We all know coffee is a ­stimulant and its ­stimulating ingredient is caffeine. But the boost ­people get from other caffeinated drinks doesn’t come close to a cup of coffee. What’s going on?

Researchers from the Minho ­University in Portugal wanted to find out if the wakefulness effect of coffee was down to more than caffeine. And it turns out plain caffeine only partially mimics the effects of coffee.

While caffeine boosted areas of the brain that make you feel more alert, coffee had an additional influence on brain areas that affect memory and achieving goals. “There is a common expectation that coffee increases alertness and psychomotor functioning,” study co-author Nuno Sousa explained.

“When you get to understand better the mechanisms underlying a ­biological phenomenon, you open pathways for exploring the factors that may modulate it and even the potential benefits of that mechanism.” People who drank a minimum of one cup of coffee per day were recruited to the study and asked to refrain from eating or drinking ­caffeinated drinks for at least three hours beforehand.

The participants had two MRI brain scans – one before and one 30 minutes after – either taking caffeine diluted in hot water or drinking a standardised cup of coffee. Scientists found that consuming coffee and caffeine both led to lower nerve connectivity in the brain’s default network, which is involved in introspection and self-reflection.

Researchers say this change means people are more prepared to move from resting mode to working mode. But drinking coffee had ­the additional benefits of increasing the connectivity in the brain’s more advanced nerve network controlling vision, and other parts involved in working memory, cognitive control and goal-directed behaviour. This didn’t occur with just caffeine.

In other words, researchers said if you want to feel not just alert but ready to go, caffeine alone probably won’t cut it. “Acute coffee consumption decreased the functional connectivity between brain regions of the default mode network, a network that is associated with self-referential processes when ­participants are at rest,” study co-author Maria Picó-Pérez said.

She added: “The subjects were more ready for action and alert to external stimuli after having coffee.” So the findings suggest that while caffeinated drinks share some of the effects of coffee, they don’t have all the special benefits. These may include factors such as relishing the particular smell and taste or being buoyed up by the ­psychological expectation of your favourite cup of coffee.