Brain training does not do what it is sold as doing
The pitch is always roughly the same. Play these games for ten minutes a day and your memory, focus and processing speed will improve. There is a graph. There is often a university mentioned.
The finding underneath is real and much narrower than the pitch: you get better at the game.
Near transfer, far transfer, and the gap between them
Researchers separate two questions. Does training on a task improve that task? Yes, always, and quickly. Does it improve tasks you did not train? That is transfer, and it is where the argument is.
Near transfer means improvement on a very similar task. It shows up sometimes, modestly. Far transfer means improvement on the things you actually care about: following a conversation, holding a plan in your head, being sharper at work. That is what the advertising implies, and it is the one the evidence has been least kind to.
The most cited studies with strong positive results tend to be small, to compare against a control group that did nothing at all, and to be run by people with a commercial interest. Larger studies with active control groups, where the comparison group also does something engaging, generally find much less.
Improving at a memory game is not evidence about your memory. It is evidence about the game.
This is not a fringe view
In 2016 a large group of cognitive psychologists and neuroscientists published an open letter saying the collective evidence did not support the claim that brain games improve general cognitive ability or everyday functioning. The same year, a major brain training company settled charges with the US Federal Trade Commission over advertising that regulators said was not supported by the science.
The industry did not disappear, and the claims have generally got vaguer rather than better supported.
Why the correlation is so persuasive
People who do lots of puzzles do tend to score better on cognitive tests. That is a real observation and it is the backbone of a great deal of marketing. It is also close to useless as evidence, because the causation is at least as likely to run the other way: people who find that sort of thing rewarding are disproportionately people who were already good at it.
The way to separate the two is to assign people at random and see what happens. Those studies exist, and they consistently find smaller effects than the observational ones. Whenever a result shrinks as the design gets stronger, that is a signal about the result, not about the design.
How to read the headline version
The same pattern turns up across the whole brain-health genre, and two habits will get you most of the way through it.
Ask whether the percentage is relative or absolute. A 40% reduction usually means relative. Moving something from 1 in 100 to 0.6 in 100 is a 40% relative fall and a 0.4 point absolute one. Both are true; only one is quotable.
Ask what the comparison group did. If they did nothing, some of the effect is simply the attention, novelty and effort of doing something. That is why an active control matters, and why studies without one tend to report the larger numbers.
What we do with this
Our tests are entertainment and we say so on every result page. Taking them repeatedly will make you better at them, and that is the same near transfer described above: worth having if you enjoy it, and not a claim about you.
The one exception is worth naming. Mental rotation genuinely does improve with practice, more reliably than almost anything else we cover, and even there how far it carries beyond the task is a live argument.
None of this is health advice, and we are not the people to ask for any. If something about your memory or concentration is worrying you, that is a conversation with a qualified professional rather than with a quiz.
Brain training questions people actually ask
What is the best way to train your brain?
Learning something genuinely new and difficult, over a long period, has better evidence than any commercial training app. Education is the single intervention with the strongest track record for raising measured cognitive scores. Sleep and aerobic exercise both have decent supporting evidence. Puzzle apps have the weakest.
Does brain training work?
It works on the trained task, reliably and often dramatically. Whether it transfers to untrained tasks is contested and the strongest reviews are not encouraging: near transfer to very similar tasks sometimes appears, far transfer to everyday thinking mostly does not. In 2016 a large group of scientists published an open letter disputing the industry's claims, and a major provider settled advertising charges with the US Federal Trade Commission that year.
Is there a supplement that actually helps the brain?
We do not give health advice and this is a question for a doctor or pharmacist, not a quiz site. What we will say is how to read the marketing: a supplement claim resting on one small study, on an animal model, or on a correlation in observational data is not the same as evidence that taking it will do anything for you.
What does a 40% reduction in a headline actually mean?
Usually a relative change, not an absolute one, and the two look nothing alike. If something moves a risk from 1 in 100 to 0.6 in 100, that is a 40% relative reduction and a 0.4 percentage point absolute one. Headlines quote the first because it is the larger number.
Do puzzle games keep your mind sharp as you age?
They keep you sharp at those puzzles. People who do a lot of puzzles do tend to score better, but that is largely a correlation: people who were already sharper are more likely to take up puzzles, and studies that randomly assign people to puzzling find much smaller effects than studies that simply observe who does it.
What actually raises measured scores?
Schooling has the best evidence, with estimates commonly between one and five points per additional year. Beyond that, the honest answer is that most of the interventions with big marketing budgets have small or contested effects, and the ones with decent evidence are unglamorous.