The researchers' tests involved 72 men and women who were given water, water and caffeine, water and glucose or water and caffeine and glucose to drink first thing in the morning after fasting overnight.
They then tested various aspects of the volunteers' cognitive performance, including attention, memory and also manual dexterity - for instance, they had to remember a list of words, repeat a series of numbers forwards and backwards and sort cards according to the shapes, colours or numbers that were printed on them.
The results, published in the journal Human Psychopharmacology: Clinical and Experimental, showed the volunteers who had drunk water with either the caffeine or glucose had faster reaction times than those who'd had just water. But those who'd had the water with both caffeine and glucose performed the best.
Well, it makes a change from experts saying everything we like is bad for us. There again, it's not the first time scientists have claimed caffeine may be good for your brain. And it probably won't be the last.
How do you get your brain started in the morning?