My cousin suffered from depression for 10 years +.
His wife worked, but eventually that was not enough
with rise in cost of living, etc. He had to find
an attorney in Chicago area who specialized in special
disability cases. SS had always turned him down as
he was in his 50's (but had worked 30 yrs.!)
This attorney was able to get his Social Security
benefits for him by claiming a mental disability.
It takes persistence.
i was diagnosed bi-polar almost 9 years ago and was granted disability a couple years later. unfortunately for your case, i had other health problems to add in to the mix. but again, persistance is the key. if applying on your own doesn't work, hire a lawyer. the lawyer won't require payment unless social security finds you disabled. good luck!
My dad was diagnosed with bipolar disorder about a year ago, doctors took him out of work, and he is just now recieving his social security..but good lord, he had to go through a lot to get it. :\ Several doctors/lawyers...and of course the company wasn't happy with him. They battled until the end. But my dad came out on top and I'm happy for him!
BI-POLAR 
