Speaking from personal experience of having post natal depression after the birth of both of my sons, I find the above statement partially true.
I found the anti depressant Seroxat to be fantastic. I was singing all day long and nothing could get me down. I felt the happiest I had ever felt. It was amazing for me. However, after reasearching it thoroughly, I was not happy about the withdrawal symptoms that so many people had suffered after having taken it for long periods of time, so I swapped about onto different ones....and not one of them worked!
Eventually, I just stopped taking anything and waited (in misery, whilst trying other self-help remedies) for it to pass...which it eventually did.
So it really depends on the body chemistry of one individual being responsive to the chemical arrangement of a particular anti depressant.