i am 24 and am suffering from the same thing. i didnt know if it was high blood pressure or stress that was causing it, but i ended up in hospital recently after smoking a cigarette, ive been smoking for about ten years. ive noticed in the last 2 years or so this has appeared more often. i also smoke a fair bit of weed too. my hands in particular go quite whitish/blueish with every vein underneath very visible and large. I did ask the hospital if this was normal, i the doctor said it was. I dont believe a word of it, my hands look like those of a seventy year old...