Illustration of hybrid objects: part light bulb, part lab vial, some in blue and some in red to signify null and replicated results
Illustration by Laurène Boglio
Illustration by Laurène Boglio

Null and Noteworthy: Autism and aging, anorexia overlaps, pregnancy effects

In this edition of Null and Noteworthy, researchers replicate encouraging findings on autism and aging and shoot down a host of potential links between pregnancy complications and having a child with autism.

By Laura Dattaro
10 February 2022 | 5 min read

As Null and Noteworthy enters its second year, I’m refocusing on its purpose — and I came across the perfect tweet to express it, courtesy of University of Westminster psychologist Samuel Westwood:

Fortunately, many replications and null findings are making their way into journals — so many, in fact, that this newsletter will now be published monthly, rather than every other month. So keep an eye out for the next edition in March. In the meantime, thanks, as always, for your feedback, and please continue to send your thoughts, ideas, interesting studies and cat photos to [email protected].

Aging up:

Though much autism research focuses on early development, scientists are increasingly working to understand how the brain may age differently in autistic and non-autistic people. A new study set out to replicate a pair of findings from 2015 and 2016. Both found that autistic adults lost many cognitive faculties at the same rate as non-autistic adults but retained more of their working and visual memory and ability to intuit others’ feelings, suggesting that autism has a ‘protective effect’ on aging.

Not so, according to the new study, which looked at 88 autistic and 88 non-autistic people between 30 and 89 years of age and was led by one of the co-investigators of the 2015 work. The team replicated nearly all of the previous findings — suggesting that autistic adults are not at any increased risk for cognitive difficulties as they age — but saw no evidence of the previously observed protective effect.

The work was published in Autism Research in December.

Autism and anorexia:

People with anorexia nervosa are much more likely to be autistic, have autism traits or give birth to an autistic child than people without the eating disorder. But the reasons underlying the overlap are murky, and the extent to which autism predisposes a person to anorexia is far from clear. Some findings have suggested that a reduced interest in socializing is a common heritable trait in both conditions, but new data contradict that idea.

Researchers showed a film clip to 93 autistic people, 43 people with anorexia and 106 controls while tracking where on the screen the participants directed their gaze. While autistic people looked at faces less than controls did, people with anorexia did not. And in neither the autism nor anorexia groups were autism traits associated with attention to faces. Paying less than the typical amount of attention to faces could underlie some social difficulties in autistic people, but that mechanism doesn’t seem to be at play in people with anorexia, the team concluded.

The findings were published in Autism in November.

Pregnancy probes:

Many factors are theorized to influence autism likelihood prenatally, but a pair of new studies tentatively rule out two. In one, researchers asked the mothers of 1,428 children whether they had used marijuana at any point in their pregnancy or in the three months prior. Though the prevalence of autism was slightly higher in children whose mothers had used the drug — 5.2 percent — than in those who hadn’t — 4.4 percent — there were no differences in autism likelihood between the groups after accounting for the mother’s education level and use of tobacco or alcohol. The other study, which looked at more than 4 million children born in Denmark, Finland, Iceland, Norway or Sweden from 1996 to 2017, found no association between a mother’s use of antipsychotics during pregnancy and the chances of autism or attention deficit hyperactivity disorder in her child.

The marijuana findings were published in the Journal of Autism and Developmental Disorders in November; the antipsychotics study appeared in Evidence-Based Mental Health in November.

Et al.:

  • Trouble gaining weight in infancy is not associated with autism or attention deficit hyperactivity disorder, though it does appear to be linked to motor delays and intellectual impairments. European Child & Adolescent Psychiatry
  • Neither a woman’s nor her child’s genetic risk for rheumatoid arthritis influences the child’s chances of being autistic, despite observations of an elevated autism prevalence among children born to women with the autoimmune condition. Translational Psychiatry
  • Alexithymia — an inability to interpret one’s own emotions — doesn’t appear to influence quality of life in autistic people, according to a new study, though this null finding is likely due to low statistical power and the pandemic lockdowns, which lowered quality-of-life scores for autistic and non-autistic people alike, the researchers write. Research in Autism Spectrum Disorders
  • A mother’s placental health and structure, including placenta weight, umbilical cord length and inflammation, are not associated with the likelihood of autism in her child. Autism Research
  • A massive United Kingdom population study found that autism — alone among neuropsychiatric conditions in general — is not associated with a higher risk of self-harm or suicide, contradicting much other research on the subject. The Journal of Child Psychology and Psychiatry
  • And finally, a possible conclusion to an ongoing Null and Noteworthy saga: A fifth study has found no association between labor epidurals and autism, prompting an accompanying editorial to conclude that there is now “sufficiently robust” evidence that the two are not linked. British Journal of Anaesthesia