Tuesday, 14 June 2016

On fatty acid metabolism and autism and ADHD (again)

"Children with ADHD [attention-deficit hyperactivity disorder] and ASD [autism spectrum disorder] had low levels of EPA [eicosapentaenoic acid], DHA [docosahexaenoic acid] and AA [arachidonic acid] and high ratio of n-6/n-3 PUFAs [polyunsaturated fatty acid] and these correlated significantly with symptoms. Future research should further investigate abnormal fatty acid metabolism in these disorders."

So said the research publication by Natalie Parletta and colleagues [1] (open-access available here) who completed assessments on erythrocytes in blood samples from "565 children aged 3-17 years with ADHD (n = 401), ASD (n = 85) or controls (n = 79)." Alongside fatty acid analyses (undertaken at "a commercial Pathology Laboratory") researchers also included various behavioural measures with their participant group looking at aspects such as attention and impulsivity and also autistic symptoms (via the CARS). Importantly we are told that: "Participants who had taken any nutritional supplement during the previous year were excluded" from the study.

Results:  well as I've mentioned, compared to the asymptomatic (not autism nor ADHD) controls, group values for those with autism or ADHD were lower in terms of EPA and DHA among other things. In fact we are told that: "Children with ASD had lower DHA, EPA and AA and higher n-3/n-6 ratio than children with ADHD" suggesting that fatty acid metabolism might be even more irregular in this group compared to the others. EPA and DHA specifically fall under the banner of omega-3 fatty acids and are generally thought to be the 'good guys' when it comes to all-manner of health effects. I might particularly mention the word 'inflammation' when it comes to this class of fatty acids [2] which could be relevant to quite a bit of the autism spectrum as well (see here). When it however came to the overall ratio between omega 3 and omega 6 fatty acids (sometimes thought of the not-so-good guys), it was ADHD that beat autism that beat controls. The authors make a case for some interesting correlations between fatty acids levels and the various behavioural scores obtained but to be honest, I'm not all that impressed with the figures as they stand.

I've used the word 'again' in the title of this post to denote how this is not the first time that unusual fatty acid metabolism has been described with both autism and ADHD in mind (see here and see here respectively). Minus any sweeping generalisations, the body of peer-reviewed evidence looking at fatty acids and autism or ADHD is pretty consistent in the the findings being reported that one for reason or another, there seems to be 'issues' with fatty acids and screening services should perhaps be preferentially offered as and when a diagnosis (or both) is received."This cross-sectional study is the largest of its kind, supporting previous work that showed low n-3 PUFA levels, particularly DHA, in children with neurodevelopmental disorders." Indeed.

Then comes the question of whether supplementation as and when an atypical fatty acid profile is detected might be useful or not. The jury is still out on this side of things particularly when it comes to autism and the possible effects of supplementation (see here). For ADHD the evidence is a little stronger (see here) and continues to garner research attention [3] as a potentially cost-effective intervention option for some. I was also intrigued to read the authors' reasoning on a possible role for the trillions of wee beasties that call us home (the gut microbiota) and how: "Another explanation could involve the influence of gut microbiota on PUFA uptake and metabolism." In an unrelated post, I've talked about research suggesting a possible role for fatty acids in terms of gut bacteria and something like obesity (see here). One therefore wonders how deep the rabbit hole might go?

For now however, we have more scientific evidence for a potential role for fatty acid metabolism and at least some autism and ADHD...

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[1] Parletta N. et al. Omega-3 and Omega-6 Polyunsaturated Fatty Acid Levels and Correlations with Symptoms in Children with Attention Deficit Hyperactivity Disorder, Autistic Spectrum Disorder and Typically Developing Controls. PLoS One. 2016 May 27;11(5):e0156432.

[2] Simopoulos AP. Omega-3 fatty acids in inflammation and autoimmune diseases. J Am Coll Nutr. 2002 Dec;21(6):495-505.

[3] Gow RV. et al. Current evidence and future directions for research with omega-3 fatty acids and attention deficit hyperactivity disorder. Curr Opin Clin Nutr Metab Care. 2015 Mar;18(2):133-8.

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ResearchBlogging.org Parletta N, Niyonsenga T, & Duff J (2016). Omega-3 and Omega-6 Polyunsaturated Fatty Acid Levels and Correlations with Symptoms in Children with Attention Deficit Hyperactivity Disorder, Autistic Spectrum Disorder and Typically Developing Controls. PloS one, 11 (5) PMID: 27232999