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Spectrum: Autism Research News

News The latest developments in autism research.

Community Newsletter: Late-emerging autism, validation of subtypes, litter effect

by  /  2 May 2021
Speech bubble formed by a network of communication

Illustration by Laurène Boglio

Hello, and welcome to the Community Newsletter! I’m your host, Chelsey B. Coombs, Spectrum’s engagement editor.

Before we get into the meat of this week’s newsletter, we want to let you know that we will be covering the International Society for Autism Research conference virtually next week and want to hear your thoughts on it. What sessions are you most excited about? Tweet us @spectrum or email [email protected].

Our first tweet this week comes from Lucy Livingston, lecturer in psychology at Cardiff University in the United Kingdom, about a new paper published in the American Journal of Psychiatry: “Variable emergence of autism spectrum disorder symptoms from childhood to early adulthood.”

The researchers used data from the Avon Longitudinal Study of Parents and Children cohort in the U.K. They analyzed children’s scores at age 7, 10, 13, 17 and 25 on the Social and Communication Disorders Checklist, a parent questionnaire that screens for autism traits.

From these data, the researchers categorized the children by their trait trajectories. Almost 89 percent fell into a ‘low trajectory’ group that showed few autism traits at any point in time. A ‘declining trajectory’ group, which made up 5 percent of the cohort, showed more autism traits during childhood than later on. The remaining 7 percent followed a third, ‘late-emerging trajectory,’ with few autism traits in childhood but an increase throughout adolescence and adulthood.

“[The findings] also challenge our current understanding that ASD symptoms invariably manifest early in development,” the researchers wrote.

People in the late-emerging trajectory group showed more neurodevelopmental challenges in childhood than did those in the low-trajectory group, the team also found. They hypothesize that those children camouflaged their traits, “perhaps as a result of accommodating environments, scaffolding by families, or individual characteristics that enabled them to compensate during this developmental period, but that with increasing demands on social skills with age, social difficulties became more apparent.”

Meng-Chuan Lai, assistant professor of psychiatry at the University of Toronto in Canada, tweeted that the study was “food for thought about what Neurodevelopmental Conditions entail and how they manifest.”

Hywel Williams, senior lecturer in bioinformatics at Cardiff University, wrote that the study “expand[s] our understanding of when autism symptoms first manifest.”

Tinca Polderman, associate professor of child and adolescent psychiatry at Vrije Universiteit Amsterdam in the Netherlands, wrote that this late-emergence trajectory is also seen in the Netherlands Autism Register.

Our next thread comes from Hilde Geurts, professor of clinical neuropsychology at the University of Amsterdam in the Netherlands, who has a new paper in Clinical Psychology Review called “Validation strategies for subtypes in psychiatry: A systematic review of research on autism spectrum disorder.”

The team reviewed 156 papers published since 2000 that looked at creating subgroups of autistic people and recommended using the SUbtyping VAlidation Checklist (SUVAC) to validate such results.

In her thread, Geurts highlighted the seven strategies in the SUVAC process.

The review found that the majority of the subgrouping papers had been published after 2016 and that 82 percent found two to four subtypes of autism.

“We hoped when starting this endeavour that we could draw conclusions for which subgroups there is clear evidence that they are indeed sufficiently valid & of use for clinical practice…but we couldn’t,” Geurts tweeted.

Michelle Dawson, an autism researcher at Hôpital Rivière-des-Prairies in Montreal, Canada, tweeted that it was a “timely, thoughtful, thorough, extremely useful systematic review.”

Marita Cooper, a postdoctoral researcher at the Children’s Hospital of Philadelphia in Pennsylvania, tweeted, “Interesting thread on standardizing processes for examining psychiatric subtypes.”

Eiko Fried, associate professor of clinical psychology at Universiteit Leiden in the Netherlands, also wrote a thread about the research, in which he discussed what he views are problems with subtyping research.

Fried cites a number of issues within the statistical modeling itself, as well as “Problematic reification of subtypes; people often give these subtypes names (e.g. “melancholic” or “atypical” depression), when the empirically derived subtypes have little to do with these theoretical ideas.”

Finally, we wanted to highlight a Spectrum opinion article by Jessica Jiménez and Mark Zylka that got a lot of attention this week on social media: “Few autism researchers control for the ‘litter effect’ — this needs to change.”

Because animals within a litter are more similar to one another than animals between litters, researchers will get skewed results if they try to increase their sample size by using many animals from a small number of litters.

“We hope that our article will bring greater awareness to the litter effect and help scientists appropriately design future studies to minimize the impact of litter-to-litter variation in rodent models of autism,” Jiménez and Zylka wrote.

Uri Kahanovitch, a postdoctoral researcher at the University of Western Ontario in Canada, said, “This is an important read, not just autism researchers, but for all who do research on rodents.”

Amy Ryan, a postdoctoral researcher at the University of California, Davis, replied, “Siblings lived in the womb together and will be more similar to each other than others no matter the experimental design, and we need to account for that!”

Will Kenkel, assistant professor of psychological and brain sciences at the University of Delaware in Newark, talked up using voles in research to avoid the litter effect.

That’s it for Spectrum’s Community Newsletter this week. If you have any suggestions about interesting social posts you have seen in the autism research sphere, feel free to send an email to me at [email protected] See you next week!