What is it called when you always think of the worst for yourself you think your gonna die and you think you have diseases

What is it called when you always think of the worst for yourself…?

http://www.chacha.com/question/what-is-it-called-when-you-always-think-of-the-worst-for-yourself-you-think-your-gonna-die-and-you-think-you-have-diseases

A hypochondriac (n) is a person who has a preoccupation with minor abnormalities viewing them as major medical issues.