Well, I am by no means a psychiatrist or any specialist in the field of the workings of the mind - I don't really know what I'm talking about or how accurate anything is that I'm thinking!
However, given the responses here, I would say that a higher majority do experience the three conditions I spoke about; at least, more do than don't. Would you all agree?
I was pondering this last night as I wrote this out - but it's very important for me to be somewhat in the mindest of wanting to prove or disprove my thoughts - because it's easy to fool yourself when you're thinking about these things, ya know?
My thoughts are that humans are environmentally defined by the input of their senses and of the thoughts that occur surrounding those senses. I say "environmentally" (which is probably a poor use of the word) because we define (or more accurately center - yes, I like the word "center" more) ourselves, I believe, closely with our environment - we have two sides, fundamentally, I guess, the outside and the inside - and the inside takes queue of its processing (sensory or otherwise) from the outside. So, humans define themselves as much with their environment as with their insides - which is why "home feels good"; I guess. Imagine uprooting a human to a totally foreign environment - their anxieties are likely to be higher; especially if they are prone to such things.
It's my guess that those who suffer from ADHD - as I do - are less likely to form deeply rooted ties to their environment, or at least as deep as those who do not. The inability to focus also means the inability to draw deep associations with your environment; you don't live as much in the environment as others do because your mind is, I can only assume, flittering about in other worlds too. A classroom, to some, is the same classroom as the day before - but someone with ADHD, or some other form of attention problems - doesn't live in the classroom inasmuch as they do their mind, and so the ability for the classroom to take on a different environmental tone is high. It's fuzzily stated - but can you see what I'm getting at?
Attach to this an anxiety issue, where someone is highly prone to be anxious, and you might have the makings of someone who has a hard time coping with environmental changes or stressors and feeling "grounded" or "together" with their world and themselves. Someone who never had the abilities to ground themselves mentally due to their fast-moving, highly-sensory-triggered mind won't have the long-term, consistent view on the world to secure them in the event of stresses or significant life changes. Morals, opinions, choices, mindsets will be more likely to change and a person might feel themselves more "awash" with the world about them.
The anxiety serves as a magnifying glass - where you can hyper-focus on particular issues that stress you out (and someone in this situation might become highly stressed about their environment and their place in it). Suddenly - boom - someone hyper focuses on existential (sp?) things that relate to their anxieties - become more anxious because they do not have the steady foothold on their surroundings as they, otherwise, would have had they not had attention problems. The wild imaginations and, typically, intelligent minds continue to push the feeling.
So, lack of attention results in lack of real-world foothold and consistent intra-/extra-personal attachment. Highly sensitive means quickly and easily picks up inconsistencies, world changes, and stressors (also typically means highly intelligent - which is more prone to thinking). Anxiety pushes magnifying glass on the problem, decenters us because of the panic "fight or flight" condition, and you're off - totally depersonalized, uncentered and the world is unreal.
This was a complete brain dump - and these thoughts are still jumbling about, making weird connections and stuff. I hope we can mature them together, I guess.....
