Treatment resistant depression is depression that has failed multiple treatments including ect, medications, and other standard therapies. Have litterally been on all the drugs available except for MOAIs have had 18 ect treatments, been in the hosp multiple times, been to multiple pdocs and therapists. That is as good as a definiation as I know, and yes I have been faithful in my drug regiemes, my followup appointments, therapy sessions etc. It is the diagnosis currently on my file at each of the above docs, therapists and hosp. Been treated unsuccesfully for many many years, seem to get no better but do have many days when it is worse.