Monday, 15 February 2016

A familiar message... maternal immune disease and offspring ADHD risk

"Several maternal somatic diseases with immune components were found to increase the risk of ADHD [attention-deficit hyperactivity disorder] in offspring."

That was the research bottom line reported by Johanne Instanes and colleagues [1] following their analysis of some 48,000 people with ADHD (well, "receiving ADHD medication during the years 2004-2012") compared against over 2.2 million control individuals (er, not receiving ADHD medication). Indeed, once again those very useful Scandinavian registries (see here for example) keep on giving in research terms, this time based on "data from longitudinal Norwegian registers."

The sorts of diagnosis included under the heading of "chronic somatic diseases with immune components" that were found to be related to offspring ADHD ranged from multiple sclerosis to type 1 diabetes. Even taking into account potentially important variables such as parental ADHD and gestational age did little to alter the odds ratios reported; although analyses by gender did seem to produce some potentially interesting results when it came to maternal asthma for example, and boy vs. girl offspring risk of ADHD. The authors conclude that: "insight into the mechanisms behind these relationships could enhance our understanding of the etiology of ADHD."

I titled this post 'a familiar message' because the data reported by Instanes et al seems to follow a trend of large population-based inquiry reporting offspring developmental outcomes when certain maternal immune-related diagnoses/pathology are present. Y'know things like a potentially slightly increased risk of offspring autism in the presence of maternal thyroid autoantibodies (see here) or how the appearance of psoriasis in one or other parents might also play a role (see here). Yes, correlation is not the same as causation but let's face it, the involvement of the immune system in at least some cases of autism is hardly a new thing (see here for example). Indeed, let us not forget 'MAR autism' (see here) (as many people seem to have).

That ADHD is also one of the most common overlapping diagnoses associated with autism (see here) further extends the idea that maternal immune related features (potentially present during some critical period during pregnancy/gestation) might extend to a number of diagnoses. Nature also tends to blur diagnostic boundaries (see here).

What's more to say? Well, having specifically mentioned asthma already, I was quite interested in the data suggesting that maternal asthma might be something to look further at with offspring outcomes in mind on the back of other data (see here). More and more science is also realising that asthma and ADHD are not uncommon bedfellows (see here and see here) and given the suggestion of heredity strongly governing the onset of asthma (see here) one can perhaps see how this data might strengthen the possibility of a wider association. Remember, genes suggested to play a role in specific conditions are generally not confined to one diagnosis (see here) as we've seen in recent times [2]. Dare I also mention how the use of certain medicines during pregnancy might also have a bearing on both the presentation of asthma [3] (see here also) and perhaps even more behavioural indicators (see here) too?

Further research is of course indicated.

Music: Viola Beach - Swings and Waterslides. RIP.

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[1] Instanes JT. et al. Attention-Deficit/Hyperactivity Disorder in Offspring of Mothers With Inflammatory and Immune System Diseases. Biol Psychiatry. 2015 Dec 9. pii: S0006-3223(15)01034-3.

[2] Hagenaars SP. et al. Shared genetic aetiology between cognitive functions and physical and mental health in UK Biobank (N=112 151) and 24 GWAS consortia. Mol Psychiatry. 2016 Jan 26.

[3] Magnus MC. et al. Prenatal and infant paracetamol exposure and development of asthma: the Norwegian Mother and Child Cohort Study. Int J Epidemiol. 2016 Feb 9. pii: dyv366.

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ResearchBlogging.org Instanes JT, Halmøy A, Engeland A, Haavik J, Furu K, & Klungsøyr K (2015). Attention-Deficit/Hyperactivity Disorder in Offspring of Mothers With Inflammatory and Immune System Diseases. Biological psychiatry PMID: 26809250