Sunday, July 1, 2012

"Caffeine: A User’s Guide to Getting Optimally Wired"

From Developing Intelligence:
Caffeine is the most widely used stimulant in the world, but few use it to maximal advantage. Get optimally wired with these tips.

1) Consume in small, frequent amounts.
Between 20-200mg per hour may be an optimal dose for cognitive function.
Caffeine crosses the blood-brain barrier quickly (owing to its lipid solubility) although it can take up to 45 minutes for full ingestion through the gastro-intestinal tract. Under normal conditions, this remains stable for around 1 hour before gradually clearing in the following 3-4 hours (depending on a variety of factors).
A landmark 2004 study showed that small hourly doses of caffeine (.3mg per kg of body weight [approx 20 mg per hour; thanks digg!]) can support extended wakefulness, potentially by counteracting the homeostatic sleep pressure, which builds slowly across the day and acts preferentially on the prefrontal cortex (an area of the brain thought responsible for executive and “higher” cognitive functions).
At doses of 600mg, caffeine’s effects on cognitive performance are often comparable to those of modafinil, a best-of-class nootropic.

2) Play to your cognitive strengths while wired.
Caffeine may increase the speed with which you work, may decrease attentional lapses, and may even benefit recall – but is less likely to benefit more complex cognitive functions, and may even hurt others. Plan accordingly (and preferably prior to consuming caffeine!)
Caffeine has long been known to improve vigilance, but work focusing on its more more cognitive effects – through interactions with the “frontal task network” – show less clear effects.
In tests of lateral prefrontal function, caffeine only remediates some fatigue-related symptoms. For example, in a random number generation task (a commonly-used measure of prefrontal function), caffeine increased the quantity of numbers generated to pre-fatigue levels, but did not significantly affect more demanding aspects of performance: caffeine didn’t affect the likelihood of subjects generating numbers outside the acceptable range, or their tendency to perseverate on particular numbers.

Another study indicates the same is true of caffeine’s effect on the medial prefrontal cortex. In that study, sleep deprivation-related decrements on the Iowa Gambling Task were not mitigated by caffeine.
The Stroop task, which a wealth of neuroimaging shows is related to functioning of the anterior cingulate, may also benefit from caffeine, but this effect may also be due to general speed improvements rather than those of cognitive control specifically.

(Interestingly, it appears that none of these studies follow guideline #1 – and there are hints in the second one that subject’s performance might have shown significant improvements if another dose of caffeine had been provided about half-way through the task).
Recall from memory may be improved by caffeine (here and here), possibly due to enhancements in memory encoding rather than retrieval per se. Another study shows caffeine can actually impair estimates of “memory scanning” speed (in the Sternberg paradigm), so the failure of many studies to find recall-related effects of caffeine may reflect a speed-accuracy tradeoff at the time of retrieval.

3) Play to caffeine’s strengths.
Caffeine’s effects can be maximized or minimized depending on what else is in your system at the time. ...MORE
We first linked to this in 2008 with a HT to Freakonomics but this time the HT for the reminder goes to Barking up the Wrong Tree.
Also at Barking:
What's the secret to amazing naps?

The more in-depth "What Caffeine Actually Does to Your Brain.