Several cups of coffee per dayor 400 mg of caffeine reduces suicide risk by 50 percent

Oh yeah? on what authority? I would love to know how they can make such a study since I believe suicide is not usually that pre-meditated.

Several cups of coffee per dayor 400 mg of caffeine reduces suicide risk by 50 percent
http://nextbigfuture.com/2013/08/several-cups-of-coffee-per-dayor-400-mg.html