Caffeine is good for your brain
physorg.com
physorg.com
You can find the whole issue online here: http://iospress.metapress.com/content/t13614762731/
This special issue arose from a meeting held in Lisbon, in July 2009, on "Caffeine and the Brain".
The meeting, and this special issue of the journal, were sponsored by the Associado Industrial e Comercial do Cafe: the Industrial and Commercial Coffee Association.
It is claimed that this organization "generously financed both the meeting and this special issue while leaving full scientific independence to all contributors". Even if that's perfectly true, I suggest that there might be just a teeny bit of selection bias in the papers in this issue of the journal.
[EDITED to add: of course there is no mention of the sponsorship in the PhysOrg article. Why is it that every single time I see a PhysOrg link on HN there's something rather wrong with it?]
It's important to be aware of where the money is coming from. That said, the journal is peer reviewed, and this sort of sponsorship is not uncommon for either journals or conferences. One would dismiss a wide swath of research if one concentrated more on funding sources than quality of data. (Not that you were doing that, just sayin'.)
Caffeine has always caused me to have a heightened level of anxiety that lasts much longer than initial high. My recommendation is that you should sleep when you are tired. I like to take a nap in my car during lunch.
For me, coffee is drastically inferior to the high I get from earl grey tea (most black teas in general). I find that with tea the high is much smoother and lasts longer; if you can imagine a bell curve, it would be wider and with a smaller amplitude, whereas coffee would be narrower and with a taller amplitude.
Also, I've found a 20 minute nap at mid-day with green tea afterwards (about half the caffeine content of my morning breakfast tea) to be much more effective in improving cognitive performance than to skip the nap and rely solely on caffeine. For the rest of the day I'm caffeine free.
</personal-experience-disclaimer>
Unrelated, but: http://theoatmeal.com/comics/caffeine
In the case of caffeine I suspect the main benefit is that drinkers of tea and coffee eat less food, and rich food damages the blood vessels of the brain (as it does to the heart).
In that sense it is similar to nicotine, and NON-smokers are 50% more likely to develop alzheimer's (controlling for increased mortality).
One current alzheimer's medication is Galantamine ( http://en.wikipedia.org/wiki/Galantamine ), which also increases acetylcholine levels and nicotinic acetylcholine receptor activity specifically.
The problem with these questions is that their answers aren't absolute. It varies significantly depending on the person, their genetic makeup, and their lifestyle. Even doing seemingly healthy things can be bad depending on your makeup.. enough 20-30 year olds have died during moderate exercise to show us that.
There are enough old smokers, heavy drinkers, drug takers, and what not, to demonstrate that these activities are not guaranteed to kill you. Studies merely attempt to show, statistically, the damage that "can" be caused or is "more likely" to be caused than by not consuming the item.
Given that we're haven't worked out how to determine what substances are or aren't helpful to us on an individual basis, I consume whatever I like as long as it doesn't make me feel bad. I might die tomorrow, I might die when I'm 90, que sera sera.
Same argument and every bit as delusional.