i respond very well to stimulants also
i was diagnosed with ADD/ADHD, and i found my anxiety was much less when i took stimulant medication
from what i gather, ADD/ADHD symptoms are caused by lack of stimulus in the brain. the brain is constantly trying to find things that it finds stimulating, hence the distractability, inattention, etc. if something you're supposed to paying attention to is boring, the brain finds it hard to focus, and if it finds something particularly interesting, it has a hard time switching away to something else.
negative emotions - worry, fear, anxiety, depression - can all be very stimulating, so the ADD/ADHD brain likes to focus on these things in the absence of other more positive stimuli
stimulant medication, like ritalin or adderall - or caffiene - stimulate the brain so that it actually calms down and stops scanning for stimulus and you can focus. and it also allows you to stay fixed in the present and not preoccupy your mind with the stimulating negative emotions
just a theory as to why it works for me - can't say for sure if that has anything to do with what you're experiencing