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
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.
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?
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 gr...
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.
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.
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.
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 sudde...
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...?
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.
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.
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.
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 ...
In the study which found impaired neurogenesis the rats were consuming caffeine chronically. Were the impairments in neurogenesis due to sleep deprivation which would not occur in morning-only human coffee drinkers?
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.
I don't trust a single one of these findings, as I don't trust their proxies to be of any real use, I don't trust their methodology to be representative of the real world, and frankly I'm extremely skeptical that any result I see is not classical statistics shenanigans before I at least see it confirmed by a meta-analysis based on large number of trials.
Do you also distrust neurochemistry? Caffeine has a known mechanism of action. It's not poorly understood like modafinil. Caffeine binds to certain types of adenosine receptors, but it doesn't activate them. This prevents adenosine from binding to and activating the receptors. Adenosine does a lot of things, but one thing it causes is sleepiness. If you increase the amount of adenosine in someone's brain, they get sleepy. The amount of adenosine in the brain naturally increases over the day until you fall asleep. So if adenosine makes you slow and sleepy, blocking it should make you sharper and more alert. It's no surprise that most people report caffeine having that effect on them.
So, there are a bunch of studies. There's a known mechanism of action. There are lots of caffeine users who can confirm the effects predicted by the studies and the neurochemistry. You can even get firsthand evidence if you try the drug yourself. What more do you want?
Anyone have any experience or advice about optimal dosing? What is the maximum amount of caffeine I can consume while still avoiding dependency? What pattern of consumption is best?
Personally I find caffeine to be amazing for basically everything, but it becomes too weak after you build some tolerance, and withdrawal seems to affect me particularly badly.
In vitro, caffeine actually encourages hippocampal dendrite growth http://news.bbc.co.uk/2/hi/science/nature/472473.stm - unless this finding (from 1999?) was wrong. That said, the studies claiming that caffeine impairs some types of learning and hippocampal neurogenesis in live rats is probably more applicable in predicting the effects of human consumption.
To reason about Caffeine consumption, or the consumption of any mental enhancer, one should not consider only the damages and benefits of it. But the difference between those and the ones you'd have from consuming other enhancer.
Compare it with other stuff, not just being sober, otherwise, you are falling into the fallacy of the bicameral mind. The mind that evolved to think that everything is 0 or 1.