I think it is possible. I have been struggling with a similar problem the past few months, after giving myself what might be called a "chemical PTSD" by taking something that sent my anxiety through the roof.
Chemically, I think it has something to do with dopamine and norepinephrine. Dopamine is a "feel good" chemical, but it gets converted to the excitation chemicals norepinephrine and epinephrine (adrenaline), and I believe it does so at a higher rate in those with PTSD or other anxiety provoking experiences. This may be due to something called "dopamine beta hydroxylase," which converts dopamine to norepinephrine. Supposedly one can reduce the effects of this by eating celery seed, though I haven't tried it.
One thing that has helped me (though I strongly urge everyone to be SUPER SUPER CAREFUL about supplements, having had a few very bad experiences), and which apparently has helped other PTSD sufferers is an amino acid found in tea, called l-theanine. It is available in 100 mg caps and provides a very mild calming effect that also seems to help with the dysphoria of anxiety. Some people say it helps their anhedonia in stronger doses.
I have also had some success with supplements aimed at increasing acetylcholine, which is sort of an opposite kind of stimulation relative to dopamine, such as manganese and DMAE. But again, I'd only proceed with great caution.
The best cure, I think, for chronically elevated stress and anxiety, is regular meditation, lots of exercise, cutting down stress as much as possible, and time, time, time. I have sometimes made myself worse in a rush to get better, underestimating the healing power of time.