Why does the drug speed age you so swift?

I've seen pictures of young at heart twenty year olds and a picture of them having used speed for two years and they look 50 years prehistoric. What in it make it age them so fast?Why does the drug speed age you so swift?
scarcity of hygiene. when you get soaring you twitch and stuff and you scratch your obverse because you start to develop bumps. you lose your teeth, too. but of course this is adjectives opinion, dammit.
they don't. 20 years hoary after 2 years, with or near out the drug would be 22 years old.
Chalk it up as only just something to muse over and something that we'll never really understand helpful of, like "why is rush hour other the slowest hour of the day."