Middle ear infection and autism (again)

"Autism was more common in children who had had an otitis media infection or who had been treated with antibiotics."

Minus any sweeping generalisations, that was the conclusion reached in the study by Theresa Wimberley and colleagues [1] continuing some important research themes (see here and see here) examining any "interplay among otitis media, antibiotics, and the subsequent risk of developing autism."

Just in case you don't already know, otitis media infection refers to an infection of the middle ear that "causes inflammation (redness and swelling) and a build-up of fluid behind the eardrum." Aside from the use of painkillers, the seriousness of certain otitis media infections can sometimes mean that antibiotics are prescribed to combat any underlying bacterial infection or even in some cases, grommets inserted as treatment.

Wimberley et al report results based on "the entire Danish population", well, over three-quarters of a million children "followed from birth (January 1, 1997 to December 31, 2008) until December 31, 2012." They calculated various 'risk of autism' statistics as a function of a previous medical diagnosis of otitis media and "antibiotic prescriptions redeemed at Danish pharmacies." Yes folks, yet again those big data Scandinavian population registries have been used to good research effect.

Results: "The absolute risk of autism before age 10 was increased among children with otitis media (1.2% for females and 3.3% for males) and in children who had redeemed an antibiotic prescription (0.6% and 2.7% for females and males) compared to children without a history of otitis media and antibiotics usage (0.4% for females and 1.9% for males)." Researchers also reported finding "little evidence of a synergistic effect between otitis media infections and treatment with antibiotics" despite them being over-represented in relation to autism. They also caution that cause-and-effect cannot be inferred from their observational results.

What more can one say about the Wimberley findings? Well, echoing the idea that correlation is not the same thing as causation, I'd say that there is quite a bit more research to do on this topic. Further investigations are required into the possible mechanisms through which autism may manifest at least partially as a result of a history of ear infection (or indeed vice-versa). Mention of antibiotics also brings in areas of additional research interest such as the gut microbiome and what antimicrobials might 'be doing' to the trillions of passengers that are carried in the deepest, darkest recesses of the human body. I'm also minded to suggest that alongside antibiotic use to potentially treat infections like otitis media, researchers might also want to focus in on other medicines that might be accessed in such case such as over-the-counter pain relief in light of other *associations* that have been made (see here).

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[1] Wimberley T. et al. Otitis media, antibiotics, and risk of autism spectrum disorder. Autism Res. 2018 Oct 3.

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Middle ear infections and autism

I'm gonna be fairly brief today in drawing your attention to the paper published by Daniel Adams and colleagues [1] reporting that: "Children with ASD [autism spectrum disorders] are more likely to have middle ear infections and otitis-related complications."

The results, which we've known were coming (see here), detail findings based on a retrospective case-cohort study where the health insurance records of children of US military families were initially screened for the presence of autism or an ASD and then further screened for ICD-9-CM diagnostic codes relevant to acute otitis media and related diagnoses. The supplementary material provided alongside the article gives further details (see here).

Alongside the findings of an elevated rate of acute otitis media (AOM) among children diagnosed with autism were various other details including a higher rate of complications following AOM such as mastoiditis - affecting the mastoid bone behind the ear - and the requirement for a mastoidectomy. The surgical reconstruction of the eardrum (tympanoplasty) was also more frequently noted for the autism group versus the non-autism controls. The authors conclude that quite a bit more research is required in this area alongside "highlighting the importance of routine middle ear examinations and close attention to hearing impairment in this population."

This is interesting work. For many years I've heard about how quite a few children on the autism spectrum had a history of early ear infections that were typically followed by quite an aggressive schedule of antibiotic use. Indeed, on one of the previous blogging occasions when I've mentioned ear infections and autism it was to speculate on the double-edged sword that might be the [early repeated] use of antibiotics with [some] autism in mind (see here). That 'association' remains as relevant today as it did during earlier descriptions [2] playing into the various emerging gut bacteria studies of autism.

I have only a few more things to add. First is the idea that screening for middle ear infections might be an important issue for children on the autism spectrum. I can't argue with that; and indeed added to the requirement for screening other sensory gateways such as the eyes (see here), the evidence is accumulating for preferential services to be offered. Second is the idea that recurrent otitis media might show some connection with aspects of sleep too [3] such that issues such as sleep apnoea occurring alongside autism (see here) might also be something to look out for. Finally is the need for quite a bit more research on what happens to autistic symptoms when ear infections are finally diagnosed and treated. Take for example the case report detailed by Kazuhiro Tajima-Pozo and colleagues [4] and the suggestion that surgical correction of the "middle ear for repetitive otitis" correlated with "an improvement in autistic behaviours". One wonders how many other children have shown or might show similar effects and what the possible mechanism(s) could be...

Music: Alanis Morissette - Ironic.

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[1] Adams DJ. et al. Otitis Media and Related Complications Among Children with Autism Spectrum Disorders. J Autism Dev Disorders. 2016. Jan 6.

[2] Bolte ER. Autism and Clostridium tetani. Med Hypotheses. 1998 Aug;51(2):133-44.

[3] Gozal D. et al. Prevalence of Recurrent Otitis Media in Habitually Snoring School-Aged Children. Sleep medicine. 2008;9(5):549-554.

[4] Tajima-Pozo K. et al. Otitis and autism spectrum disorders. BMJ Case Rep. 2010 May 6;2010. pii: bcr1020092351.

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Adams, D., Susi, A., Erdie-Lalena, C., Gorman, G., Hisle-Gorman, E., Rajnik, M., Elrod, M., & Nylund, C. (2016). Otitis Media and Related Complications Among Children with Autism Spectrum Disorders Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-015-2689-x