As a man who suffers manic depression, I would tell the gentleman you know that he needs to see a doctor and start seeing a therapist. That if he gets medicine and appointments with a therapist that takes away his depression, his pain, then that is a wonderful thing.
I look at psychiatric medicine as a form of pain killers, since any type of mental illness such as paranoia, hallucinations, thought disorder, delusions, mania, or depression is the source of tormenting pain at times. I should know I suffer from all of the above without medicine.
If that man you know had a shooting pain is his left arm he would gladly see a doctor and take medicine to relieve the pain, I hope. The same is true of psychiatric medicines. Now, the problem may be he might have to try out a number of medicines before he finds the right one with a minimum of side effects and maximum of results, I know I had to. That said, he absolutely needs a doctor and therapist if he has depression. I don't know where I would be if my depression was not treated by a doctor, medicine, and therapist.