Caffeine has been relentlessly studied for evidence of ill effect and, as you know, science publishing is biased toward positive results (so expect to see one p

Caffeine has been relentlessly studied for evidence of ill effect and, as you know, science publishing is biased toward positive results (so expect to see one positive p=0.05 outcome for 20 studies of a non-effect). I suspect that the puritan streak in our society which suspects that anything we enjoy must have an underlying evil plays a role. In any event, the evidence of the ills of caffeine is so poor as to suggest a smattering of false positives. The studies showing positive effects should be viewed with similar skepticism, although if it does have some role in preventing Alzheimer's surely that's enough on its own.