They’re sold as the cranial equivalent of health food, exercise and fresh air: brain games.

And their message: Why waste precious moments crushing candy and flinging digital birds when you can bulk up your brain and have fun at the same time?

What’s not to love, right?

Developers have for years offered dozens of games said to boost mental fitness, from the high IQ society Mensa’s own offering on the Apple operating system to Big Brain Academy on the Nintendo Wii and the venerable Brain Age, a suite of games that began selling in 2005 for the Nintendo DS.

But the biggest brain game on the market today is Lumosity, which is actually a suite of services with versions for the web and smartphones. And like other brain game makers, Lumosity’s marketing material claims that playing the games will make you smarter. As opposed to popular entertainment games like Candy Crush and Angry Birds, brain game makers say the challenges their games provide treat your brain like muscle, straining it to build better neural connections.

But some brain scientists and game designers are not convinced.

“If you enjoy them, you should play them,” said Pamela M. Kato, Ph.D., owner of P.M. Kato Consulting and visiting professor of Serious Games for Coventry University. “The only question I have is the impact they have on real life.”

The folks behind Lumosity and other brain trainers say the impact is huge. According to Lumosity‘s marketing materials, the company’s games improve several areas of cognition — memory, problem solving, speed, attention and general flexibility.

They do it by presenting — online and offline — computer games and puzzles. Each test is scored, ranked and saved. You can play it again later, and watch your score improve.

For example, one series of games utilizes a quirk called the Stroop Effect, which demonstrates the difficulty the brain has when it encounters conflicting bits of information.

To take the test, you get a series of names of colors, first written in a colored font that matches their name (the word “red” in red ink, for example) and then a second list with color names in a differently colored font (the word “red” in green ink).

The tests time how long it takes a person to name the correct colors of the words on the first list, then how long it takes you to do the same with the second list. The difference is your score.

Another task popular among games is sorting numbers. That’s one of the free web games that Cambridge University’s Brain Sciences project offers ( The player is confronted with a palette of numbered tiles and has to sort them into numerical order in the fewest moves and shortest amount of time. It’s designed to test a player’s ability to plan, thinking several steps ahead.

“Playing games like that (the color-naming game), you do get better at identifying names versus colors,” Kato said. “You certainly get faster, but I don’t think it’s been shown that those results translate to better thinking.”

A 2010 paper published in the November 2010 Journal of Neuroscience called the theory behind the brain trainers into question. Neuroplasticity — the idea that you can rewrite the brain’s neural connections — occurs in children regularly, but it’s harder to make happen in adults. Adults may learn how to play a game, but it’s a matter of behavior, not physically pumping up the brain’s gray matter, according to the paper.

Kato compared it to taking sample tests from Mensa, the high IQ club.

“If you take enough of those tests and then take an IQ test, you will get a higher score,” she said. “You may have a higher IQ, but are you really smarter?”

Kato says games can have a positive effect — but it’s often indirect and changes behavior rather than brain structure.

Kato is behind Re-Mission, a series of games aimed at young cancer patients. It’s designed to show them a simplified, cartoonized version of what’s going on in their bodies as they take chemotherapy treatments and radiation therapy to fight their cancer.

It doesn’t fight cancer directly, but helps kids come to terms with what’s going on and why doing something as miserable as chemotherapy can be important.

Kato’s results have shown that kids that play Re-Mission are more likely to be faithful about holding true to their therapy.

“And their therapy is the thing that can help them beat the cancer,” she said.

Games can prompt good changes, but by changing behavior, not physical structure of the brain, she said.

The BBC and Cambridge University reached much the same conclusion in 2010. They challenged 13,000 people across Great Britain to try the brain trainers, testing them at the beginning of the project and again six months later.

The people who used the games regularly didn’t do any better on the second test than people in a control group who simply surfed the Internet for 20 minutes a day.

“Research shows that people that play brain games regularly do better at playing those games, but do they really help? I don’t know,” Kato said. “They may help keep your mind active, and that’s a benefit, but any activity that keeps your brain active could have the same effect.”

There are alternatives. Both the Android Play store and Apples iOS iTunes store have categories of puzzle games, both for sale and for free. Number and letter sorting games like sliding number puzzles (here on the iOS ; here on Android ) and Wordament (here on the iOS and here on Android ) are available. And there are Sudoku games and crossword puzzles available on a computer, a smartphone or in a good old-fashioned paper.

But Kato said there are things out there that can build brain power, as opposed to keeping it active.

“If you really want to improve your brain, play a game that helps you learn something,” she said.

Apps like Duolingo and Babbel help you learn another language — everything from Spanish to Indonesian to Dutch.

Games like Lightbot and Hard Coder can help you learn the basic theories behind writing computer code. And there’s the Instructables app, which explains how to make random — and sometimes useful — crafts and projects.

And if all you are looking for is something to do with your hands while you’re waiting in line, go ahead and play a brain game.

“It won’t hurt you,” Kato said. “If you enjoy them, there’s no reason not to.”

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Ways to improve your brain power

— Focus: In his 2008 book “Brain Rules,” molecular biologist John Medina declared multi-tasking a myth. Attentional consciousness does jobs serially, one at a time. Switching from one task to another — checking your Twitter feed and texting a friend while trying to balance the checkbook — forces different and competing brain processes to start up and stop. It’s less efficient and not the best way to operate your brain.

— Take a break: Medina admits that texting, Twitter, music and games have their place, however. Adult human brains can concentrate on a single task for about 600 seconds before wandering, according to Medina’s sources. He recommends 10 minutes of work on one subject, then taking a break, then getting back to it.

— Novelty: Trying something different — ordering different items on the menu, driving a different way home from work, trying new clothing styles — creates the opportunity for new perspectives, and that can help build new neural pathways.

— Exercise helps: A November 2010 Journal of Neuroscience article found that aerobic exercise helped elders focus better, perform tests better and are less easily distracted. Exercise is one of “Brain Rules” author Medina’s top tips.

— Get enough sleep: Medina said it’s measurably true that people lose mental acuity when they don’t get enough sleep, even though an adult human brain remains active during sleep. Whether you need 10 hours each night or feel rested after six hours, make sure you get it. Medina is even a proponent of mid-day naps.

— Watch your diet: Blueberries may help improve the short-term memory, according to a Tufts University study. The lycopene in tomatoes has been shown to help, too. Fresh fish and nuts have been shown to have a positive benefit. What hurts? Too much sugar — processed or otherwise — has been shown to hurt the brain in the long term.

Learn a new language: Bilingual brains keep both languages loaded, whether the languages are being used or not, according to studies by McGill University and Toronto’s York University. That may actually force your brain to re-map and re-write neural pathways.

— Laugh: A good joke involves three different sections of the brain, promoting some sort of interconnectedness, according to the Salk Institute. Studies have shown it also acts as a stress reducer.

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