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I think it's worth noting that caffeine is a vasoconstrictor, at least with respect to blood vessels in the brain. (Aside: This may be why it provides partial headache relief for some.)

So while it's true that our brains get a stimulating boost from caffeine, it's also a fact that caffeine significantly reduces cerebral blood flow. A moderate dose (250 mg) may reduce cerebral blood flow by 27%(!)

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2748160/

I'm no brain scientist but I would expect this to reduce some cognitive function to some degree.

2 comments

Anecdotally, with caffeine I find it easier to do something concrete and relatively mindless, such as cleaning, or writing code that’s similar to something I’ve written before; but it’s much harder to figure out something novel or explain things to others. I wouldn’t be surprised if reduced blood flow turned out to be one cause of that effect.

If you dig you can find research that indicates that caffeine is the most potent cognitive boosting chemical we know of to date.

I think the first half of your point, that we're reducing blood flow to the brain, is a valid one. However, evidence indicates that whatever negative impact on cognition occurs are overpowered by the positive impacts.

Another factor to consider is how much blood flow is correlated to cognitive abilities. Obviously some is needed, but after sufficient oxygen levels are reached I suspect other factors (such as glial cells) play stronger roles.

Definitely a fascinating field of study.

More potent than adderall?

Yes, they included amphetamines in their study.