They really don't know what causes anxiety, or clinical depression. The are having a horrid time finding the true cause of these ailments. If anyone is seeing a MD who claims to know what causes depression and anxiety see someone else. It gotten so disappointing in the research community; very few companies are actively even looking for the root cause to these horrid diseases. So many people took these tri, and hetrocyclic drugs for depression, and if they worked--it was most likely placebo. Yes--panic attacks, and generalized anxiety respond to benzodiazepines most of the time, but hey are addictive, and no researcher who is smart would Not claim to know how they work. I wish you well.
I truly believe the best medicine is knowing you are going to get better. The placebo effect is sometimes stronger than any antibiotic. I sometimes believe the placebo effect is the only verifiable existence of God? When I am sick, I do a little research on the Internet, but have found it's better to just believe the medicine will work. Oh yea, I try to chose my doctors well--Board Certified who actually tried to keep current after years of practice.