It is possible that tremendous amounts of stress could contribute a little bit to hair turning white (in a person who is at least over 35), but not a significant amount.
Too much stress just isn't healthy- that's all you really need to keep in mind.
Besides, I'm usually really stressed and angry and unhappy and frowning all the time, but my hair is still perfectly red. haha
Attention: NOTHING on this site may be reproduced in any fashion whatsoever without explicit consent (in writing) of the owner of said material, unless otherwise stated on the page where the content originated. Search engines are free to index and cache our content. Users who post their account names or personal information in their questions have no expectation of privacy beyond that point for anything they disclose. Questions are otherwise considered anonymous to the general public.