Caffeine is a drug found in coffee, tea, and cocoa. It is regularly consumed by millions of Americans on a daily basis. Most are aware of its function as a pick-me-up; however, a new study has found that caffeine consumption can boost long-term memory function. The findings were published online on January 12 in the journal Nature Neuroscience by researches in the Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland.
The study authors noted that it is currently unknown whether caffeine can augment long-term memory in humans. Therefore, they conducted a post-study caffeine administration to test its effect on memory function. The study group comprised 160 individuals between the ages of 18 and 30. The study involved two phases. In the first phase, the subjects looked at pictures of various objects and were asked to determine whether they were “indoor” or “outdoor” products. After they provided the information, the participants received either a 200 mg caffeine pill or a placebo pill. The following day, the subjects were shown another series of photos; some were new and some were the ones that they had viewed the day before. The participants were then asked to categorize them as “new,” “old,” or “similar to the original pictures.”
The researchers found that, compared to the individuals who had received a placebo pill, those who received the caffeine pill on the previous day were better able to identify which pictures were similar to the ones they had seen the day before. Both groups accurately identified which images were new, and which were old.
Further tests found that the subjects performed better after a 200 mg dose of caffeine, compared to a 100 mg dose. However, when they ingested a 300 mg dose of caffeine, there was no difference in memory compared to when they took a 200 mg dose. Furthermore, the subjects who took a caffeine pill before the memory test, as opposed to after, showed no memory improvement.
The researchers plan further testing on the effect of caffeine on long-term memory; their goal is to determine what causes caffeine to improve long-term memory.
The following caffeine levels have been reported for coffee
- Brewed (8 ounces): 95-200 mg
- Brewed, decaf (8 ounces): 2-12 mg
- Espresso (1 ounce): 40-75 mg
- Espresso, decaf (1 ounce): 0-15 mg
- Instant (8 ounces): 27-173 mg
- Instant, decaf (8 ounces): 2-12 mg
Take home message:
Caffeine acts as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness. However, caffeine overdose can produce overstimulation of the central nervous system. It usually occurs only after consumption of large amounts of caffeine, well over the amounts found in typical caffeinated beverages and caffeine tablets (e.g., more than 400–500 mg at a time). This study reported that caffeine can improve long-term memory; however, it also found that 300 mg did not have any additional benefit over long-term memory; thus, moderation is the key.