Being an addiction psychiatrist, I see a lot of people who come to me for opioid dependence who are also using high doses of benzodiazepines. With buprenorphine, their anxiety generally improves a little but they are frightened by the idea of living without benzodiazepines. Nonetheless, a condition of treatment is tapering off. What I have found repeatedly is that as they decrease the dose and finally get off, their anxiety improves dramatically. I wonder if there is a benzodiazepine-induced hyperanxiety syndrome akin to opioid-induced hyperalgesia.
This is an interesting observation and a good hypothesis. PL has little experience to add but would like to bring this observation to the attention of readers. It makes sense that the brain may adapt to benzodiazepine use in some patients such that the homeostatic mechanisms involved produce more clinical anxiety. In other words, if gabaergic activity is increased with a medication, then the brain’s homeostatic mechanism could be to increase compensatory glutamatergic excitation, which can produce anxiety. Once the exogenous gabaergic stimulation is reduced (i.e., benzodiazepines are stopped), the homeostatic reaction may also decline (i.e., glutamatergic excitation will diminish), producing less clinical anxiety. This is a biological hypothesis to explain your clinical observation, but the important matter is that the clinical observation you describe makes biological sense. It should be kept in mind with some patients in whom long-term benzodiazepine use may be part of the problem, rather than the solution, in managing refractory anxiety.