Hello Haydee,
Basically an hormonal imbalance due to prolonged exposure to excessive levels of the Cortisol Hormone causes Cushing's Syndrome.
It is a relatively rare condition and usually affects people between 20 & 50 years of age.
There is a lot of information on the Internet about the condition and a quick Search Engine search will bring up 200.000+ pages on the subject. Simply type in 'Cushings'.
I have given you a couple of links below which I think may be worth a visit.
http://cushings.homestead.com/
http://www.cushings-help.com/intro.htm
I hope this has been of some help to you.
Poseidon