There are a lot tapes, machines, programs and the like to cure or at least control depression. Each vendor will assure you that their program is the one that will work. Added to this, there are a number of things that could contribute to your friends bouts of depression. NBG is a good start, there is New History Generator as well as the Euphoria! p.r. program.
Your friend's depression may need the help of another counselor or practioner, has he considered a second opinion? I could tell you about my own personal preferences, but your friend's needs seem more immediate.
Good Luck! 
