I'm an 18 year G.A.D patient due to Vestibular and Optic sensory processing disorders. I'm an 18 year user of Xanax. My wife is a 28 year user of Xanax for Anxiety. An antidepressant for someone with this type of General Anxiety Disorder can have bad results. I've seen the worse an antidepressant can do to someone short of death. It happened to my wife when a doctor tried her on antidepressants.
My medical records and hers have Allergic to Antidepressants in them. Ironically Benzodiazapenes is the protocol antidote to stop an adverse reaction antidepressants can cause called Serotonin Syndrome.
You should read the U S Army Medical Command memo of
April, 2012 which details how benzos are contra indicated for soldiers with PTSD as they exacerbate the trauma, not cure it.
My personal experience has been that the vestibular and occular processing problems are often psychologically based.