Oppositional Defiant Disorder Information?

I've read around this disorder and I've seen a lot that indicates only children get this kind of disorder, and that it's usually linked to ADHD. But can adults have it? And by this I mean ODD and not ADD, as ADD is like ADHD but ODD involves being hostile, irritable and uncooperative, being spiteful or annoying on purpose, and directing negative emotions at authority figures.

If you want to know why I'm asking about this, firstly It's just because I'm interested, but secondly it's because I'm writing a bad story and I noticed, after having a conversation with a psychology student and Googling behavioural disorders, that the description of ODD very much fitted the way I'd written one of my characters. I could include it in my story to give her more substance, but as I mentioned at the beginning it's usually only seen in children, and the character is 24 years old. If it isn't possible I'll leave it out, but I'm all for including real-world issues in my story, and I just wanted to see if anyone knew.

Thanks in advance for any answers