It's been quite a few years since I've approached the topic of parental separation/divorce in the context of an offspring diagnosis of autism or attention-deficit hyperactivity disorder (ADHD) (see here). The net result of that discussion was that the (peer-reviewed) evidence base, at the time, was a little mixed when it came to whether parental separation was more or less likely in the context of offspring autism for example. Indeed, whilst family parenting pressures no doubt contribute to parental relationship 'anxiety', there are a myriad of other factors to take into consideration too...
Fast forward to recent times and the study results published by Sabrina Just Kousgaard and colleagues  make for the blogging fodder, with their conclusion that: "Parents of children diagnosed with ADHD or ASD [autism spectrum disorder] were more likely to separate than control parents."
From a cold, objective science view the Kousgaard study is a well-powered one, insofar as including "the parents of 12,916 children with ADHD, 7496 children with ASD and 18,423 controls." With those sorts of participant numbers, you probably won't be surprised to hear that the source country was Denmark and yet again, the use of one of those fabulous Scandinavian population registries. Indeed: "all children with ADHD or ASD born between 1990 and 1998 in Denmark" were studied and followed-up "until the child's 25th birthday, parental separation or December 31, 2015, whichever came first."
Authors acknowledge that although there was a higher rate of parental separation in those families with a child with autism or ADHD it wasn't as straight-forward as 'blaming' offspring diagnostic status or not. So: "Other factors associated with parental separation were parental imprisonment, parental psychopathology, low parental education level, low household income and living in a larger city." What this finding does is reiterate that family circumstances are universally 'weird and wonderful' and that just because there is a child or children in the family diagnosed with autism or ADHD (or both) does not mean that families are any more or less 'weird and wonderful'.
Then to the big questions: (i) why was the parental separation rate elevated when autism or ADHD is diagnosed in the family, and (ii) what can be done to help families 'stay together'? Well, without getting too high-and-mighty about this (acknowledging for example, that in some circumstances parental separation is actually a better option than a continued 'toxic' family environment) there are other clues in the research literature (see here).
So, first of all let's acknowledge that parenting is tough. That's a universal issue, irrespective of whether children are diagnosed with this, that or t'other. Having a child with a developmental disorder/label/diagnosis does seem to make things tougher insofar as the additional 'things' that need to be catered for, and the almost constant battles that follow trying to get those additional 'things' catered for. I say this not only from the perspective of the parent-child relationship but also the additional strains related to schooling and education and navigating often complicated social welfare systems for example. It's little wonder that some parents voice sentiments like 'why I can never die' in this context (see here). The research literature is also pretty much unanimous that quality of life for parents with a child with a developmental diagnosis is reduced compared with families without that diagnosis (see here). This also highlights how such pressures take their toll both psychologically and physically. There is no malice intended in that last sentence and no blame to be apportioned; I'm just guided by what the research in this area is telling us.
From the perspective of parents and their relationship with each other, it's not difficult to see how diverting energy into a family and their welfare often means diverting energy away from each other. The words 'emotional roller-coaster' have probably been used more than once to describe parenting a child with a behavioural and/or developmental diagnosis, and minus any psychobabble, such a roller-coaster can be emotionally draining. Yes, there are ups, but also there are downs; and in the context that various types of 'energy' (psychological and physical) are often finite in amount, so when such energies and time are focused on a child or children, there is logically, less for the other significant partner. Simple physics. Throw in the dwindling resources devoted to something like respite care for example (see here) and, well, you can see how this might quite severely affect the family dynamic. And results also tend to be cumulative...
I don't doubt that the issue of parental separation in the context of an offspring developmental and/or behavioural diagnosis is a complicated one. People split up all the time and, more often that not, it's more about the people (parents) themselves and their relationship than anything else. It would be foolish however to disregard data such as that generated by Kousgaard and colleagues showing how context and environment can also play a (variable) role when it comes to family break-up.
And on the back of the Kousgaard results, it's perhaps also time to start thinking about how parental break-up / separation might affect said offspring, particularly when a diagnosis of autism and/or ADHD is part of the clinical picture...
 Kousgaard SJ. et al. The effect of having a child with ADHD or ASD on family separation. Soc Psychiatry Psychiatr Epidemiol. 2018 Aug 28.