Wednesday 17 October 2018

"maternal pre-pregnancy obesity is associated with autism-like behaviors in offspring"

The results reported by Kandice Varcin and colleagues [1] concluding that "maternal pre-pregnancy obesity is associated with autism-like behaviors in offspring" continue and extend a research theme (see here and see here). A research theme that highlights a potentially important relationship between maternal weight (and/or related parameters) and offspring development across various, potentially intertwined, variables (see here).

Including the notable name of Andrew Whitehouse on the authorship team (see here and see here for some examples of his other research), researchers set about to explore whether "pre-pregnancy weight was related to autistic-like traits among offspring not diagnosed with ASD [autism spectrum disorder]." I added the bold highlight to the word 'not' to emphasise how this work was set slightly apart from the other research that has observed an *association* between maternal weight before or during pregnancy and a risk of a formal diagnosis of autism in offspring. Pregnant women in their second trimester of pregnancy were recruited and "had their height measured." They also "reported their pre-pregnancy weight" which combined with the height measurements to give the measure known as the body mass index (BMI). And also: "At 19-20 years of age, 1238 offspring of these women completed a measure of autistic-like traits, the Autism-Spectrum Quotient (AQ)." Keep those issues in mind for now.

Results: "Regression analyses identified a positive association between increasing maternal pre-pregnancy BMI and increasing AQ Total Score amongst offspring; this association was maintained even after controlling for a range of variables including maternal/obstetric factors (age at conception, education, smoking, alcohol consumption, hypertensive diseases, diabetes, threatened abortion), paternal BMI at pregnancy, and child factors (parity, sex)." Sorry for the large quote, but the authors said it better than I ever could. Authors also reported that those women defined as being obese before pregnancy, according to their BMI measurement, were quite a bit more likely to "have offspring with high scores (≥26) on the AQ." This then lead them to conclude that "maternal pre-pregnancy obesity is associated with autism-like behaviors in offspring."

Caveats? Well, yes, a few. Height measured in the second trimester but participants "reported their pre-pregnancy weight"? I can see a few complications there in terms of accuracy of recall and perhaps the possibility of some bias creeping in. Having said that, many mums-to-be do have records of their weight during that 'special time' and some probably before as part of their regular clinical care or just as a result of how health conscious everyone is being these days. That and the fact that most people roughly know their typical weight (outside of pregnancy).

But also the AQ... the AQ. Regular readers probably already know that I have some qualms about the AQ and it's 'specificity' when it comes to autism and autistic traits (see here and see here). I know it's often seen as one of the internet's premier 'are you autistic?' instruments, but sometimes I think it's done more harm than good by way of it's probable link to the rise and rise of the 'self diagnosis' (see here) for example. I could go on about this, but I won't. Instead I'll just mention that 'autism-like' behaviours as judged by the AQ is probably the correct phrase to use in the context of the Varcin paper. Indeed, one might easily suggest that in a non-clinical population, AQ might also be tapping into other labels and traits [2]: "Higher AQ scores were associated with higher scores of loneliness, social anxiety, depression, and anxiety, as well as with lower scores of quality of life (QoL)." So unless one accepts that depression and/or anxiety might potentially be core features of autism (see here and see here), AQ might be picking up other things other than autism.

Still, I can't argue with the *association* talked about by Varcin et al, and what it might mean for the quite spectacular rise and rise in the numbers of people being diagnosed with an autism spectrum disorder (see here). No, not by any means the only factor to account for the increase in diagnoses, but potentially an important part of the story...


[1] Varcin KJ. et al. Maternal pre-pregnancy weight and autistic-like traits among offspring in the general population. Autism Res. 2018 Sep 19.

[2] Reed P. et al. Loneliness and Social Anxiety Mediate the Relationship between Autism Quotient and Quality of Life in University Students. Journal of Developmental and Physical Disabilities. 2016; 28: 723-733.


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