I like my women the way I like my coffee: detrimental to hippocampal neurogenesis, but conducive to short term memory and attentional control.

Memory formation and memory retrieval are very different tasks, so one should be specific when making claims like "Caffeine helps long term memory." For example, if caffeine only hinders long term memory formation, but not retrieval, then this would suggest using it during an exam, but not while studying. If vice versa, then vice versa.

Unfortunately for our purposes, the authors of your first article have blurred this distinction in their abstract, no doubt because it was not the subject of their study: their method was to add caffeine to rats' water supplies, without controlling the timing of the doses in relation to the events of formation and retrieval.

I was happy to find your last article addresses precisely this question:

Groups of 12 adult male Wistar rats receiving caffeine (0.3-30 mg/kg, ip, in 0.1 ml/100 g body weight) administered 30 min before training, immediately after training, or 30 min before the test session were tested ... Post-training administration of caffeine improved memory retention at the doses of 0.3-10 mg/kg ... but not at the dose of 30 mg/kg. Pre-test caffeine administration also caused a small increase in memory retrieval .... In contrast, pre-training caffeine administration did not alter the performance of the animals either in the training or in the test session. These data provide evidence that caffeine improves memory retention but not memory acquisition, explaining some discrepancies among reports in the literature.

Nice article, IMO. Its conclusion might suggest drinking caffeine right after study sessions (or in breaks between them, while ruminating on the ideas) is the best strategy. On the other hand, perhaps in the long term, the non-specific effects of the first study would dominate.

Personally, I'm definitely unconvinced by these data as to how I should be using caffeine, but as you can see you've got me very curious!

What do you think?

I'm happy to free-ride off of your opinion. Relative to the other things I'm working on, deciding whether to drink coffee or not seems like a fairly minor optimization. And doing my own research when I've already got this (seemingly solid) analysis of yours is an even smaller optimization.

It's not clear to me exactly what types of learning or memory cause the hippocampus to grow, even after reading this article. I don't even think they have a clue whether there's a training effect such that the added neurons make it generally easier to process new inputs for learning/memory - that is, they're seeing a correlation and speculating that there's causation in both directions.

However, I'm reminded that severe stress (see Sapolsky's "Zebras") causes the hippocampus to shrink (and the amygdala, which is apparently involved in fear, to grow). I drink a single shot of espresso daily, and I do feel alert/stressed at times (when the matter I'm thinking on doesn't seem to merit such a reaction). I wonder if the feeling of stress is a reliable signal that the hippo-neurogen. is suffering.

In any case, I feel my failures to learn and remember as rapidly as I'd like are mostly caused by age and insufficient sleep. But since I've never found caffeine difficult to give up (in the doses I've used), I'll definitely consider selectively cutting back (when I'm trying to free-associate, or learn a bunch of less-routine things).

It's also possible that some of these effects are very difficult to demonstrate at moderate doses, or in humans as opposed to rats. It would be helpful to me if you could give your estimate of dose-effect from your reading of the science.

Re: "Use caffeine for short-term performance on a focused task (such as an exam)."

Really? What about state-specific memory? If you are intoxicated by caffeine during an exam, don't you need to be taking it during the revision process as well?

Caffeine, of course, is rather addictive.

So one might (and I do) find it difficult to optimize finely according to what tasks one is attempting. The addictive nature of the drug probably explains the "always or never" consumption pattern.

What do you think?

Your summary roughly matches my own research and is confirmed, for what it is worth, by my own anecdotal experience.

I'll note that similar (but stronger) effects can be expected from the more direct stimulants (amphatamine, methamphetamine, etc.).

ETA: Regarding attention control, be aware that sometimes increased 'attention control' comes in the form of increased focus on the immediate task which can actually reduce the ability to switch tasks smoothly. This can affect the balance of attention you place on social details relative to task details when the situation at hand requires both.

I cycle caffeine and ephedrine to avoid the withdrawal and dependence effects. Of course, I always combine Ephedrine and caffeine on important test days. There seems to be a multiplier effect. The improved focus is especially important on long tests, which generally become a battle of attrition.

I also used the EC stack as a weight-loss tool with great success. It powerfully wards off hunger, and I simply forget to eat meals when I'm using EC.

I like your meta-analysis on to which kinds of tasks coffee works better.

I add something on the how much. Frequent small doses gives you better results than few large doses.

Actually, whenever in the absence of further specific evidences, I have found that small-doses-many-times is a good rule of thumb for a vast array of substances (eg: food in general, sugar) if the goal is to maintain a stable, productive mental state.

There are conflicting issues though. There are studies (that I read years ago, and have no link to) that show that consistency is better... that consistent low-level caffeine drinkers are more alert than their non-caffeine colleagues, but less jittery than high-caffeine people (optimum seemed to be 2-3 cups per day).
Associated with that would be method of consumption: concentrated does (espresso) v. sipping american coffee over an afternoon. Using is in a "targeted" manner might fail you: If you are not particularly used to the effects and suddenly drink coffee for short term memory reasons, you might not get the desired result because you'd be too "hepped-up" (to use the technical term...ha!).
If you ARE used to drinking coffee, and suddenly avoid it for long term learning reasons, you might be either sleepy or hit withdrawal.

I have sort of been doing what you recommend anyway, because I found needing coffee to be normally awake (like my father does) absolutely unacceptable. I like coffee, but I never drink it unless there is a specific reason to. The same for tea, and I almost never drink coke anyway because I prefer the taste of most other non-alcoholic beverages, including cold tape-water.

But I never noticed any effect on me, so recently I haven't bothered drinking coffee for anything but social reasons ( a cup every two weeks or so). Maybe I'll try it again next time. Or maybe I need a higher dosage? When I was drinking coffee for effect it was 1 or 2 cups, I thought that should be enough because I normally don't drink any but maybe I should have tried more.

Here's a recent Lifehacker article covering some of the same ground as well as some other stuff, including withdrawal: What Caffeine Actually Does to Your Brain

Although the evidence is far from conclusive, regular caffeine consumption may have neuroprotective effects, perhaps more likely among women and older people.

1. Ritchie K, Carrière I, de Mendonca A, Portet F, Dartigues JF, Rouaud O, Barberger-Gateau P, Ancelin ML. The neuroprotective effects of caffeine: a prospective population study (the Three City Study). Neurology. 2007 Aug 7;69(6):536-45.

2. Rosso A, Mossey J, Lippa CF. Caffeine: neuroprotective functions in cognition and Alzheimer's disease. Am J Alzheimers Dis Other Demen. 2008 Oct-Nov;23(5):417-22.

3. Corley J, Jia X, Kyle JA, Gow AJ, Brett CE, Starr JM, McNeill G, Deary IJ. Caffeine consumption and cognitive function at age 70: the Lothian Birth Cohort 1936 study. Psychosom Med. 2010 Feb;72(2):206-14. Epub 2009 Dec 7.

Is there a good source of documentation for the expected side-effects of coffee - the "down" period of reduced mental capacity that often occurs a few hours after drinking, the effect of disrupted sleep cycles for those who do not normally drink the stuff, etc...?