachusetts, and colleagues assessed variability in the ages at which individuals with autism reach developmental milestones. The analysis included 17,098 individuals with autism and 4,145 siblings without a diagnosis of autism (aged 4 to 17 years).
The researchers found that individuals with autism showed delays in reaching milestones compared to their unaffected siblings, with average delays ranging from 0.7 to 19.7 months. The presence of a co-occurring intellectual disability, a rare genetic variant associated with neurodevelopmental disorder, and a diagnosis of autism by 5 years of age were associated with more severe and more variable delays in autism.
![Repetitive behaviors](https://tech.icrewplay.com/wp-content/uploads/2022/08/autismo_peluche.jpg)
An association between more severe and more variable delays and membership in earlier study groups was also found, consistent with the expansion of autism diagnosis and assessment over the past 30 years.
“As the largest summary to date of developmental milestones in autism, to our knowledge, this study demonstrates substantial developmental variability across conditions and provides important context for understanding the phenotypic and etiological heterogeneity of autism,” the authors write.
Family Issues in Autism Outcomes
Researchers have found that cognition is affected by siblings. Autistic children with autistic siblings have better cognition than those who are the only family members with the condition, researchers have found. It is important to note that the outcome is not dependent on birth order.
Although previous studies have shown that having autistic siblings leads to better cognitive abilities in individual children with the condition, it was hypothesized that the order in which the children were born was a significant factor.
“Until now, it was thought that second-born autistic children had better cognitive abilities because their parents already had experience and adapted their approach accordingly,” says Dr Lauren Lawson of the Olga Tennison Autism Research Center at La Trobe University.
However, new research by Dr. Lawson and her team has shown that even firstborn autistic children with younger siblings with the disorder fare better than those with no affected relatives.
![Orbit, children with autism](https://tech.icrewplay.com/wp-content/uploads/2022/09/Come-riconoscere-lautismo-nei-bambini-1024x682.jpg)
“This is an exciting discovery, because it reinforces the growing consensus that there are distinct subtypes of autism,” he says.
Autism spectrum disorder affects up to 2% of the population, but has several variants. It can occur in just one child among siblings, or in all, or most, of them.
Understanding why this happens has long been a key research goal for scientists.
“Examining the differences between these families is critical because most of our knowledge about the development of autism in the early years of life is based on families with multiple children with autism,” says Dr. Lawson.
“These families represent only a fifth of the autistic population, which calls into question the validity of this knowledge for the majority of autistic individuals.”
Understanding autism in women
Autism affects about one in 100 Australians and costs about $10 billion a year. But according to Chancellor’s postdoctoral researcher Rachel Grove, there’s still a lot we don’t know, particularly when it comes to women.
Although autism affects both genders, Rachel says, “Autism has been diagnosed at a rate of about four males to one female, so it has historically been understood through that male lens. Current research is showing that there may be almost as many autistic females as males, but we simply don’t know enough about them.”
Rachel’s interest in autism began 10 years ago, when she was studying for her degree. “I started working with families with disabilities, especially families with autistic children, and it just grew from there,” she says.
Over the past four years, through her clinical practice, Rachel has also spent a lot of time working with autistic adults, primarily autistic women.
Autism is characterized by social and communication difficulties, as well as repetitive behaviors, sensory sensitivities, and special interests. But, Rachel says, there are many “subtle differences” between autistic men and women. For example, some women may exhibit fewer social communication difficulties than men.
![FXS, SACS-R, autism](https://tech.icrewplay.com/wp-content/uploads/2021/05/baby-sitter-per-bambini-con-autismo-1024x683.jpg)
“It could be that autistic women have developed skills to deal with some of these challenges,” Rachel says. “These strengths can make it difficult to identify autistic women.”
Rachel also states that most of the tools used to measure, assess, and diagnose autism have been created using male samples. This, she says, can leave autistic women further disadvantaged and entering adulthood misdiagnosed or undiagnosed.
That’s why, through her research, Rachel hopes to establish better methods for assessment and diagnosis that take into account the differences between autistic men and women. Using existing large datasets and participatory research with autistic individuals, her research will seek to understand some of the unique strengths and challenges experienced by autistic women, particularly in special interests, repetitive behaviors and sensory challenges.
Importantly, her research will look at how these differences might relate to outcomes such as mental health and wellbeing. It is hoped that this will lead to earlier and more accurate diagnosis for autistic girls and women. Rachel says: “Especially for autistic adults, the diagnosis is really important, as it is part of their identity.
“I have always admired the strength and resilience of all the families and people I have worked with.
“I think having a daughter makes me feel more passionate about wanting to make some changes in society. I want to make sure she can grow up in a world where people are fair.”
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