Friday, 9 January 2015

Early mortality in mums of children with autism or intellectual disability

I know the paper by Jenny Fairthorne and colleagues [1] (open-access) is probably not the happiest thing to read with their conclusion that: "During the study period, mothers of children with intellectual disability or ASD [autism spectrum disorder] had more than twice the risk of death" but their message is nonetheless an important one.

Based on data derived from "state-wide databases" covering women living in Western Australia who gave birth between 1983 and 2005, researchers detected mums with a child diagnosed with autism and/or intellectual disability (learning disability if you prefer) and cross-referenced findings with "the state mortality registry" providing information on "dates and cause of death by ICD-9 or 10 codes". Various study (case) groups were formed on the basis of offspring diagnosis - intellectual disability (ID) of unknown cause (further separated based on levels of ID), ID of known cause (specifically Down syndrome or other) and a diagnosis of autism spectrum disorder (ASD) with and without ID - and aided analyses.

After some correction for various confounders including maternal age and socio-economic status (SES), from a starting population of some 300,000 mothers, approximately 1% had died before 2011 (the longer follow-up period). To quote: "Twenty-five years after the birth of their index child, the survival rates of mothers of children with no intellectual disability and no ASD were about 98%, followed by 96% for mothers of children with ASD and 95% for mothers of children with intellectual disability." These group difference were significant and led researchers to draw the conclusion: "Mothers from all case groups had an increased risk of death during the study period."

A few other details are also recorded in the Fairthorne study. "Mothers with both a psychiatric disorder and a child with intellectual disability or ASD had about six and a half times the risk of death" was an important finding reported by the authors. When it came to the cause of death, various factors were over-reported in case group mums including cancers, cardiovascular disease and death by misadventure (death due to an unintentional accident, homicide or suicide according to the authors' criteria).

Reiterating that the Fairthorne paper makes for quite uncomfortable reading, there are some potentially important lessons to be learned from the collected data. First and foremost I should stress that the excess percentages of deaths reported during the study period were overall, quite small for the case groups. Whilst there was an excess of deaths over and above that seen in the asymptomatic control group, the data do not suggest that mothers of children with autism or Down syndrome for example, are facing a gigantic excess risk. Risk is risk and influenced by lots of different variables. I say all that with my cold, dispassionate science goggles on, recognising that each death is a mother lost.

That being said, one might make a case for further inspection of maternal (and paternal) health and wellbeing as and when a diagnosis of autism and/or ID is received in one or more offspring. I've covered the topic of parental stress and autism before on this blog (see here) and the [evidence-based] ways and means it might be reduced. Stress is mentioned in the Fairthorne paper as potentially being one factor linking parenting and early mortality although I'd also suggest the concepts of resilience and coping might also require investigation.

Maternal health issues such as a history of psychiatric issues and/or more somatic diagnoses like diabetes and obesity are also covered in the discussion on possible reasons for the added risk in case groups. As per the research suggesting that some of these factors alone or in combination might increase the risk of offspring autism for example (see here), management of said issues should also rank high on the list of monitoring parental wellbeing. Lifestyle issues such as tobacco smoking and poor exercise regimes can also be mitigated if and when required.

Finally, I want to make one further point specifically related to the idea that cancer may feature as one reason for the excess mortality noted in the current study. Late last year (2014) I covered the complicated issue of cancer risk and autism (see here) on the basis of some further 'big data' derived from the Taiwan National Health Insurance database [2]. In amongst the discussions on that post was some mention of a familial history of certain cancers potentially being heightened in cases of autism on the basis of data from Ingudomnukul and colleagues [3]. The Fairthorne data corroborates this view, and further implies screening should perhaps be preferentially extended to mums of children with ID and/or autism. Early detection can save lives.

Mortality and autism is never going to be a great topic to discuss whether based on personal experience or the peer-reviewed evidence base. Linked to the suggestion that a diagnosis of autism - or at least some of the comorbidities which it can carry - for example, might also elevate the risk of early mortality (see here), I believe that it is time to start bigger conversations on how science and society can go about reducing such risk and reducing health inequality. Mothers, like their children, are precious things...

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[1] Fairthorne J. et al. Early Mortality and Primary Causes of Death in Mothers of Children with Intellectual Disability or Autism Spectrum Disorder: A Retrospective Cohort Study. PLoS ONE. 2014; 9(12): e113430.

[2] Chiang H-L. et al. Risk of Cancer in Children, Adolescents, and Young Adults with Autistic Disorder. J Pediatrics. 2014. 18 November.

[3] Ingudomnukul E. et al. Elevated rates of testosterone-related disorders in women with autism spectrum conditions. Horm Behav. 2007 May;51(5):597-604.

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ResearchBlogging.org Fairthorne J, Hammond G, Bourke J, Jacoby P, & Leonard H (2014). Early Mortality and Primary Causes of Death in Mothers of Children with Intellectual Disability or Autism Spectrum Disorder: A Retrospective Cohort Study. PloS one, 9 (12) PMID: 25535971