I have a friend suffering from depression. He takes anti-depressants to help.
People woth depression may be notably sad, anxious, or empty; they may also feel notably hopeless, helpless, dejected, or worthless.
Yeah I feel sorry for them. It must be tough to feel those emotions.
It is a very difficult thing that can affect a person's thoughts, behavior, feelings, and sense of well-being.
I am glad that there are drugs that also help such as Prozac and Paxil.
Sometimes depression is a normal temporary reaction to life events and drugs are not needed. 
That is true. Sometimes psychotherapy is all that is needed for patients to start feeling better.
Psychotherapy is aimed to improve an individual's well-being and mental health
Yeah I believe Sigmund Freud started the practice. It has helped so many people!
Yes and Freud also qualified as a doctor of medicine.