In the 2000s, many children in Japan heard that video games could break their brains. But scientists did not find good proof for this idea.

In fact, some studies found the opposite. People who played action games were better at finding things quickly on a screen. In another study, adults played a game every day for two months, and some parts of their brains grew. But playing too much is still a problem.

In the early 2000s, the term "game brain" spread across Japan. It was the idea that video games could make young people's brains work like those of people with dementia.

Many scientists questioned how the brain waves were measured and read, and the claim never went through rigorous peer review. Studies abroad found something different. In 2003, two American researchers reported that action game players had better visual attention. Non-players also improved after ten days of play.

In a 2014 German study, adults who played a 3D game for about 30 minutes a day for two months gained gray matter in areas linked to memory and planning. Games are not always good, though. The WHO now recognizes "gaming disorder," when people lose control over gaming and their daily lives suffer.

In the early 2000s, Japanese parents kept hearing a frightening phrase in the media. "Game brain" was the claim that video games could push children's brains into a state resembling dementia. It rested on brain-wave recordings, but researchers criticized both the measurements and the way they were read, and the idea never went through rigorous peer review. Laboratories abroad were finding the opposite.

In a 2003 paper in Nature, Green and Bavelier reported that action game players beat non-players on tests of visual selective attention, and that ten days of training raised non-players' scores. A 2018 meta-analysis broadly confirmed the link between action games and better attention and perception. In 2014, Kühn and colleagues found more gray matter, including in the hippocampus, after two months of daily play. These studies have weak points of their own.

Gamers are self-selected, since people who choose to play a lot may differ from those who do not. Effects tend to shrink once publication bias is taken into account. And nobody knows how far a better score on a lab test carries over into everyday life. The WHO defines gaming disorder by loss of control over play and serious disruption to daily life.