I believe that ADHD can be exacerbated by specific events and general life stages. I used to think that it was a coincidence that my husband's problems seemed to get worse when my daughters became preteens and that his problems have continued to be worse as they have grown into young adulthood. Now I'm starting to think that this is one of those life stages that, by challenging his parenting abilities, has worsened his ADHD and related conditions. It seems that my husband is not very aware of appropriate behavior for the parent of a young adult and so the stress of figuring out what is appropriate might be making his ADHD harder to deal with.
Here is an example (which might have nothing to do with ADHD): My husband likes a TV show that features 20-something young women. They are shown having sex. My husband introduced this show to my daughters, ages 19 and 21. He really wanted me to watch it. He put it on and there we all were, watching a show in which women the age of my daughters were having sex; my daughters know this is their father's favorite show. I felt creeped out. Good show, yes; watching it with my husband AND daughters made me feel yucky.