Caffeine consolidates memory

People have long used caffeine to help them stay awake and study for exams, but new research says it may be doing more than just keeping you alert. According to a paper published in Nature Neuroscience this week, caffeine can actually improve memory formation.

Johns Hopkins University researcher Daniel Borota and his colleagues asked a group of volunteers to categorise pictures into things you use inside or outside the house, and then gave them either caffeine, or a placebo.

A day later, the subjects were brought back, shown another set of pictures, and asked to identify whether each was one they'd been shown before, a new image, or one very similar to a picture they had seen the day before.

Both the caffeine and placebo groups were equally good at categorising the old and new pictures, but participants dosed with caffeine the day before were significantly better at recognising pictures that were similar.

This suggests that the caffeine, given immediately after they had first seen the pictures, had helped them form clearer memories, a process known as consolidation. Giving caffeine a day after seeing the pictures, on the other hand, had no effect.

The researchers also tried different doses of caffeine. One hundred milligrams (mg), which is roughly equivalent to 1 shot of coffee-shop espresso, had no measurable effect. But 200 and 300mg doses, correponding to two to three cups of coffee, produced the improvement in recall.

The team aren't certain why caffeine helps memory consolidation, although it seems to have this effect in other animals as well as in humans.

Caffeine blocks adenosine, which is linked to feelings of fatigue and weariness. This might improve alertness and therefore boost the attentiveness of the subjects towards the picture task, thereby improving consolidation.

Alternatively, caffeine could be acting directly to boost activity in the brain's hippocampus, which is a key site for memory formation.

Further work is needed to find out the mechanism, but it certainly seems that a cup of coffee when you are revising could help recall you later rely on...