Originally Posted by Psychology Today: Your brain on creatine
So let's look at these papers, shall we? In both the cognition study papers, healthy college students were recruited (colleges being both a good source of research volunteers and vegetarians) and divided into creatine or placebo supplementation groups. The British study compared vegetarians and vegan young women to omnivores, the Australian study used only vegetarians and vegans, but had a crossover design (all subjects got both placebo and creatine along the way). Both studies did various measures of cognitive and memory testing (number of words you can remember from a list read to you, how many F or P words you can say in two minutes, how many numbers you can repeat backwards from a string of numbers read to you, recognizing strings of three even or odd numbers in a series of numbers read at 100 per second). The British study added a measure of reaction time (subjects had to press a button corresponding to a light as fast as they could once it was lit). The Australian study was six weeks, the British study was five days, and both used 5g creatine monohydrate as the supplement and dextrose (glucose) as the control.
Because glucose administration has been shown to (immediately) increase cognitive performance (5 (link is external)), all the cognitive testing was done fasted and on a day with no supplementation.
The results? First off, everyone, vegetarian or omnivore, on placebo or creatine in the British study did worse the second time around on the memory tests (maybe they got bored?). But compared to the placebo group, the omnivores in the British study were about the same as the creatine supplement group (omnivores have been shown to benefit from a maximum of 20 grams a day at first then maintenance 2-5 grams per day supplementing for athletic performance), suggesting that us animal flesh eaters have a physiologically appropriate amount of phophocreatine reserve in the brain for interesting tasks such as pushing buttons in response to light stimuli and complicated mental tasks that involve the prefrontal cortex and the hippocampus.
The vegetarians in the creatine group did much better than the vegetarians in the placebo group on the second battery of tests involving word recall and measures of variability of reaction times. More simple mental tasks didn't improve in the vegetarians or the omnivores, suggesting, interestingly enough, that complicated thinking burns more energy than uncomplicated thinking (so do smart people burn more calories? I'm not aware of any research to that effect, in fact I thought there wasn't much of a difference, but we'll look into it ...). In some of the measures, vegetarians were higher than omnivores at baseline, by the way, and in general the memory tests between the two groups did not vary at baseline—the vegetarians just seemed to benefit much more from creatine supplementation.
In the Australian study (using only vegans and vegetarians), creatine supplementation had a significant positive effect on working memory (using backwards digit span) and intelligence measures requiring processing speed. Various cognitive tasks that were worse in the placebo vegetarians compared to creatine vegetarians are similar to those that are affected in ADHD, schizophrenia, dementia, and traumatic brain injury. In addition, people with the Apoe4 allele and therefore more vulnerable to developing Alzheimer's seem to have lower brain levels of creatine.