London, July 20: Drinking coffee can cause tip-of-the-tongue moments when the brain struggles to retrieve information.

Caffeine, widely held to make people more alert, can make the mind go blank or struggle to switch between trains of thought, researchers claim in a study in Behavioral Neuroscience.

Volunteers were split into two groups, with one given 200 milligrams of caffeine — equivalent of two cups of coffee. They then answered 100 questions after reading 10 “priming words” with between two and eight of the words sounding similar to the answer. Caffeine appeared to help participants find answers when primed with similar sounding words. But when there were more unrelated priming words they suffered more tip-of-the-tongue moments.