I don't really have an opinion, just a little thinking-out-loud on these issues (uh oh). I have read that people with ADHD tend to be (though not always) right-brained, visual-spatial learners. (mostly in Silverman's book; see also
http://www.visualspatial.org/Articles/george.pdf ) And I do feel like I keep seeing other issues - sensory and motor in particular (though ocular motor is really a subset of sensory processing disorder) - in right-brained, VS learners like two of my kids. I think it may merely be that the sensory/motor stuff represents different sorts of left-brain weaknesses. As for the ocular motor, somewhere in the course of vision therapy I think I read about cases that were misdiagnosed as ADHD - but misdiagnosis is a very different issue from the issue of whether adhd and ocular motor issues are linked.
I wish I had input on OCD tendencies - my dd tends to have both a defiant and obsessive need to speak a certain way to me (essentially backtalk that I "cannot allow"; what does that even mean). It was part of the reason we did OT for SPD. Thankfully it's improving with age, though when she's tired, etc. it rears it's ugly head. But it never rose to the level of ODD with other adults, so I don't know anything about that - it's been too long since I read about the topic.
I am not familiar with ADHD as being a "spectrum" disorder and frankly without more I think that carries the spectrum (as vague as it is) much too far. AHDH has its own specified DSM criteria to begin with, and I thought the "spectrum" was PDD-NOS, as in "not otherwise specified", such that by definition it could not include ADHD. Meanwhile, I don't necessarily see any link between autism proper and ADHD except that again they may both tend to be right-brained thinkers.
I thought ADHD isn't usually diagnosed until around 7 y.o.?
I guess my bottom line opinion is that plenty of these issues (sensory, motor, adhd, odd) exist on their own, and the fact that some people tend to have a group of them does not mean they are necessarily linked. My guess is just that the issues are different kinds of left-brain weaknesses in right-brained thinkers. I think the spectrum stuff is a separate animal as well, since plenty of people have sensory issues, for example, without being on the spectrum. I hate that there even is a spectrum because I think it is so ill-defined, which ultimately leads to more difficulty in communicating about a particular child's situation rather than less difficulty (too many different pre-conceived notions of what it means). With that kind of vagueness almost any issue could be called a spectrum disorder, even though it may have no relation to actual autism whatsoever. At least with autism the DSM criteria are more specific, involving severe lack of empathy.
It was probably a bad idea to think out loud on this board on not enough sleep. But that's my two cents - I can't comment on the ODD, but as far as the ADHD goes I'd need to have someone spell out for me why they think it should be considered a spectrum disorder because it doesn't make sense to me. It sounds like the guy who wrote the article thinks that all such people, who are right-brained thinkers with any left-brain weaknesses (ok, that probably would include me LOL), are on the spectrum, and that pathologizes far too much of what I believe are normal ways of thinking.
ok I better stop now before I say something even more dumb...