Term vs. preterm birth and the presentation of autism

The paper by Katherine Bowers and colleagues [1] continues the interest in the concept of 'the autisms' with their observations on the presentation of autism (and its comorbidities) when looking at those "born preterm versus those born at term".

We'd better get back, 'cause it'll be dark soon,
and they mostly come at night... mostly

Based on an analysis of quite a healthy participant number heading up to 900 "males and females with autism spectrum disorder", authors reported on several phenotypic differences between the 13% born preterm compared to the majority born following a full-term pregnancy. These differences, also influenced by gender, were in core areas such as language skills and the presence of comorbidities such as sleep apnea and attention-deficit hyperactivity disorder (ADHD). The authors conclude that their results "may have implications for understanding the underpinnings of a subset of individuals with autism spectrum disorder and contribute to the development of focused treatments for autism spectrum disorder among children born preterm".

Whilst one should always be a little cautious about making too much of any specific link with something like preterm birth (see here to illustrate the many and varied outcomes following this variable) I was interested in the Bowers' results. I think back to similar research into autism subgroups from Unwin and colleagues [2] (talked about in a previous post) describing how low birth weight was "associated with greater sleep disturbances".

Although many variables can affect foetal growth measures, preterm birth can adversely impact on birth weight and with that, one might see a possible common feature appearing in relation to issues at birth. That being said, the strength of any association between preterm birth and something like the comorbid presence of ADHD in cases of autism is likely to be a complex issue as per the findings from Harris and colleagues [3] who concluded that in the general population: "former late preterm infants have similar rates of LD [learning disabilities] and ADHD as term infants".

Bowers et al also took into account a role for gender in their results, reporting that there may be more to see here. Although quite an obvious variable to look at when it comes to autism (see here), there is perhaps not as much appreciation of how sex might link into autism phenotypes as one might imagine. Recently, Reinhardt and colleagues [4] did venture into this area, concluding that whilst they did not see any "significant effects of sex or a diagnostic group by sex interaction" when it came to autism presentation, further research is indicated in this area. I might add that such investigations might also wish to look further at comorbidity too, or autism plus [5] if you like.

Music to close and Bulletproof by La Roux.

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[1] Bowers K. et al. Phenotypic differences in individuals with autism spectrum disorder born preterm and at term gestation. Autism. 2014 Sep 5. pii: 1362361314547366.

[2] Unwin LM. et al. A "bottom-up" approach to aetiological research in autism spectrum disorders. Front Hum Neurosci. 2013 Sep 19;7:606.

[3] Harris MN. et al. ADHD and learning disabilities in former late preterm infants: a population-based birth cohort. Pediatrics. 2013 Sep;132(3):e630-6.

[4] Reinhardt VP. et al. Examination of Sex Differences in a Large Sample of Young Children with Autism Spectrum Disorder and Typical Development. J Autism Dev Disord. 2014 Sep 5.

[5] Gillberg C. & Fernell E. Autism Plus Versus Autism Pure. J Autism Dev Disord. 2014 Jun 24.

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Bowers K, Wink LK, Pottenger A, McDougle CJ, & Erickson C (2014). Phenotypic differences in individuals with autism spectrum disorder born preterm and at term gestation. Autism : the international journal of research and practice PMID: 25192860