Ms. Muddle -- do you mean generally? 

I presume you're asking in the context of ADD and ADHD?

Do one of you have it or, do you have a child with it?

My experience is more direct with a child, and there is no doubt it offers additional tension.  So much of the logistics (doctors, checking in on homework, teachers) etc. must be shared, but in the end in my case my poor wife is on the front line more regularly due to my work.  We agree mostly on the larger issues and commitment, but don't always hear each other in the detail.

So I've found that having great respect for our commitment to our son, knowing we both come from the best place for him, my appreciation that she carries more daily burdens and just checking in:  "am I hearing this correctly?" has helped some.

And I suspect this holds generally.  A dear friend has ADD and in her marriage she is left with all the family logistics.  So imagine that -- the very way her wonderful and creative mind works is NOT ideal for logisitics and execution! 

Diagnosis was the first step for both of them, and has put them on a very different and positive path.

Not sure if this helps.  Best, CMSchroed