Caffeine addiction, a serious problem according to the USA
Published on 3/2/2014
Coffee regulars number in the millions; those truly capable of giving it up are very few. The reason would lie in caffeine addiction, which several scientific studies take as established. Removing the "coffee ritual" from a large part of its consumers, then, could trigger symptoms comparable to a withdrawal crisis.
The most recent studies seem to converge on a limit to caffeine consumption equal to 400mg/day, beyond which one runs the risk of developing negative symptoms. For subjects such as pregnant women, hypertensives, and people suffering from insomnia and anxiety, the maximum recommended consumption should not even exceed 200mg/day.
A study conducted in the psychological field by Dr. Juliano together with several university institutions—from American University to the Johns Hopkins School of Medicine to the University of Vermont—and published in the Journal of Caffeine Research, aims to demonstrate how difficult it is to achieve a reduction in coffee consumption, so deeply rooted worldwide is the consumption of this beverage, to the point of today representing a serious phenomenon of "addiction risk", even if still little studied.
here is the Johns Hopkins School of Medicine study, dated 2003, on caffeine addiction